Reconsideration of 2009 Endangerment
Finding and Greenhouse Gets Vehicle
Standards
Response to Comments
rnA United States
Environmental Protection
Agency
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Reconsideration of 2009 Endangerment
Finding and Greenhouse Gets Vehicle
Standards
Response to Comments
This technical report does not necessarily represent final EPA decisions
or positions. It is intended to present technical analysis of issues using
data that are currently available. The purpose in the release of such
reports is to facilitate the exchange of technical information and to
inform the public of technical developments.
Office of Transportation and Air Quality
U.S. Environmental Protection Agency
NOTICE
vvEPA
United States
Environmental Protection
Agency
EPA-420-R-26-003
February 2026
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Introduction
The EPA's Proposed Rule, Reconsideration of 2009 Endangerment Finding and Greenhouse
Gas Vehicle Standards, was signed by Administrator Lee Zeldin on July 29, 2025. A pre-
publication version of the proposal was made available on the EPA's website on July 29,
2025, after Administrator Zeldin's announcement of the proposal but priorto its publication
in the Federal Register on August 1, 2025 (90 FR 36288). The proposal indicated that the
docketwould be open for public comment until September 15, 2025. This date was later
extended to September 22, 2025 (90 FR 39345, August 15, 2025). The Docket ID Number
for the rule is EPA-HQ-OAR-2025-0194.
This Response to Comments (RTC) document is a compilation of public comments
submitted to the public docket for this rule as well as the EPA's responses to those
comments. Some aspects of our responses appear in the preamble to the final action or
other documents in the docket for this rulemaking and are incorporated by reference in this
document.
This RTC document is organized by category of comment topic. The original documents
submitted by commenters, including any attachments, footnotes, tables, and figures are
included in the docket for this rulemaking accessible through the regulations.gov website.
About 572,000 written comments were submitted to the public docket for this proposal.
The vast majority of these, about 534,000 comments, were submitted in the form of 169
mass comment campaigns.1 Some of these are identical letters submitted by many
individuals, while others consist of a petition with many signatures urging the EPA to take
particular final actions on the proposal or refrain from finalizingthe proposal. Some mass
mail campaigns opposed the proposal to rescind the 2009 Endangerment Finding and the
EPA's greenhouse gas (GHG) emission standards, and other mass comment campaign
commenters urged the EPA to finalize the proposal on one or more bases discussed in the
preamble to the proposal. A list of the mass comment campaigns that were received
before the close of the comment period can be found in Appendix A to this RTC document.
The EPA held a public hearing on the proposal, and the transcript of that hearing is included
in the docket for this rule noted above. During the four-day public hearing (August 19-22,
2025), more than 600 individuals testified over more than 30 hours. If public testimony
provided information that is specific in nature and was not subsequently included in
1 Seventeen mass mailers representing about 6,500 signatures were submitted after the close of the
comment period are not included in these totals.
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written comments submitted by the testifier or the testifier's organization, that statement is
addressed in this RTC document.
Note that all comments are posted in the docket, but the EPA has not considered or
responded separately to comments received after the comment period closed at midnight
on September 22, 2025. These include nearly 250 comments from individuals,
organizations, companies, or governmental entities and several mass mailers. Many of the
late comments were within a few days of the close of the comment period and raised the
same issues as timely comments. A few of the comments were significantly late (3-7
weeks or more) and raised only a few new and novel issues.
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Table of Contents
Introduction i
Table of Contents iii
1 Legal Framework for Action 1
1.1 Statutory Authority for Rescission and Repeal 1
1.2 Retroactivity 2
1.3 Change in Position Doctrine 3
1.3.1 Acknowledgement of Change in Position 3
1.3.2 Reasons for Changing Position 8
1.3.3 Reliance Interests 15
1.3.3.1 State and Local Governments 18
1.3.3.2 Vehicle Manufacturers 24
1.3.3.3 Greenhouse Gas Compliance Credits 27
1.3.3.4 Vehicle Purchasers and American Consumers Generally 28
1.3.3.5 Electric Vehicle Supply Chain 31
2 Rescission of the Endangerment Finding 33
2.1 Primary Rationale for Rescission 33
2.1.1 Best Reading of CAA Section 202(a) 33
2.1.1.1 AirPollution 33
2.1.1.1.1 Constructing the Scope of 202(a)(1) Based on Specific Air Pollutants
Identified in CAA Section 202 and Other CAA Sections 51
2.1.1.1.2 Dictionary Definitions of "pollutant", "pollution", and "air pollution"
support EPA's best reading 67
2.1.1.1.3 Whether GHGs Fall Within the Scope of 202(a)(1) Based on the CAA's
reference to Specific Air Pollutants 70
2.1.1.1.4 Background Principles of Causation and Proximate Cause and Their
Effect on the Scope of CAA section 202(a) 74
2.1.1.1.5 The Necessity of EPA's Best Reading to Avoid Absurd Results 80
2.1.1.1.6 EPA's Longstanding Practice Prior to 2009 82
2.1.1.1.7 The Effect of Massachusetts v. EPA 84
2.1.1.1.8 The Effect of Loper Bright 94
2.1.1.2 Findings and Standards 94
2.1.1.2.1 Issuing Standards Concurrent with the Findings Necessary to Invoke
EPA's Regulatory Authority 94
2.1.1.2.2 Accountingfor Policy Factors when Making an Endangerment Finding
102
2.1.1.3 Endangerment and Cause or Contribute 106
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2.1.1.3.1 The nexus between contribution and endangerment 106
2.1.1.3.2 Cause or Contribute and Nondelegation Concerns 113
2.1.1.3.3 Threshold for Cause or Contribution 115
2.1.1.3.4 Consideration of non-section 202(a) sources in the endangerment
analysis 119
2.1.1.3.5 Consideration of six "well-mixed" GHGs together as an air pollutant
121
2.1.1.3.6 The use of existing vehicle data when conducting a cause or
contribute analysis 123
2.1.1.3.7 Consideration of vehicle classes individually when making Cause or
Contribute and Endangerment findings under section 202(a)(1) 124
2.1.1.3.8 Considering carbon leakage in the Cause or Contribute and
Endangerment Analyses 125
2.1.2 Lack of Clear Congressional Authorization 126
2.1.2.1 Applicability of the Major Questions Doctrine to the Endangerment Finding
126
2.1.2.1.1 EPA's ability to regulate GHG emissions from motor vehicles in
response to global climate change concerns presents a major question 132
2.1.2.1.2 The Endangerment Finding was an unheralded use of agency power
145
2.1.2.1.3 The Endangerment Finding was a transformative expansion in agency
power 152
2.1.2.1.4 The Endangerment Finding has vast economic and political
significance 160
2.1.2.1.5 Economic Consequences 163
2.1.2.1.6 Political Consequences 166
2.1.2.2 Applicability of MQD to 2024 Vehicle Rules 168
2.1.2.2.1 The 2024 vehicle rule was an unheralded and transformative use of
agency power 173
2.1.2.2.2 The 2024 vehicle rules were of vast economic and political
significance 183
2.1.2.3 The Major Questions Doctrine does not preclude rescindingthe
Endangerment Finding 187
2.1.2.4 The statute does not provide clear congressional authorization 188
2.1.2.4.1 Constitutional concerns and nondelegation doctrine 191
2.2 Futility of Eliminating GHG Emissions from All Motor Vehicles 197
2.2.1 Significance of the material impact of emission standards on public health or
welfare when making an Endangerment finding 197
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2.2.2 Contribution determination and de minimis emissions 204
2.2.3 Application of the futility rationale to other pollutants, sources, and global
GHG emissions 205
2.2.4 Factual support for futility of the GHG motorvehicle emission standards. 208
2.2.5 Independent basis for repealing GHG emission standards 210
2.2.6 Modeling of Global Climate Change Impacts Attributed to U.S. Motor
Vehicles 211
3 Additional Proposed Bases for Rescission of the Endangerment Finding and Repeal of
GHG Emission Standards the Agency is Not Finalizing at this Time 220
3.1 Alternative Rationale for Rescission: Climate Science 220
3.2 There is No Requisite Technology for Vehicles That Meaningfully Addresses the
Identified Dangers of the Six "Well-Mixed" GHGs 220
3.3 More Expensive New Vehicles Prevent Americans from Purchasing New Vehicles
that are More Efficient, Safer, and Emit Fewer GHGs 221
4 Repeal of the GHG Emission Standards 221
4.1 Fleetwide Averaging 221
4.2 Light- and Medium-duty Vehicle GHG Program 222
4.2.1 GHG Comments 222
4.2.2 Comments Related to Criteria Pollutant Emission Standards and Other
Provisions 225
4.3 Heavy-duty Engine and Vehicle GHG Program 225
4.3.1 Comments Related to Revising Instead of Removing Heavy-duty GHG
Standards 225
4.3.2 Comments Related to NHTSA's Heavy-duty Fuel Efficiency Program (C-16
and C-17) 228
4.3.3 Comments Related to Specific Provisions in the Heavy-duty Engine Program
under 40 CFR 1036 231
4.3.4 Comments Related to Specific Provisions in the Heavy-duty Vehicle Program
under 40 CFR 1037 237
4.3.5 Other Comments Related to the Proposed Heavy-duty Engine and Vehicle
Regulations 244
4.3.5.1 Emission-Related Warranty 244
4.3.5.2 Environment and Climate Change Canada 247
4.3.5.3 Hybrid Powertrains and Hybrid Components 247
4.3.5.4 Unrepresentative vehicle masses in GEM 247
4.3.5.5 Specialty Vehicle Hybrids 248
4.3.5.6 Gliders 249
5 Impact Analysis Comments 249
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5.1 General Modeling and Analysis 249
5.2 Fuel Prices 251
5.2.1 Gasoline and Diesel Prices 251
5.2.2 Electricity Prices 252
5.3 Consumer Valuation of Fuel Costs 253
5.4 Inflation Reduction Act Tax Incentives 256
5.5 Vehicle Technology Costs 257
5.6 OMEGA and HD TRUCS Modeling Compliance 260
5.7 ConsumerTopics 261
5.8 Social Cost of Greenhouse Gases 264
5.9 Employment and Domestic Production 267
5.10 Grid Reliability and Related Topics 269
5.11 Emissions Inventories and Health Impacts 270
5.12 Benefit-Cost Analysis Topics 272
5.13 National Security 274
6 Statutory, Executive Order, and Procedural Requirements 275
6.1 Executive Order 12866: Regulatory Planning and Review and Executive Order
14094: Modernizing Regulatory Review 275
6.2 Paperwork Reduction Act (PRA) 276
6.3 Regulatory Flexibility Act (RFA) 278
6.4 Unfunded Mandates Reform Act (UMRA) 279
6.5 Tribal-Related Comments 280
6.6 Executive Order 13045: Protection of Children from Environmental Health Risks
and Safety Risks 281
6.7 Use of Artificial Intelligence for the Final Action 283
6.8 Federalism 283
6.9 National Environmental Policy Act (NEPA) 284
6.10 Procedural Requirements 285
6.11 Environmental Justice Topics 288
7 Other Comments 289
7.1 Federal Preemption 289
7.1.1 Federal Preemption under CAA section 209 289
7.1.2 Federal Preemption of Federal Common Law Claims 297
7.2 Compliance with the Environmental Research Development Demonstration
Authorization Act (ERDDAA) 298
7.3 Compliance with the Endangered Species Act (ESA) 299
7.4 Interaction with Other CAA Provisions 303
7.5 General Arbitrary and Capricious Arguments 306
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7.6 Children's Constitutional Claims 309
7.7 International Law Considerations 311
7.8 Severability Clause 317
Appendix A: Mass Comment Campaigns 318
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1 Legal Framework for Action
1.1 Statutory Authority for Rescission and Repeal
EPA Summary of Comments
The EPA received many comments expressly or implicitly recognizing the Agency's
authority to rescind the Endangerment Finding and repeal associated GHG emission
standards pursuant to Clean Air Act (CAA) section 202(a)(1) and relevant precedent
governing changes in agency position. These commenters generally agreed that nothing in
the language of the relevant statutory provisions prohibits or conditions the EPA's authority
to reconsider, revise, rescind, or repeal actions previously taken under CAA section
202(a)(1).
Several adverse commenters contested the EPA's authority for the proposed rescission and
repeals separately from the proposed bases for those actions. Some argued that
subsequent GHG emission standards built upon the 2009 Endangerment Finding such that
rescinding the Endangerment Findingwould not support repealingthe standards. Others
argued that elements of CAA sections 202(a)(1) or 307 prevent the EPA from reconsidering
these actions except in response to extraordinary circumstances, or that the repeal was
legally or procedurally barred for other reasons. Still others acknowledged that the EPA
could reconsider these actions under CAA section 202(a)(1) but argued that the Agency
must provide a more detailed justification for doing so and/or consider reliance interests
not adequately addressed at proposal or not considered at proposal in the way
commenters believed they should be considered.
EPA Response
The EPA agrees that nothing in CAA section 202(a)(1) conditions or precludes the Agency
from reconsideringthe 2009 Endangerment Finding and associated GHG emission
standards and is finalizing this action based on that authority and the well-established
legal principle that agencies may reconsider prior actions absent statutory indications to
the contrary. See, e.g., Ivy Sports Med., LLC v. Burwell, 767 F.3d 81, 86 (D.C. Cir. 2014). The
EPA finds these comments unavailing particularly because the CAA contains no limitation
on the EPA's authority to reconsider a finding of endangerment under section 202(a). Cf.
New Jersey v. EPA, 517 F.3d 574, 582-83 (D.C. Cir. 2008) (discussing the EPA's authority
under CAA section 112(c)(9) which provides the EPA explicit authority to delist source
categories). Accordingly, the EPA disagrees with adverse commenters' arguments that the
Agency lacks authority for the rescission and repeals and disagrees that the GHG emission
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standards could stand absent the invocation of CAA section 202(a)(1) authority in the 2009
Endangerment Finding. See section IV of the final action preamble and section 1.2 of this
document for further discussion. In addition, the EPA has satisfied its obligations to
acknowledge the changes in position finalized in this action, including with respect to the
Agency's view of the best reading of CAA section 202(a)(1), the application and impact of
the major questions doctrine (MQD) to CAA section 202(a)(1) and the trend in the Agency's
GHG emission standards toward forcing a transition toward electric vehicles (EV), and the
Agency's view of the proper way to consider futility in interpreting CAA section 202(a)(1)
and evaluatingthe propriety of GHG emission standards for new motor vehicles and
engines. See section IV of the final action preamble and section 1.3.1 ofthis document for
further discussion. Finally, the EPA has satisfied its obligations to reasonably explain these
changes and consider significant and legitimate reliance interests in the Agency's prior
positions to the extent permitted by law. See section IV of the final action preamble and
sections 1.3.2 and 1.3.3 of this document for further discussion.
1.2 Retroactivity
EPA Summary of Comments
Several commenters asserted that the EPA's proposal would impermissibly enact
retroactive regulations. Specifically, these commenters argued that the EPA's proposed
repeal of GHG emission standards for modelyear (MY) 2026 and earlier vehicles and
engines operate retroactively, since those regulations have already been applied
to previously new vehicles, which are now in use. Nonetheless, these commenters
continued, the Agency indicates that the existing GHG standards - as well as supporting
compliance measures - are to be rescinded and can no longer be enforced against in-use
vehicles. On this basis, these commenters argued that the EPA lacks authority to make
such a retroactive change, citing to case law stating that a "statutory grant of legislative
rulemaking authority will not... be understood to encompass the power to promulgate
retroactive rules unless that power is conveyed by Congress in express terms." Bowen v.
Georgetown Univ. Hosp., 488 U.S. 204, 208 (1988). These commenters argued that the
statute not only fails to confer retroactive rulemaking authority, but it explicitly and
impliedly denies such authority.
Commenters argued that the best reading of CAA section 202(a)(1) is that endangerment
findings operate prospectively only unless reconsidered under CAA section 307 or in
extraordinary circumstances like mistake or fraud. In their view, the EPA is therefore
authorized to make a positive endangerment finding, or a negative endangerment finding,
with prospective application, but may not withdraw a past finding as the Agency proposed
to do here.
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In addition, commenters argued that Congress has provided a mechanism for updating
vehicle standards based on new understandings of science, technology, and economics of
motor vehicle emissions control. Under what they described as the limited statutory
mechanism in CAA section 202(a)(1) to "revise" the standards, commenters asserted that
the EPA lacks authority to retroactively rescind all prior GHG standards.
Commenters also noted that EV manufacturers have already earned credits for certain MYs
that have already been manufactured. On this theory, the EPA's action would excuse
manufacturers from longstanding compliance obligations based on a new legal
interpretation, effectively rewarding laggards while penalizing those that have already
invested in meeting existing requirements. For instance, commenters asserted repeal
would change the value for members' credit contracts that have already been negotiated
and finalized, such as for MY 2026. By purporting to destroy the value of those credits,
commenters assert, the proposal unlawfully and retroactively interferes with EV
manufacturers' economic interests.
Commenters also stated that to the extent a court determines that this rule "upsets
expectations" and is not otherwise invalidly retroactive, the EPA also arbitrarily and
capriciously fails to balance the benefits of retroactive rulemaking with burdens on
regulated entities.
EPA Response
The EPA disagrees that the rescission and repeals are retroactive or impermissible. This
final action does not attach new legal consequences to completed events. See section
IV.A.1 of the final action preamble for further discussion. Comments concerning"reliance
interests" are addressed in section IV.A.2 of the final action preamble and in section 1.3.3
of this document.
1.3 Change in Position Doctrine
1.3.1 Acknowledgement of Change in Position
EPA Summary of Comments
Many commenters agreed that the EPA should change its position on all or some of the
legal, policy, and scientific determinations underpinningthe 2009 Endangerment Finding
and GHG emission standards for new motor vehicles and engines under CAA section
202(a)(1). Several of these commenters referenced specific prior positions that the EPA
acknowledged and proposed to change and urged the Agency to finalize the new position.
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Conversely, other commenters argued that the EPA had not acknowledged that it was
changing its position in all or only in some particular respects.
EPA Response
The EPA acknowledged at proposal that the bases for rescission and repeal marked a
significant change in position from positions taken by the Agency in its prior actions and
satisfied the legal requirement to acknowledge and grapple with such change. Further
discussion of relevant prior positions for which we are finalizing a new position is available
throughout the final action preamble. This subsection summarizes and responds to
particular adverse comments on this aspect of the change in position doctrine.
EPA Summary of Comments
A number of adverse commenters asserted that the EPA did not acknowledge all of the
relevant changes in policy and interpretation and alleged inconsistencies between the
proposal and previous statements by the Agency and by courts in judicial opinions.
EPA Response
As discussed in section IV of the final action preamble, the EPA acknowledges that
rescinding the 2009 Endangerment Findingand repealingthe GHG emission standards
involves significant changes to the legal interpretations adopted in the Endangerment
Finding and retained in subsequent actions. See section IV of the final action preamble for
responses to several comments on this topic and additional discussion of the Agency's
prior positions, in contrast to the positions finalized in this action, in the appropriate
section of the final action preamble discussing each issue. The EPA notes that many
comments asserting failure to acknowledge particular changes or prior statements with
respect to certain policy and scientific issues are no longer relevant and outside the scope
of this final action because the Agency is not finalizing several of the potential bases raised
at proposal. For discussion of the proposed bases the EPA is not finalizing at this time, see
section VI of the final action preamble and section 3 of this document.
Agencies are free to change their existing policies so long as they provide a reasoned
explanation for the change, display awareness that they are changing positions, and
consider reliance interests. FDA v. I/I/ages & White Lion Invs., LLC, 604 U.S. 542, 568 (2025).
Additionally, "when an agency rescinds a prior policy, its reasoned analysis must consider
the 'alternatives' that are within the ambit of the existing [policy]]". DHS. v. Regents of the
Univ. of Cat., 591 U.S. 1, 30 (2020) (quoting Motor Vehicle Mfrs. Ass'n v. State Farm Mut.
Auto. Ins. Co., 463 U.S. 29,51 (1983)). When its new policy rests on factual findings that
contradict those which underlay its prior policy, or when its prior policy has engendered
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serious reliance interests that must be taken into account, the agency must provide
additional justification for the changed position as part of its reasoned explanation. Id. at
30-32 (citing Encino Motorcars, LLC v. Navarro, 579 U.S. 211, 221-22 (2016) and FCC v. Fox
TV Stations, Inc., 556 U.S. 502, 515 (2009)). If the agency is not relying on new facts or
evidence to support its new position, it may reevaluate which policy would be better in light
of the existing record. Nat'lAss'n of Home Builders v. EPA, 682 F.3d 1032,1038 (D.C. Cir.
2012).
The EPA acknowledged at proposal, and acknowledges in this final action, that the
rescission and repeals involve a different interpretation of CAA section 202(a)(1) and other
relevant statutory provisions bearing on the best reading of the Agency's statutory
authority. The Agency is finalizing, largely as proposed and after considering comments
bearing on statutory interpretation, that the best reading of the statute does not authorize
the EPA to prescribe new motor vehicle and engine emission standards for GHGs in
response to global climate change concerns. This interpretation marks a change from the
view adopted in the 2009 Endangerment Finding of the statute and the requirements of
relevant judicial decisions, and which the Agency previously retained and defended in
promulgating GHG emission standards since 2009. See sections IV and V.A of the final
action preamble for further discussion.
The EPA further acknowledges that the view of the applicability and consequences of the
MQD with respect to CAA section 202(a)(1) that the Agency is finalizing after considering
relevant comments marks a change from the view taken in the 2009 Endangerment Finding
and subsequent standards rulemakings, including the most recent set of GHG emission
standards rulemakings in 2024 that post-dated the Supreme Court's decision in West
Virginia v. EPA, 597 U.S. 697 (2022). In those actions, the Agency rejected commenters'
MQD concerns, asserting that the MQD does not apply to actions under CAA section 202(a)
and takingthe position that regulating GHG emissions, includingthrough standards that
contemplate increasing adoption of EVs, was a matter clearly delegated to the EPA, not a
novel use of statutory authority, and not a matter of economic or political significance. E.g.,
89 FR 29468-71 (Apr. 22, 2024); 89 FR 27897-900 (Apr. 18, 2024). The Agency is finalizing a
new position that the MQD does apply to the EPA's assertion of authority to regulate new
motor vehicle and engine GHG emissions in response to global climate change concerns,
includingthrough standards that contemplate forcing an increasing adoption of EVs, and
that Congress has not clearly authorized the EPA to decide such questions. As part of this
new position, the Agency is necessarily finalizing a different view of the MQD as articulated
by the Supreme Court in West Virginia and a different view from that espoused in the
Endangerment Finding with respect to the Court's treatment of FDA v. Brown & Williamson
Tobacco Corp., 529 U.S. 120 (2000), in Massachusetts v. EPA, 549 U.S. 497 (2007). See
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sections IV and V.B of the final action preamble and section 2.1.2 of this document for
further discussion.
Finally, the EPA acknowledges that it has not, since the 2009 Endangerment Finding, taken
the position that the inability of GHG emission standards to result in public health and
welfare benefits with respect to global climate change concerns in any material, non-de
minimis way informs the scope of its statutory authority or is relevant to the
reasonableness of the resulting standards. As discussed in section V.A and V.C of the final
action preamble, the Agency is finalizing that its prior consideration of this issue was
incomplete and erroneous. The Endangerment Finding considered questions related to
standards to be out of scope, and subsequent GHG emission standards rulemakings did
not analyze the question in the way the Agency now believes to be appropriate and
necessary in this final action.
For example, several of the earliest GHG emission standards rulemakings in 2010-2012
modeled the potential beneficial impacts of the standards but applied a different legal and
analytical framework.2 At a high level, the modeling demonstrated that the predicted
impacts on climate endpoints were admittedly "small" but were at least susceptible to
modeling in the sense that the Agency could repeatedly produce a number using the
model. The Agency concluded that any quantum of reduction in the selected endpoints
suggested a reduction in adverse risks, although the EPA admitted in those analyses that it
had not estimated risk. In other words, the Agency assumed that any number, no matter
how small or uncertain, indicated risk reduction without quantifying the overall risk to be
reduced. These exercises did not model the scenarios the EPA considered forthis action
and did not analyze whether, given applicable legal principles, it was permissible or
appropriate to assume that any positive number meant a material, non-de minimis impact.
Further GHG emission standards rulemakings did not continue with such modeling and
instead applied Social Cost of Carbon (SCC) methodologies in an attempt to monetize the
benefits of GHG emission reductions for Regulatory Impact Analysis (RIA) purposes. In this
final action, the EPA is reaching different conclusions under an analytical framework the
2 See "Light-Duty Vehicle Greenhouse Gas Emission Standards and Corporate Average Fuel Economy
Standards," 75 FR 25324, 25496 (May 7, 2010) (explaining that the analysis was "intended to quantify these
potential reductions" and acknowledging that the effects of the rule "show small differences in climate
effects (C02 concentration, temperature, sea-level rise, ocean pH)"); "Greenhouse Gas Emissions Standards
and Fuel Efficiency Standards for Medium- and Heavy-Duty Engines and Vehicles "76 FR 57106, 57300 (Sept.
15,2011) (acknowledging "small" impact but concluding risks would be reduced although "these risks were
not formally estimated for this action"); "2017 and Later Model Year Light-Duty Vehicle Greenhouse Gas
Emissions and Corporate Average Fuel Economy Standards," 77 FR 62624, 62898 (Oct. 15, 2012)
(conceptualizing risks "over thousands of years "acknowledging "small" impact, and again concluding risks
would be reduced although "these risks were not formally estimated for this action").
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Agency now believes is more consistent with the statute and applicable law. See section
V.C of the final action preamble and section 2.2 of this document for further discussion.
The EPA further disagrees that changing the legal positions underlying the 2009
Endangerment Finding and subsequent GHG emission standards rulemakings imposes an
obligation to reproduce and respond to every particular prior statement made by the
Agency anywhere such a statement appears. Rather, the change in position doctrine
requires that "when an agency acts 'inconsistently]' with an 'earlier position,' performs 'a
reversal of [its] former views as to the proper course,' or 'disavow[s] prior 'inconsistent'
agency action as 'no longer good law,"' it must" 'display awareness that it is changing
position.'" I/I/ages & White Lion, 604 U.S. at 569-70 (citations omitted). Based on the volume
and content of the comments received, there can be no doubt that at proposal, and in this
final action, the EPA displayed and is displaying an awareness that it is changing position
on the legal framework adopted in the 2009 Endangerment Finding and subsequent new
motor vehicle and engine GHG emission standards rulemakings by adopting a different
position that the Agency concludes reflects the best reading of the statute and applicable
law. Moreover, based on the volume and content of the comments received, there can be
no doubt that at proposal, and in this final action, the EPA displayed and is displaying an
awareness that it is changing position on the Agency's approach to the relevance and legal
implications of the futility of GHG emission standards. To note, the models the EPA used in
illustrating potential impacts on global mean surface temperature (GMST) and global sea
level rise (GSLR) are not new and are generally accepted for purposes of evaluated impacts
under the causal chain endorsed in the Endangerment Finding. Rather, the Agency is using
these existing models to evaluate different scenarios and reach new legal conclusions
about its statutory authority and the legality of GHG emission standards.
Finally, the EPA notes that comments raising concerns that the EPA did not appropriately
acknowledge or explain a change in position with respect to proposed bases that the
Agency is not finalizing at this time are outside the scope of this final action. Several
commenters also raised concerns regarding programs and positions that the EPA did not
propose to reopen or amend and is not amending in this final action. See additional
discussion in the final action preamble and throughout this document for summaries and
responses regarding claims that this new position implicates additional programs that the
EPA did not propose to amend and is not amending in this final action.
For these reasons and those set out in the final action preamble, the EPA believes that this
final action meets the legal standard for a change in agency position.
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1.3.2 Reasons for Changing Position
EPA Summary of Comments
While many commenters endorsed all or some of the EPA's proposed changes in position,
others argued that the Agency provided inadequate orimproperjustificationsforthe
change. For example, several of these commenters asserted that a change in presidential
administration is not a sufficient basis for changing legal interpretation and policy within
the boundaries of the statute. These commenters asserted that the results of the
presidential election did not change the wording or legal interpretation of any law Congress
passed before the election, and that arguments based on policy and politics have no
relevance to the interpretation of what they asserted are the unambiguous statutory
provisions at issue here.
Commenters also stated that inferences from elections or opinion polls should not form
the basis for EPA decisions and that Congress passed laws governing the activities of the
Executive Branch to minimize partisan influences on regulations and enforcement of the
law. While the EPA can re-evaluate its prior decisions, these commenters asserted, the
proper federal pre-2025 procedures for conducting the reevaluation and development or
rescission of federal regulations need to be followed. Commenters asserted that the EPA
Administrator should be briefed on the proper use and role of science, history of scientific
knowledge, and regulatory powers and procedures. Commenters alleged that the pre-2025
federal process includes using only peer-reviewed study reports, building on prior
consensus science documents, participation by science experts in all relevant fields
(including environmental health epidemiologists, environmental health epidemiologists,
system theory experts, and environmental economists) selected by non-federal
professional groups, meaningful solicitation of public comment, and avoidance of making
scientifically untestable statements. Live forums, discussions, and peer-reviewed reports
should be part of the process, these commenters stated, because the comment
capabilities on regulations.gov make it difficult to read relevant comments. The
commenters asserted that the EPA must evaluate the comprehensive human health and
welfare costs and benefits.
Finally, some commentators suggested that certain public statements by the Administrator
and other Agency officials, including in press communications and congressional
testimony, demonstrate improper prejudgment or bias with respect to all or some aspects
of the decision-making processes forthis rulemaking. Other comments point to Executive
Orders and an OMB memorandum as demonstrating prejudgment.
EPA Response
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The EPA disagrees that at proposal, or in this final action, the Agency relied or is relying on
the change in Administration as the sole basis of authority to reconsider its prior actions.
Rather, in stating this basis and citing applicable authorities, the EPA sought to emphasize
that the democratic process is an indelible part of the Nation's constitutional system. The
American people are entitled to have a voice in the laws and regulations that govern them
and impact everyday life, including here, by impacting affordability and restricting
consumer choice in the name of addressing global climate change concerns. That voice is
exercised under Article I through electing representatives to Congress and through Article II
by electing presidential administrations with different views on how to exercise the
responsibilities entrusted to the Executive Branch and faithfully execute the laws.
Moreover, that voice must be considered when the Agency takes actions covered by CAA
section 307(d), which requires soliciting and respondingto public comment and providing
the opportunity for public hearing.
The EPA agrees that the scope of its authority is determined by the laws enacted by
Congress, here, in the CAA. This Administration has prioritized close adherence to
statutory and constitutional limits on agency authority and is committed to reconsidering
prior actions, when appropriate, to ensure regulatory requirements are consistent with the
best reading of the statute and applicable law. As explained in section V of the final action
preamble and this document, the EPA is finalizingthat Congress did not authorize, or, at a
minimum, did not clearly authorize, the Agency to undertake the course of regulation under
CAA section 202(a)(1) initiated by the 2009 Endangerment Finding in response to global
climate change concerns and that the futility of GHG emission standards in addressingthe
health and welfare risks identified in the Endangerment Finding confirms this lack of
authority and, separately, renders retaining the GHG emission standards unreasonable
under settled principles of administrative law.
Accordingly, the EPA disagrees with commenters to the extent they suggest that particular
views of science bearing on global climate change concerns are entitled to supersede
ordinary principles of statutory interpretation, enlarge the Agency's statutory authority, or
are otherwise outside the ambit of the democratic process. As explained in section IV of
the final action preamble and in this document, the EPA has authority to reconsider prior
actions, including to ensure consistency with the law. The EPA is not, as explained in
section VI of the final action preamble and section 3 of this document, rescinding the 2009
Endangerment Finding or repealing the new motor vehicle and engine GHG emission
standards based on the alternative proposed bases for rescission, including based on new
findings by the Administrator with respect to climate science under CAA section 202(a)(1).
Rather, the EPA is finalizing that CAA section 202(a)(1) does not encompass the regulation
of GHGs in response to global climate change concerns, such that the Agency lacks
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authority to resolve such questions for regulatory purposes or to issue or retain GHG
emission standards for new motor vehicles or engines. To note, the Agency's futility basis
for rescission and repeal does not turn on a discretionary weighing of costs and benefits,
but on a conclusion that the Endangerment Finding and resulting GHG emission standards
do not yield material, non-de minimis benefits for public health and welfare with respect to
global climate change concerns.
The EPA further disagrees with commenters' suggestions that the rulemaking process for
this action is a departure from procedures followed prior to 2025. Rather, the Agency has
complied with the applicable rulemaking procedures set out in CAA section 307(d). The
EPA notes that the Administrator requested and received briefings on relevant scientific,
policy, legal, and regulatory issues in developing the proposal, that the comment period
included an extensive public hearing with testimony from a variety of perspectives, and
that this final action is informed by extensive public input and consultations reflected in the
docketforthis rulemaking. See section II.C.1 of thefinal action preamble and section 7 of
this document for further discussion.
With respect to the concern that regulations.gov makes it difficult to evaluate relevant
comments, the EPA notes that the public comment period is intended to offer an
opportunity to respond to the issues raised in the Agency's proposal and supporting
materials rather than to the content of other public comments. As noted at proposal, the
Agency and Federal government at large have resources available to assist interested
members of the public in reviewing and commenting on proposed actions.
Finally, the EPA disagrees with any suggestion that public statements by the Administrator
or other EPA officials are relevant to this final action or demonstrate impermissible bias,
pretext, prejudgment, or a closed mind. Rather, the EPA evaluated all relevant statutory and
regulatory authority and obligations and evaluated the public response to the proposed in
arriving at the conclusions reached in this final action. The EPA is finalizingthis action
under the authorities and for the reasons set out in the final action preamble, and no
others. See sections 6.10 and 7.5 of this document for further discussion.
EPA Summary of Comments
Commenters stated that the EPA is proposing to repeal a policy supported by
"overwhelming" scientific evidence developed over decades. When reversing a policy,
these commenters stated, the EPA must provide a "more detailed justification than would
suffice for a new policy written on a blank slate" if the "new policy rests upon factual
findings that contradict those which underlay its prior policy." Fox, 556 U.S. at 515.
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Several commenters stated that under Massachusetts, any change in policy must be based
on scientific evidence, not policy preferences. These commenters argued that the Supreme
Court made clear that the EPA cannot consider policy factors beyond public health and
welfare when making endangerment determinations. Some of these commenters argued
that the Supreme Court's decision in Loper Bright Enterprises v. Raimondo, 603 U.S. 369
(2024), reinforces this limitation, confirming that agency discretion must operate within
established statutory boundaries focused on science-based health determinations.
Commenters alleged that the EPA has not addressed its prior findings regarding
endangerment in certain actions since the 2009 Endangerment Finding, including 2010 and
2022 denials of petitions for reconsideration, as well as statements made in the new motor
vehicle and engine GHG emission standards rulemakings. According to commenters, those
findings provided significant additional scientific and technical evidence regarding
endangerment beyond what the Agency considered in the Endangerment Finding.
Commenters further stated in an unreported opinion, the U.S. Court of Appeals forthe
District of Columbia Circuit (D.C. Circuit) addressed the EPA's denial of the 2022 petitions
for reconsideration (in addition to the 2010 petitions rejected by the EPA and reviewed in
Coalition for Responsible Regulation, Inc. v. EPA, 684 F.3d 102 (D.C. Cir. 2012)). Concerned
Household Elec. Consumers Council v. EPA, 2023 WL 3643436 (D.C. Cir. 2023). Although
these commenters acknowledged that the court dismissed the challenge to the 2022
denials for lack of standing, they asserted nevertheless that the EPA must explain why only
three years earlier it found in rejecting the petitions for reconsideration that the scientific
and technical arguments raised were "inadequate, erroneous and deficient."
EPA Response
As explained in section VI of the final action preamble, the EPA is not rescinding the 2009
Endangerment Finding orthe new motor vehicle and engine GHG emission standards
based on the alternative proposed bases for rescission, including based on new findings by
the Administrator with respect to climate science under CAA section 202(a)(1). Rather, the
EPA is finalizing that CAA section 202(a)(1) does not encompass the regulation of GHGs in
response to global climate change concerns, such that the Agency lacks authority to
resolve such questions for regulatory purposes or to issue or retain the GHG emission
standards. As explained at proposal and in the final action preamble, the EPA is takingthe
opportunity to clarify that given these conclusions, the 2010 and 2022 reconsideration
petition denials no longer present the Agency's views and should not be relied on as
authoritative. Comments on the proposed science basis referenced above are outside the
scope of this final action because the EPA is not finalizing that basis for rescission or
repeal. However, in the interest of transparency and public engagement only, the EPA
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provides additional information related to comments received on the proposed science
basis and other proposed bases that the Agency is not finalizing in section VI of the final
action preamble.
EPA Summary of Comments
Commenters stated that the EPA does not reconcile its claims at proposal that motor
vehicles do not contribute to endangerment with prior rulemakings involving other air
pollutants, in which the Agency found that stationary sources with smaller emission
contributions "significantly contribute" to dangerous pollution for purposes of regulation
under CAA section 111. Commenters cite to a handful of stationary source regulations in
which the Agency issued emission standards for certain source categories that contributed
relatively low percentages to total national emissions, ranging from approximately five
percent to one percent (with one example, for lead emissions by the lead-acid battery
manufacturing source category, amounting to much less than one percent of national
emissions). See, e.g., 38 FR 15,406 (June 11,1973); 42 FR 22,506, 22,507 (May 3,1977); 42
FR 53,782, 53,783 (Oct. 3, 1977); 44 FR 49,222 49,223-24 (Aug. 21, 1979); 47 FR 16,564,
16,570 (Apr. 16, 1982); 56 FR 24,468, 24,473 (May 30, 1991). Commenters also stated that
the EPA did not adequately justify its apparent departure from its approach in its 2016 GHG
endangerment findingfor aircraft engines. See 81 FR 54422 (Aug. 15, 2016). In makingthat
endangerment finding under CAA section 231, commenters explained, the EPA reiterated
the legal conclusion regarding CAA section 202(a) made in the 2009 Endangerment Finding
and grounded its approach to its legal conclusions regarding CAA section 231 in the
legislative history of CAA sections 202 and 231. Id. at 54435-36. Commenters stated that
as both CAA sections 231 and 202 were provisions included in the 1977 amendments to
the CAA, the Agency's discussion of the history of CAA section 202 and how it supports the
EPA's approach is also relevant for CAA section 231. Id. On that basis, commenters
asserted that the EPA's interpretation of section 231 is the same as its interpretation of the
parallel language in section 202(a), which is explained in the 2009 Endangerment Finding.
Commenters contend that the NPRM does not explain or justify how or why the EPA is
departing from this approach, outlined in the 2016 aircraft endangerment finding.
EPA Response
As discussed in section IV.A of the final action preamble and elsewhere in this document,
the EPA acknowledges that rescinding the 2009 Endangerment Finding and repealing
subsequent GHG emission standards involves significant changes to the legal
interpretations adopted in the Endangerment Finding and retained in subsequent actions.
The EPA believes that the thorough explanation of the legal bases underpinning the
rescission of the 2009 Endangerment Finding in the final action preamble meets its burden
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of acknowledging the Agency's change in position, providing reasonable explanation for the
new position, and consideration of legitimate reliance interests in the prior position.
As to commenters' statements related to stationary sources and aircraft regulations,
commenters are comparing different programs that fall under different statutory
provisions and are informed by different contexts. As noted at proposal, this action is
limited to the 2009 Endangerment Finding and related GHG emission standards
promulgated under CAA section 202(a)(1). See 90 FR 36298. Commenters do not appear to
suggest, and identify no legal authority for the proposition that, the EPA may not address
issues on a subject-by-subject basis consistent with the authorities and procedures
provided in the CAA. There is no requirement for the EPA to resolve all issues related to
GHG emission standards within one regulatory action, especially when those actions are
not within the same provision of the CAA.
With respect to commenters' statements regarding the EPA's 2016 GHG endangerment
finding for aircraft, commenters do not identify any material respect in which that 2016
decision staked out a different position than, or offered substantially different rationale for,
the legal and analytical framework adopted with respect to CAA section 202(a)(1) in the
2009 Endangerment Finding and retained in subsequent new motor vehicle and engine
GHG emission standards. Rather, that 2016 decision noted the bases the Agency had
developed for CAA section 202(a)(1) and added additional considerations specific to CAA
section 231 that are not relevant to this rulemaking under CAA section 202(a)(1). As
explained in the final action preamble, and consistent with the proposal, the EPA is now
finalizing a new position on CAA section 202(a)(1) that differs from that adopted in the
Endangerment Finding and retained in subsequent actions. This change was discussed
and presented for comment in the proposal, 90 FR 36298, and is supported by the legal
rationales now finalized, largely as proposed, in section V of the final action preamble.
With respect to commenters' contention that the EPA previously found significant
contribution based on smaller emission contributions from stationary sources under CAA
section 111, the EPA notes that this final action is not predicated on a new determination
with respect to the share of contribution by new motor vehicles and engines. As explained
in section VI of the final action preamble, the EPA is not rescinding the 2009 Endangerment
Finding based on the alternative proposed bases for rescission, including based on new
findings by the Administrator with respect to climate science under CAA section 202(a)(1).
Rather, the EPA is finalizing that CAA section 202(a)(1) does not encompass the regulation
of GHGs in response to global climate change concerns, such that the Agency lacks
authority to resolve such questions for regulatory purposes or to issue or retain GHG
emission standards for new motor vehicles or engines. Comments on the proposed
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science basis referenced above are outside the scope of this final action because the EPA
is not finalizingthat basis for rescission or repeal.
See section 2.2.3 of this document for additional discussion.
EPA Summary of Comments
Commenters stated that the EPA, in proposing as part of its "integrated" interpretation of
CAA section 202(a)(1) that the Agency must consider harms from each of the six "well-
mixed" GHGs separately, should have addressed other instances in which the Agency
groups related pollutants together for analytical or regulatory purposes. According to
commenters, the EPA's longstanding approach has been to group and analyze related
pollutants together for CAA purposes.
EPA Response
The EPA disagrees with these comments, which misstate the nature of the argument as
relevant to the bases for rescission and repeal finalized in this action. See section 2.1.1.3.5
of this document for further discussion.
EPA Summary of Comments
Commenters stated that the EPA's reliance on the example of water vapor to bolster what
they construed as the Agency's new "contribution" interpretation ignores the EPA's explicit
rejection of that argument in the 2009 Endangerment Finding.
EPA Response
The EPA disagrees with these comments, which misstate the nature of the argument as
relevant to the bases for rescission and repeal finalized in this action. The EPA did not
"reject" the possibility of regulating water vapor as a "climate forcer" in the 2009
Endangerment Finding, but rather declined to do so at that time and indicated an intent to
consider the issue further. See section V. A.I of the final action preamble and section
2.1.1.1.5 of this document for further discussion.
EPA Summary of Comments
Commenters stated that the EPA cannot rely on the MQD to support its changed position,
which they construed as concluding that CAA section 202(a) excludes pollutants with
global effects. These commenters argued that the Supreme Court's decision in
Massachusetts made clear that the MQD does not apply here.
EPA Response
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The EPA disagrees with these comments, which misstate applicable law. See section V of
the final action preamble and section 2.1.2.1 of this document for further discussion.
EPA Summary of Comments
Commenters stated that the EPA does not explain why it no longer believes treating the
entire fleet of vehicles as a reasonable surrogate for newvehicles is no longer persuasive or
reasonable.
EPA Response
The EPA disagrees with these comments, which misstate the nature of the argument and
fail to grapple with CAA section 202(a)(1 )'s application to only "new" motor vehicles and
engines. See section 2.1.1.3.6 of this document for further discussion.
1.3.3 Reliance Interests
EPA Summary of Comments
The EPA received a variety of comments on the relevance and nature of reliance interests
with respect to the proposed rescission of the 2009 Endangerment Finding and repeal of
subsequent GHG emission standards. Comments ranged from arguments that reliance
interests are not relevant to changing legal interpretation to reflect the best reading of the
statute to arguments that particular reliance interests must be considered and counsel
against, or require, not finalizing any rescission or repeals or finalizing only certain aspects
of the proposed rescission and repeals.
Some commenters asserted that reliance interests are irrelevant when assessing whether
to rescind an action that the EPA lacked statutory authority to take, arguing that no amount
of reliance could justify continuing a program that allows the Agency to wield power that
neither Congress nor the Constitution gave it.
Separately, commenters also argued that regulated entities do not have "significant
reliance interests" in the GHG emission standards because repeal would give regulated
parties more options. These commenters noted that manufacturers can still implement
their GHG emission standard plans and designs as currently drawn up if they choose to do
so.
Conversely, other commenters argued that regulated parties have a reliance interest in
operatingtheir industries (including those related to new motor vehicles and engines) in a
stable regulatory landscape. These commenters asserted that such a landscape exists
here and has been built on at least 15 years of established practice. Commenters
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additionally stated that significant research and development resources have been spent
to meet these regulations and those would be lost if the regulations were eliminated.
Commenters stated that the EPA failed to consider relevant reliance interests involving the
U.S. economy, national security, global political impacts, and global trade impacts. The
EPA must account for these reliance interests, commenters asserted, and its failure to do
so renders the proposal arbitrary and capricious.
Commenters also stated that all Americans, including consumers, have reliance interests
in the 2009 Endangerment Finding and GHG emission standards because repeal will
directly affect their public health, welfare, and security. These commenters argued that the
EPA had not adequately considered such interests or implications for the U.S. economy,
national security, global geopolitics, and global trade. According to these commenters,
citizens have relied on protections provided through what they construed as the
congressionally mandated protection from GHGs and the harm from climate change.
Still other commenters stated that state and regional programs as well as environmental
and public health advocacy groups have built strategies and legal arguments around the
stability of the Endangerment Finding, which has served as the "legal bedrock" for climate
regulations for 15 years.
EPA Response
As discussed in section IV.A.2 of the final action preamble, the EPA agrees with the
suggestion that reliance interests are irrelevant when assessing whether to rescind an
action that the Agency lacked statutory authority to take because no amount of reliance
could justify continuing a program that allows the Agency to wield power that neither
Congress nor the Constitution confers. Given the conclusions reached in this final action,
retaining the program for any additional period, or finalizing what would amount to the
promulgation of revised regulations that include a ramp down or phase out, would exceed
the Agency's statutory authority. The EPA is not aware of, and commenters did not identify,
any statutory authority or settled legal principle that would authorize the Agency to finalize
such actions absent statutory authority under CAA section 202(a)(1).
Nevertheless, as discussed in the final action preamble and in this document, the EPA
reviewed and considered reliance interests raised by stakeholders in the interest of
transparency and public engagement. None of the reliance arguments raised by
commenters suggested a reason that reliance interests, even if significant and cognizable,
can serve to confer the EPA additional authority to retain the Endangerment Finding or
related GHG emission standards notwithstanding the Agency's conclusion that CAA
section 202(a)(1) does not authorize the regulation of new motor vehicles and engines in
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response to global climate change concerns. Nor did commenters identify an alternative
statutory authority that could serve as a basis for retaining the Endangerment Finding or
GHG emission standards absent authorization under CAA section 202(a)(1).
As discussed in section IV.A.2 of the final action preamble, the EPA agrees with
commenters asserting that this final action relieves compliance obligations under the CAA
and does not require anything further of regulated parties with respect to GHGs. In other
words, consistent with the proposal, this final action expands the range of choices
available to regulated parties rather than restricting such choices. The EPA recognizes the
general interest on the part of regulated parties in a stable regulatory structure, particularly
in the context of new motor vehicle and engine manufacturing, which involves a MY-by-MY
cycle, substantial research and development, and significant supply chains. However,
while not a basis for this final action, the Agency believes that the rescission and repeals
further, rather than undermine, the asserted interest in regulatory stability. As a result of
this final action, the EPA is removing and will no longer prescribe GHG emission standards
in response to global climate change concerns under CAA section 202(a)(1). Regulated
parties will no longer need to participate in GHG emission standard rulemakings, plan in
anticipation of future rulemakings, including by anticipating or participating in the
uncertainties of judicial review, or comply with GHG emission standards. At the same time,
the regulatory structure respecting emission standards for air pollution within the ambit of
CAA section 202, including criteria pollutants and air toxics, remain in place.
As articulated in section IV.A.2 of the final action preamble, the alleged negative impacts to
public health, welfare, security, the general economy, global geopolitics, and global trade
are not the type of specific, cognizable, and legitimate reliance interests that could or must
be taken into account as reliance interests in this rulemaking. Case law provides that such
general interests are not the type of reliance interests that require special consideration.
Where relevant and appropriate, the EPA has taken such considerations into account in
assessing and applying the statutory language of CAA section 202(a)(1) and related
provisions. Moreover, the asserted strategic and legal interests of advocacy groups in the
stability of the Endangerment Finding are not significant or legitimate reliance interests that
the Agency needs to account for in this rulemaking. As the Supreme Court recently
articulated in FDA v. Alliance for Hippocratic Medicine, organizations cannot establish
legally cognizable harm "simply based on the 'intensity of [their] interest' or because of
strong opposition to the government's conduct, 'no matter how longstanding the interest
and no matter how qualified the organization.'" 602 U.S. 367, 394 (2024) (citations omitted).
Although not necessary, for that reason, to address this point as a reliance interest, the EPA
does not agree with the alleged negative impacts articulated by commenters related to
public health, welfare, and security related to this final action. The EPA discusses the
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benefits and costs of this final action within the preamble and other documents within the
final action docket. Additionally, the Agency could not retain the Endangerment Finding
based on such advocacy group interests absent legal authority to do so under the CAA. Per
Loper Bright, statutes have a single, best reading that is fixed at the time of enactment. The
EPA's final action provides clarity and stability by identifying and applying that single, best
reading.
As explained further in the final action preamble, we endeavored to take these reliance
concerns into account in this rulemaking when appropriate, including by carefully
reviewing and considering the ways in which Congress addressed international emissions
issues in the CAA. However, the controlling statutory language in CAA section 202(a)(1)
does not authorize the Agency to regulate GHG emissions in response to such global
concerns. The possibility that interpreting CAA section 202(a)(1) to authorize regulation in
response to global climate change concerns would render the statute broad enough to
encompass global political and economic relations reinforces our view of the best reading
of the statute.
Finally, we acknowledge that with almost all Federal government regulatory actions, there
will be regulated parties and other market participants that benefit from the action and
regulated parties and other market participants that experience adverse consequences
from the action. Over the course of the EPA's GHG emission standards program for new
motor vehicles and engines, certain regulated parties and other market participants have
captured additional value in the past, while other regulated parties and other market
participants have experienced a relative loss in value in the past. With respect to this final
action, regulated parties that produce GHG emission credits will likely lose the value of
such credit development while regulated parties that would be required to obtain GHG
emission credits for compliance, sell different vehicles at a relative loss, or face risks of
noncompliance will no longer experience such losses.
1.3.3.1 State and Local Governments
EPA Summary of Comments
Comment Topic 1: Climate action plans
Commenters stated that State and local governments have relied on the 2009
Endangerment Finding and/orfederal GHG standards to craft State and local climate
policy, using federal programs as a baseline to determine what measures they identify as
necessary at a State and local level.
These commenters noted that many States and local governments designed and
implemented comprehensive policies to reduce GHG emissions and adapt to anticipated
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climate change impacts, often referred to as climate action plans (CAPs). These CAPs are
frequently developed at the State agency level to implement laws or mandates adopted by
Governors or State Legislatures. For example, commenters noted that Massachusetts
published and regularly updates a Clean Energy and Climate Plan to meet GHG emission
reduction goals under the Massachusetts Global Warming Solutions Act and the Next-
Generation Roadmap for Massachusetts Climate Policy. Commenters also noted that
California developed its 2022 Scoping Plan to meet GHG emission-reduction targets under
SB 32. Commenters cited what they viewed as comparable examples of State agency
responses to State Executive or Legislative responses, including in New Jersey, Oregon,
New Mexico, and New York, and asserted that many other States and local governments
have developed similar plans.
According to commenters, such States and local governments have relied on the
continued existence of the EPA's vehicle and engine GHG standards program in designing
such CAPs. For example, many climate action plans have utilized the EPA's Motor Vehicle
Emission Simulator (MOVES) model, a "state-of-the-science emission modeling system
that estimates emissions for mobile sources at the national, county, and project level for
criteria air pollutants, greenhouse gases, and air toxics." MOVES accounts for
environmental factors, including temperature and humidity, type of fuels available for use,
and the phase-in of federal emission standards over time, thereby incorporating federal
GHG standards to calculate emissions overtime undervarious scenarios. Commenters
asserted that several States, including New Jersey, North Carolina, Oregon, and
Pennsylvania, as well as Washington, D.C., have used MOVES to create GHG inventories or
estimate on-road emissions.
According to commenters, other States, instead of relying on MOVES emissions data, have
made foundational assumptions relying on continued existence of the EPA's GHG emission
standards for vehicles and engines. For example, commenters stated that California's
reference scenario assumptions include the estimated impact of all current regulations as
of Spring 2022. Commenters listed further examples, including from Minnesota, Maryland,
New Hampshire, and Delaware, in which State entities used modeling or analyses that
assumed reductions from the EPA's GHG emissions standards, at least through various
MYs, at times in conjunction with NHTSA fuel-economy standards. Commenters
emphasized their belief that such modeling and analyses played key roles in State and
local CAPs and subsequent actions and that the emission inventories assumed to various
degrees emission reductions anticipated in the EPA's GHG emission standards for the
relevant MYs.
EPA Response
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As further discussed in section IV.A.2 of the final action preamble, while the EPA is aware of
such State and local government actions and initiatives, the EPA disagrees that this final
action disrupts State and local policy initiatives as nothing in this final action changes the
status quo for such initiatives. That is to say, State and local governments may continue
such initiatives to the extent consistent with Federal and State law, and nothing in this final
action restricts or expands the ability of State and local governments to do so or Federal
and State law limitations on their doing so. With respect to comments stating that such
initiatives incorporated emissions reductions data or requirements in prior EPA GHG
emission standards for motor vehicles and engines, the Agency notes that such data and
emissions reductions predictions are still available as an analytical matter. Emissions
reductions required for completed MYs are not expected to change materially, and State
and local entities may adjust such plans as they see fit going forward with respect to
emissions reductions for future MYs that may, or may not, play out as previously
anticipated. State and local governments may choose to adjust legislative or policy
requirements related to such State and local government initiatives, or they may choose to
retain such legislative and policy requirements but implement them differently.
EPA Summary of Comments
Commenters also raised that States have relied on co-pollutant reductions from the EPA's
vehicle GHG standards to attain and maintain the National Ambient Air Quality Standards
(NAAQS). In their most recent submissions for the Northern New Jersey-New-York
Connecticut Nonattainment Area, for example, New Jersey, New York, and Connecticut
relied on the projected emission reduction benefits from the 2024 Multipollutant Rule, the
Phase 3 Greenhouse Gas Standards for Heavy-Duty Vehicles, and MY 2023-26 light-duty
greenhouse gas Standards to attain the 2015 8-hour ozone NAAQS. New Jersey has
similarly relied on the emission reduction benefits from the MY 2023-26 light duty GHG
standards to attain the 2006 24-hour PM2.5 NAAQS. Commenters asserted that without
the aid of vehicle GHG standards, some States would have to take additional actions and
expend significant resources. For example, the California Air Resources Board (CARB)
reports that it spends up to $33,000 to mitigate a single ton of nitrous oxides (NOx)
emissions in California. As another example, commenters stated that because States
depend on early planning to reduce the costs of compliance, changes in Federal regulatory
approaches that significantly increase criteria pollutant emissions can be costly and
disruptive to the States, as well as to regulated industries within those States.
According to commenters, several States also have relied on the new motor vehicle and
engine GHG emissions program to project the efficacy of proposed control measures in
their Ozone NAAQS State Implementation Plan (SIP) updates. States in the
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MidAtlantic/Northeast Visibility Union ("MANE-VU") - Connecticut, Delaware, District of
Columbia, Maryland, Massachusetts, New Jersey, and New York- have utilized emissions
inventories to project NOx emissions within their geographic areas through the year 2028 as
part of their efforts to comply with the Ozone NAAQS. These emissions projection systems,
in turn, rely on the MOVES model. Pennsylvania has relied on the EPA's MOVES model, and
the federal vehicle regulations it incorporates, to revise its State NOx motor vehicle
emission budget. Colorado has similarly utilized the EPA's MOVES model to create its SIPs
for its moderate and severe ozone nonattainment areas. And, according to commenters, no
fewer than 15 States' Regional Haze SIPs have relied on the EPA's MOVES model to project
emissions reductions resulting from federal vehicles regulations by 2028 to inform their
strategies to comply with federal regional haze requirements.
Commenters stated that reducing reductions for NOx and PM will interfere with
metropolitan planning organizations' abilities to demonstrate conformity with the motor
vehicle emission budgets adopted as part of their air quality planning process to
implement the transportation conformity requirements of the CAA. According to
commenters, metropolitan planning organizations must demonstrate that emissions from
the transport system in a metropolitan area must comply with applicable emission budgets
for 20 years. Commenters asserted that metropolitan planning organizations will not be
able to demonstrate conformity and risk the loss of federal highway funding if emission
budgets were based on expected reductions that may not materialize because of the
repeal of the vehicle standards for GHG emissions.
EPA Response
As further discussed in section IV.A.2 of the final action preamble, while we acknowledge
that many regulated parties elected to comply with the GHG emission standards using
technologies that also produce reductions in criteria pollutant emissions, we disagree that
such co-benefits engender significant reliance interests relevant to this rulemaking or that
such considerations justify retaining the GHG regulatory program in the absence of
statutory authority, particularly because the EPA has additional, express statutory
authorities to address criteria pollutant emissions relevant to NAAQS attainment.
As a practical matter, criteria pollutant emission reductions attributable to the GHG
emissions standards are small in absolute terms and unlikely to materially impact States'
attainment of the NAAQS. And any criteria pollutant emission reductions realized in
practice as a co-benefit of GHG emission standards for MY 2025 and earlier are not
impacted by this final action. Moreover, this final action does not require regulated parties
to change existing plans but rather provides additional flexibility moving forward.
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The EPA notes that claims framing criteria pollutant emission reductions as a co-benefit of
GHG emission standards for new motor vehicles and engines must be understood in the
overall context of CAA section 202, under which the Agency has promulgated separate
emission standards for such criteria pollutants. To the extent commenters believe that
criteria pollutant emission standards should be adjusted to capture additional reductions
for the reasons summarized above, the appropriate place to raise such concerns is future
criteria pollutant emission standards rulemakings. The EPA has already announced future
rulemakings with respect to new motor vehicle and engine criteria pollutant emission
standards for upcoming MYs, and the Agency has regularly updated such standards over
the years. Put another way, because CAA section 202 authorizes, and in certain respects
requires, the EPA to regulate criteria pollutant emissions from new motor vehicles and
engines in particular ways, it would not be appropriate to retain or amend GHG emission
standards solely for the purpose of achieving reductions in criteria pollutant emissions that
are separately regulated under the same statutory authority.
For these reasons, and those more fully discussed in section IV.A.2 of the preamble, while
we do not need to reach the decision on reliance interests, we do not agree that States
have significant reliance interests in the permanence of GHG emission standards in
connection with NAAQS attainment.
EPA Summary of Comments
Commenters noted that State and local governments invested substantial resources in: (1)
the domestic manufacture of zero-and low-emitting vehicles, including investments in
research and development for zero-emission technologies, battery manufacture, critical
minerals mining and processing, and other key segments of clean vehicles' supply chains;
(2) building out their EV charging and alternative fueling infrastructure consistent with a
significant shifttowards zero- and low-emittingvehicles in the national vehicle market,
consistent with automakers' substantial investments in these vehicles as a preferred
compliance strategy under the federal GHG program; and (3) transportation electrification
to secure the environmental and public health benefits from zero-emission technologies
and environmental benefits in consumer savings, grid reliability benefits, and energy
security.
State and local governments provided examples of investments, both public and private, in
clean vehicle manufacturing and supply chains. Commenters asserted that clean vehicle
industries already comprise a substantial part of many States' and local governments'
economies. According to commenters, the States and local governments have anticipated
continued growth throughout the clean vehicles and battery manufacturing sectors in the
comingyears, with substantial anticipated accompanyingjob growth.
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State and local governments also provided examples of investments in charging
infrastructure, asserting that they have invested substantial resources in building out their
EV charging and alternative fueling infrastructure. States and local governments, according
to commenters, have committed significant resources, in terms of time and money, both
through the National Electric Vehicle Infrastructure (NEVI) Formula Program and their own
state and local programs, to build out additional charging infrastructure to accommodate
expected increases in EV makeup in the overall fleet. Several States have added newly
designated EV Alternative Fuel Corridors to bring the total Alternative Fuel Corridor network
to more than 81,000 miles. And, based on the evolving EV market and changes in State
needs and goals, many States further refined their EV infrastructure deployment goals to
engage and coordinate with neighboring States in planning for stations on Alternative Fuel
Corridors at State borders.
According to commenters, certain States and local governments have also committed
substantial amounts of their own funds and provided the following examples in this
comment summary. Through calendaryear 2024, the California Public Utilities
Commission approved over $738 million in spending on infrastructure to support medium-
and heavy-duty electric charging infrastructure, and over $152 million had been spent.
New York is investing nearly $3 billion in electrifying its transportation sector. In May 2023,
Minnesota enacted legislation that provided $13.6 million in funds to match the State's
NEVI funds to help build out EV charging infrastructure. In 2024, Michigan approved a $30
million one-time appropriation to support clean fuel and charging infrastructure projects.
In 2021, Colorado created several new transportation electrification enterprises that will
invest over $730 million in State transportation programs to, among other things, deploy EV
charging and hydrogen fueling infrastructure, deploy zero-emission vehicle (ZEV) transit
buses, and increase fleet adoption of EVs. Colorado has already invested over $107 million
to build and install over 4,000 charging ports throughout the State, and over $300 million
via its EV tax credit to support the purchase of over 80,000 EVs.
EPA Response
As further discussed in section IV.A.2 of the final action preamble, with respect to
commenters' assertions about State and local government investments in EV technology
and infrastructure, the EPA disagrees that such reliance interests counsel against the
rescission and repeals for substantially the same reasons discussed above regarding
regulated parties and other State and local voluntary GHG emission reduction programs.
With respect to EV and EV-related investments in particular, nothing in this final action
eliminates or restricts such investments or the preexisting authority of State and local
governments to implement, maintain, or expand such investments. Separate and apart
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from this final action, predictions about market support for EVs, the economics of EV
production, and EV penetration have already outpaced reality. State and local investments
in EVs and related infrastructure were never guaranteed to produce the benefits the
relevant State and local entities hoped to achieve, and such benefits do not expand the
EPA's authority to prescribe emission standards under CAA section 202(a)(1).
Commenters appear to recognize, at least at some level, that the Federal GHG emission
standards were expected, and intended, to force a rapid transition towards EV manufacture
and utilization in a manner that the market itself would not otherwise support. The EPA
disagrees that this belief is appropriately considered a significant reliance interest given
the object of regulation under CAA section 202(a)(1) - reducing emissions to combat air
pollution that adversely impacts health and welfare, rather than forcing the adoption of
particular technologies. Moreover, the EPA notes that these arguments tend to support the
conclusion, discussed in section V.A of the final action preamble and section 2.1.2 of this
document, that the Agency exceeded its authority in contravention of the major question
doctrine by pursuing GHG emission standards in an effort to force a transition away from
the internal combustion engine and towards EVs.
1.3.3.2 Vehicle Manufacturers
EPA Summary of Comments
Commenters stated that manufacturers and importers selling EVs in the U.S. have already
expended resources to comply with GHG emission standards. According to commenters,
the total investments in facilities already in operation, under construction, and announced
by all businesses up and down the supply chain from 2007 to August 2025 amounts to $211
billion. Commenters asserted that the EPA has not justified why these investments in
reliance on the EPA's GHG vehicle standards should be discarded.
At least one commenter implied that certificates of conformity will be impacted by a
change in standards and that this would prohibit vehicle sale and import, functionally
remove anti-tampering protections, impact warranties based on the time of sale and the
useful life of the vehicle, and complicate written maintenance instructions because all of
this is based on a certification tied to a fixed regulatory target for a motor vehicle's entire
useful life.
Commenters also stated that U.S. manufacturers have invested billions of dollars based on
federal commitments towards reducing GHG emissions. Accordingto commenters, auto
manufacturers have developed and deployed technologies with the purpose of improving
vehicle performance while reducing emissions, including exhaust gas recirculation
systems, after-treatment systems, catalytic converters, idle reduction systems, and
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lightweighting of vehicles. Some commenters asserted that these reliance interests
suggest the EPA should consider a more limited repeal of the 2024 GHG emissions
standards rather than a broader rescission of the 2009 Endangerment Finding.
Commenters also asserted that U.S. automakers have historically been able to
manufacture vehicles that comply with U.S. GHG standards and export many of the same
(or similar) vehicles overseas, knowing that they will generally comply with international
emission standards. The commenters further asserted that automakers will now be subject
to a global patchwork of regulation, requiring complex product-planning and homologation
processes, dual powertrain strategies, inventory splits, and compliance engineering, all of
which raise unit costs and introduce significant risk and complexity.
Other commenters stated that some automakers may claim that they have invested heavily
in EV technology in reliance on the EPA's prior GHG regulations. But, according to the
commenters, the EPA should discount such assertions because (1) the current rule bails
out some automakers' bad EV investments; (2) the automakers' investments predate the
current regulation; and (3) automakers are already retreating from EV production without
the proposed repeal.
EPA Response
As discussed in section IV.A.2 of the final action preamble, reliance interests are irrelevant
when assessing whether to rescind an action that the Agency lacked statutory authority to
take because no amount of reliance could justify continuing a program that allows the
Agency to wield power that neither Congress nor the Constitution confers. Given the
conclusions reached in this final action, retaining the program for any additional period, or
finalizing what would amount to the promulgation of revised regulations that include a
ramp down or phase out, would exceed the Agency's statutory authority. The EPA is not
aware of, and commenters did not identify, any statutory authority or settled legal principle
that would authorize the Agency to finalize such actions absent statutory authority under
CAA section 202(a)(1).
As discussed in the final action preamble, the EPA acknowledges certain regulated parties
invested significantly in EV production and technologies that have been or could be used to
comply with the GHG emission standards. Nothing in this final action precludes market
participants from continuing to make such investments or removes any benefit capable of
engendering cognizable reliance interests. Nor are such investments capable of expanding
the EPA's statutory authority under CAA section 202(a)(1).
In general, the EPA concludes that investments in EVs and related technologies should not
be attributed exclusively to the EPA's current GHG emissions standard requirements. The
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new motor vehicle and engine market is complex and informed by a wide variety of
economic and regulatory considerations. As several commenters recognized, some of
these investments predate our most recent GHG emission standards rulemaking in 2024
for MYs 2027 and beyond, and some predate the Endangerment Finding. With respect to
economic influences, the Agency notes that EV demand has been subject to significant
fluctuation and declines unrelated to this rulemaking. The decline in demand is
attributable in part to Congress, which recently repealed certain tax credits and subsidies
for EVs and disapproved three prior EPA preemption waivers for EV-forcing California
vehicle and engine regulations. Changes in consumer preferences are also relevant
factors. The ability of market participants to earn a return on EV and related investments
relies on a variety of factors that ultimately fall outside the Agency's regulatory
wheelhouse. The CAA requires us to take cost into account in various ways, but it does not
require the EPA to ensure that EV investments turn a profit.
The EPA disagrees that possible challenges facing automakers in complying with
international emission standards are legitimate reliance interests that counsel against the
rescission and repeals, as addressed in the final rule preamble. The Agency questions the
premise that automakers assume their products will comply with applicable emission
standards in export markets, as GHG emission standards are not in place for new vehicles
and engines (or the same classes of new vehicles and engines) in all export markets and
vary significantly among nations where such GHG emission standards are in place and
applicable to imports. The Agency also notes that many automakers structure design,
marketing, and production strategies to account for differing emission standards across
various markets, both for GHG emissions and for emissions of criteria pollutants and air
toxics. Regardless, as discussed above, nothing in this final action prevents regulated
parties from maintaining current plans to the extent that they believe doing so is a
convenient way to more easily participate in export markets.
Contrary to the commenters' suggestion that the alleged reliance interests warrant a
limited repeal of, or revision to, the 2024 GHG emission standards vehicle rule instead of
rescinding the Endangerment Finding, the EPA has no discretion to do so, as discussed in
the final action preamble and elsewhere in this document. Given the conclusions finalized
in this action, which were presented at proposal, and confirmed after considering relevant
comments, the bases on which the EPA is rescindingthe Endangerment Finding also
require the repeal of the associated GHG emission standards. Conversely, application of
the conclusions finalized in this action to the GHG emission standards require rescinding
the Endangerment Finding. Nor have commenters identified a basis to conclude that the
2024 GHG emission standards rested on a different legal interpretation of CAA section
202(a)(1) than earlier GHG emission standards or the Endangerment Finding itself, such
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that the Agency could conclude that one or more of the prior standards rulemakings is
inconsistent with the best reading of the statute while other prior standards rulemakings or
the Endangerment Finding itself is somehow consistent with the best reading of the
statute.
1.3.3.3Greenhouse Gas Compliance Credits
EPA Summary of Comments
Commenters asserted that the EPA proposes to eliminate the value of millions of existing
GHG compliance credits, which companies have accumulated over the past 15 years,
thereby eliminating billions of dollars of value and altering the legal consequences of prior
business transactions. According to commenters, a feature of the existing GHG emission
standards is that manufacturers who exceed compliance requirements can generate
tradeable credits from their overcompliance, creating a financial incentive for investments
in advanced emission-reduction technologies.
Commenters also stated that the EPA should address the narrow issue of reliance tied to
the credit regime. According to these commenters, some firms have booked regulatory
credits as assets, and a sudden elimination without transition could create short-term
balance-sheet shocks. Commenters asserted that while the reliance on credits does not
justify continuation, a brief wind-down can ease transition. Commenters suggested that
the EPA provide a limited phase-out for bookkeeping without prolongingthe underlying
distortions, which, in their view, will smooth repeal and minimize unnecessary disruption.
EPA Response
As discussed in section IV.A.2 of the final rule preamble, reliance interests are irrelevant
when assessing whether to rescind an action that the Agency lacked statutory authority to
take because no amount of reliance could justify continuing a program that allows the
Agency to wield power that neither Congress nor the Constitution has conferred. Given the
conclusions reached in this final rule, retainingthe program for any additional period, or
finalizing what would amount to the promulgation of revised regulations that include a
ramp down or phase out, would exceed the Agency's statutory authority. The EPA is not
aware of, and commenters did not identify, any statutory authority or settled legal principle
that would authorize the Agency to finalize such actions absent statutory authority under
CAA section 202(a)(1).
The EPA has consistently maintained that regulated parties lack a property right in
compliance credits or their use to demonstrate compliance, and the Agency further notes
that the relevant universe of compliance credits potentially impacted by this final action is
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much smaller than some commenters suggest, as credits are specific to compliance years
and expire after five years. See 73 FR 25692 (May 7, 2010) and 40 CFR 86.1865-12(k)(2).
Relatedly, see 40 CFR 86.1861-17(b)(3) (LD and MD vehicle credits); 40 CFR 1036.740(d)
(HD engine credits), and 1037.740(c) (HD vehicle credits). Credits for MY 2020 and previous
vehicles are expired, and potential credits for MY 2026 and beyond vehicles are not yet in
place.
Additionally, adjusting the quantity or value of emission credits or allowances is not new to
the EPA, and has been accomplished in other programs underthe CAA when the Agency
determined that doing so was appropriate to achieving a statutory or regulatory end. For
example, the EPA adjusted the quantity of banked allowances that could be carried over
from one emissions trading program to another in the Cross-State Air Pollution Rule Update
for the 2008 Ozone NAAQS, 81 FR 74504, 74557 (Oct. 26, 2016); see also id. at 74559
(explaining that under the regulations for that trading program, allowances constituted only
a "limited authorization to emit" and "do not constitute property rights"); Wisconsin v. EPA,
938 F.3d 303, 321 (D.C. Cir. 2019) (upholding the allowance-bank conversion as reasonable
exercise of agency discretion).
These considerations lead us to conclude that the impact on stakeholders arisingfrom
compliance credit issues will be relatively small and temporary. More fundamentally, our
lack of statutory authority to retain the GHG emission standards means that we lack
discretion to issue revised regulations that incorporate a phase-out or wind-down
approach to address concerns related to this compliance mechanism. As a practical
matter, comments seem to be suggesting that the EPA retain the market value of
compliance credits (which is determined by market participants and not the Agency) by
revising applicable regulations to retain compliance obligations, including enforcement
mechanisms in the event of noncompliance. Absent such requirements and the risk of
enforcement, there is no reason to believe that the compliance credits would retain value
duringa phase-down period. That would require the EPA to retain, and indeed re-impose,
compliance obligations on regulated parties that the Agency is concluding it lacks statutory
authority to retain or impose in the first instance.
1.3.3.4 Vehicle Purchasers and American Consumers Generally
EPA Summary of Comments
Commenters stated that the EPA failed to recognize the reliance interests of vehicle
purchasers, including States, municipalities, and large businesses with commitments, to
purchase certain numbers of clean vehicles, and that the EPA failed to recognize reliance
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interests of past vehicle purchasers in battery warranty and performance requirements and
in-use GHG emissions requirements.
Commenters also stated American consumers have benefited from and relied upon the
existing GHG standards. The EPA's current GHG standards, according to commenters,
were projected to save consumers thousands of dollars per vehicle in fuel costs over the
life of the car.
Commenters also raised individual decisions made based on climate risk, such as
abandoning a home purchase after learning home flood and wind insurance would be
unaffordable or unavailable and that insurance instability is a worry. Commenters also
noted personal vehicle purchases of EVs and charging infrastructure for their homes that
are substantial costs made in reliance on the Endangerment Finding and expectation of a
national transition to EVs and accompanying infrastructure.
EPA Response
As discussed in section IV.A.2 of the final action preamble, reliance interests are irrelevant
when assessing whether to rescind an action that the Agency lacked statutory authority to
take because no amount of reliance could justify continuing a program that allows the
Agency to wield power that neither Congress nor the Constitution has conferred. Given the
conclusions reached in this final action, retaining the program for any additional period, or
finalizing what would amount to the promulgation of revised regulations that include a
ramp down or phase out, would exceed the Agency's statutory authority. The EPA is not
aware of, and commenters did not identify, any statutory authority or settled legal principle
that would authorize the Agency to finalize such actions absent statutory authority under
CAA section 202(a)(1).
The EPA disagrees that such interests counsel against finalizing the rescission and repeal
and notes that commenters misconstrue the impact of this final action and the
requirements in the GHG emission standards. Nothing in this final action requires
regulated parties to change existing plans, and that logic applies to future purchase
commitments as well. If States, municipalities, or businesses wish to fulfill existing
purchase requirements or choose to purchase such vehicles in the future, they remain free
to do so. Commenters provided no reason to believe that these voluntary purchase
agreements were entered into to facilitate compliance with the GHG emission standards,
and we are not aware of any reason that States, municipalities, or businesses not subject
to the standards {i.e., not manufacturers or suppliers) would be involved in the design or
production of compliant vehicles or engines. To the extent commenters meant to assert
that the purchases were intended to satisfy local emission-reduction targets, many such
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targets are voluntary, and nothing in this final action prevents entities from proceeding with
or adjusting existing strategies.
Regarding warranty, after considering comments that the warranty provisions for batteries
are not limited to GHG emissions and continue to apply under the EPA criteria pollutant
programs, which are out of scope of this rulemaking, the existing regulations' warranty
coverage for batteries used in EVs remain in place (see section VII of the preamble to this
final action). Specifically, the Agency is not takingfinal action at this time on the proposal
to remove batteries for light- and medium-duty EVs and plug-in hybrid EVs from the list of
specified major emission control components in 40 CFR 85.2103(d)(1). Similarly, emission-
related warranty would continue to apply for fuel cell stacks, batteries, and other
components used with heavy-duty battery EVs and fuel cell EVs under 40 CFR 1037.120(c).
The EPA is removing, as proposed, the battery durability requirements and durability
monitoring requirements for light-, medium-, and heavy-duty vehicles but notes that the
international regulations on which the Agency based its durability provisions remain
available for manufacturers to voluntarily adopt for their EVs.3 With respect to past
purchases, the battery warranty and in-use performance requirements cited by
commenters are not setto begin until MY2027. Forthis reason, purchasers cannot
reasonably have relied on these requirements for past purchases, and any battery
warranties or performance guarantees were entered into on a voluntary basis separately
from these regulatory requirements.
The benefits and costs related to consumer fuel costs are provided within the RIA forthis
final action. Additionally, consumers who wish to purchase EVs or other vehicles are not
prohibited from purchasing those vehicles, nor does the EPA believe that those vehicles
will not exist for consumers to choose. Finally, future gasoline prices are difficult to predict,
especially related to individual regulatory actions, given the complexity of the relevant
global markets that influence such prices.
Lastly, the EPA believes that where individual Americans choose to live and the factors that
go into that decision, such as insurance prices or susceptibility to sea level rise, are not
reliance interests attributable to this rulemaking. Multiple factors impact where a person
may choose to live and how much insurance may cost at that location beyond whether the
EPA has authority to regulate GHG emissions from new motor vehicles and engines.
3 UN Economic Commission for Europe (UNECE).ECE/TRANS/180/Add.22, Addendum 22: United Nations
Global Technical Regulation, No.22, United Nations Global Technical Regulation on In-vehicle Battery
Durability for Electrified Vehicles; Adopted April 14, 2022.
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1.3.3.5 Electric Vehicle Supply Chain
EPA Summary of Comments
One commenter stated that since 2020, its members in the EV, battery, and critical mineral
and materials sectors have announced over $55 billion in private sector investments that
are projected to yield nearly 70,000 direct jobs. Accordingto the commenter, its members
have built EV factories, battery factories, and charging networks across the U.S. and have
invested heavily in the mining sector and in new refrigerant systems.
Commenters stated that at-risk investments total at least $156 billion with the highest
exposure ($140 billion) in battery technology and supply chain, EV assembly, and
components. According to the commenter, these investments represent 160,000 American
jobs, including 146,000 high-quality skilled positions and the Southeast region (Georgia,
Alabama, Florida, Tennessee, and the Carolinas) faces the greatest impact from potential
lost investments and jobs. The commenter further asserted that companies have planned
their technology pathways, investments, and production based on the existing regulatory
framework extending through 2030 and beyond. Commenters also stated that companies
have retooled factories and developed new supply chains to meet stricter GHG emission
standards.
Commenters also stated that the EPA's current proposal is reasonably expected to reduce
the manufacture and sale of EVs nationwide, which would negatively impact the expected
utilization of charging networks and therefore the associated adverse impacts on charging
network-derived earnings.
Commenters also stated that as far back as the 2020 standards rule, global automakers
expressed concern with an abrupt halt to gradual fuel economy improvements, which
could result in stranded capital investments for automakers and suppliers. Commenters
stated that the 2020 rule explained that "the idea behind stranded capital is that
manufacturers amortize research, development, and tooling expenses over many years,
especially for engines and transmissions" and noted that it was usual to take the potential
for stranded capital into account in standard-setting. According to the commenter, the
2020 rule contained extensive discussion of the potential for stranded capital costs and
how the EPA was taking it into account in making its standards less stringent. The
commenter asserted that the EPA's cost-benefit analysis is unreliable and the proposal is
arbitrary and capricious because stranded capital is not included in the cost-
benefit analysis.
EPA Response
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As discussed in section IV.A.2 of the final action preamble, reliance interests are irrelevant
when assessing whether to rescind an action that the Agency lacked statutory authority to
take because no amount of reliance could justify continuing a program that allows the
Agency to wield power that neither Congress nor the Constitution has conferred. Given the
conclusions reached in this final action, retaining the program for any additional period, or
finalizing what would amount to the promulgation of revised regulations that include a
ramp down or phase out, would exceed the Agency's statutory authority. The EPA is not
aware of, and commenters did not identify, any statutory authority or settled legal principle
that would authorize the Agency to finalize such actions absent statutory authority under
CAA section 202(a)(1).
As discussed in the final action preamble, the EPA acknowledges that certain regulated
parties, and thus corresponding parties in the supply chain for such regulated parties, have
invested significantly in EV production and technologies that have been or could be used to
comply with the GHG emission standards. Nothing in this final action precludes market
participants from continuing to make such investments or removes any benefit capable of
engendering cognizable reliance interests. Nor are such investments by nonregulated
parties capable of expanding the EPA's statutory authority under CAA section 202(a)(1). In
general, the EPA concludes that investments in the supply chain in EVs and related
technologies should not be attributed exclusively, or even substantially, to the EPA's GHG
emissions standards. The new motor vehicle and engine market and related supply chains
are complex and informed by a wide variety of economic and regulatory considerations.
Investments in the supply chain that relate to compliance with existing regulations would
not be impacted by this regulation. With respect to economic influences, we note that EV
demand has been subject to significant fluctuation and declines unrelated to this
rulemaking. The decline in demand is attributable in part to Congress, which recently
repealed certain tax credits and subsidies for EVs and disapproved three prior EPA
preemption waivers for EV-forcing California vehicle and engine regulations. Changes in
consumer preferences are also relevant factors. The ability of market participants to earn a
return on EV and related investments thus turns on a variety of factors that ultimately fall
outside the Agency's regulatory wheelhouse. The CAA requires us to take cost into account
in various ways, but it does not require the EPA to ensure that EV investments turn a profit.
The EPA disagrees that possible challenges facing automakers in complying with
international emission standards are legitimate reliance interests that counsel against the
rescission and repeals, as addressed in the final action preamble. We question the premise
that automakers assume their products will comply with applicable emission standards in
export markets, as GHG emission standards are not in place for new vehicles and engines
(or the same classes of new vehicles and engines) in all export markets and vary
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significantly among nations where such GHG emission standards are in place and
applicable to imports. We also note that many automakers structure design, marketing,
and production strategies to account for differing emission standards across various
markets, both for GHG emissions and for emissions of criteria pollutants and air toxics.
Regardless, as discussed above, nothing in this final action prevents regulated parties from
maintaining current plans to the extent that they believe doing so is a convenient way to
more easily participate in export markets.
Contrary to the commenters' suggestion that the alleged reliance interests warrant a
limited repeal of the 2024 GHG emission standards vehicle rule instead of rescinding the
Endangerment Finding, the EPA has no discretion to do so, as discussed in the final action
preamble and elsewhere in this document.
2 Rescission of the Endangerment Finding
2.1 Primary Rationale for Rescission
2.1.1 Best Reading of CAA Section 202(a)
2.1.1.1 Air Pollution
EPA Summary of Comments
Many commenters supported the EPA's proposed reading of the term "air pollution" and its
function within CAA section 202(a)(1). These commenters agreed with all or some of the
Agency's proposed rationales and evidence in support of these conclusions, with some
offering additional regulatory history, legislative history, or interpretive arguments that
further supported these conclusions.
Conversely, adverse commenters stated that the proposed addition of "through local or
regional exposure" has no basis in the statutory text. Commenters stated that it would be a
strange understanding of the settled rules of statutory interpretation if an agency simply
added new words to a statute that Congress had not put there - particularly in the wake of
the Supreme Court's decision in Loper Bright.
Commenters stated that the EPA is trying to draw an extremely fine distinction between
various impacts to say one set is covered but another set is not. For example, commenters
asserted that GHGs, through their interactions with infrared radiation, change the
environment and thus cause negative effects on both health and welfare. Commenters
stated that the EPA is taking the position that only interactions with molecules can make
something an air pollutant and that interaction in the environment with energy does not
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count. Commenters argued that, if so, the EPA should point to some legislative language or
legislative text to support that position.
Commenters further claimed that Congress could easily have added those five words -
"through local or regional exposure" - had it intended such a limiting construction of CAA
section 202(a)(1). Commenters argued that Congress did just that in other sections of the
CAA, including CAA language in the visibility protection program, discussing the "interstate
transport of air pollutants" between States, and CAA language establishing the Ozone
Transport Region and CAA sections 109(a) and (b).
Commenters also asserted that Congress specifically authorized the EPA to control
emissions of "moving sources" and broadened the power of the EPA to regulate motor
vehicle emissions even more through the 1960s revisions to the CAA. One commenter
cited to Train v. NRDC, 421 U.S. 60 (1975), as stating that Congress directed the Surgeon
General to focus his attention on the health hazards resulting from motor vehicle
emissions and recounting the statutory history noted above.
EPA Response
The EPA is finalizing that the best reading of CAA section 202(a)(1), informed by the ordinary
meaning of the term "air pollution" at the time of enactment, as well as context, structure,
and history, is that the Agency's authority to prescribe emission standards relates to
pollution that adversely impacts health and welfare through local and regional exposure.
The CAA has never included a definition of "air pollution," which is a term central to the
scope of the EPA's authority under CAA section 202(a)(1) and to the regulatory object of the
provision -"air pollution which may reasonably be anticipated to endanger public health or
welfare." The "single, best meaning" of the term "air pollution" is '"fixed at the time of
enactment'" and informed by "applying all relevant interpretive tools." Loper Bright, 603
U.S. at 400 (quoting Wis. Cent. Ltd. v. United States, 585 U.S. 274, 284 (2018)).
The EPA disagrees with commenters' assertion that the Agency is adding words to the
statute. Rather, the best reading is informed by the meaning of the statutory term "air
pollution" set when Congress enacted the language that became CAA section 202(a)(1) in
1965, Pub. L. No. 89-272, section 101 (8), 79 Stat. 992, and incorporated that language, with
revisions, into Title II of the CAAin 1970, Pub. L. No. 91-604, section 6(a), 84 Stat. 1690.The
ordinary meaning of the term, reinforced by context, structure, and unbroken regulatory
history through 2009, is that "air pollution" as used in CAA section 202(a)(1) refers to
phenomena that adversely impact public health and welfare through local or regional
exposure, such that the EPA's authority to prescribe emission standards relates to
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emissions that cause or contribute to air pollution that may reasonably be anticipated to
endanger public health or welfare through local or regional exposure.
In section V.A of the final action preamble, the EPA details the contextual and structural
indicators that form the basis for this reading of the term "air pollution" and its operation
within CAA section 202(a)(1). This includes a review of named air pollutants throughout
CAA section 202 and elsewhere in the CAA, including the criteria pollutant provisions
added to CAA section 202(b) alongside enactment of CAA section 202(a)(1) in 1970, all of
which adversely impact public health and welfare through local or regional exposure. The
EPA is also relying on dictionary definitions of the term "air pollution," as well as uses in
close-in-time judicial decisions and legislative history, that build out the term's ordinary
meaning. See Perrin v. United States, 444 U.S. 37, 42 (1979) ("[u]nless otherwise defined,
words will be interpreted as taking their ordinary, contemporary, common meaning"); EPA
v. CalumetShreveport Retin., L.L.C., 605 U.S. 627, 638 (2025) (interpreting undefined terms
in CAA section 307 according to their contemporary, ordinary meaning). Finally, the EPA is
reading the term "air pollution" in context with the other terms used in CAA section
202(a)(1) and the applicable statutory definitions of "air pollutant" and "welfare," as well as
giving appropriate weight to the Agency's longstanding practice prior to 2009 that more
faithfully adhered to the best reading of the statute from the time of enactment onward.
Under ordinary principles of statutory interpretation, these indicia, individually and
collectively, support the conclusion that "air pollution" is best read as pollution that
adversely impacts public health and welfare through local and regional exposure.
Commenters do not point to contrary textual or structural evidence that persuasively
supports interpreting "air pollution" to mean any phenomenon as defined by the
Administrator. Notably, the statute does not authorize the Administrator to define "air
pollution" or any of the other terms in CAA section 202(a)(1). When Congress intends to
confer the authority to define terms, it knows how to do so, and indeed has done so in other
provisions of the CAA and environmental statutes. See, e.g., 42 U.S.C. § 7410(m)
(authorizing the Administrator to define "plan or plan item" for purposes of applying certain
sanctions in the SIP context for NAAQS implementation), 7411 (i) (authorizing the
Administrator to define the term "country elevators" in the stationary source context); 33
U.S.C. § 1311 (b)(1 )(A) (Clean Water Act provision requiring "the application of the best
practicable control technology currently available as defined by the Administrator").
Instead, CAA section 202(a)(1) authorizes the Administrator to prescribe standards for a
class or classes of new motor vehicle engines that, in his "judgment," emit any air pollutant
that causes, or contributes to, air pollution which may reasonably be anticipated to
endanger public health or welfare. The exercise of that "judgment" is constrained by the
statutory language, including the ordinary meaning of the term "air pollution," informed, as
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explained above and in the final action preamble, by context, history, structure, and
longstanding practice.
Indeed, commenters seem to acknowledge a critical distinction between air pollution with
adverse impacts from local or regional exposure and global climate change effects.
Pollutants like criteria pollutants and air toxics harm health and welfare directly, whether
through contact with the human body and the environment or by combining with other
agents to cause such health or welfare harms. GHGs are different; the Endangerment
Finding itself recognized that the six "well-mixed" GHGs involved a "unique" and indirect
causal chain, that none of the health effects were associated "with direct exposure to
[GHGs]," 74 FR 66527, that many of the identified welfare impacts could also be
considered health impacts, and that all such impacts reflected the same multi-stage
causal pathways, 74 FR 66528-29, 66531, 66534. Rather, global concentrations of GHGs,
including emissions from at least the start of the industrial age, current emissions, and
projected future emissions, were found to play a role in global environmental shifts that
play a role in local or regional adverse impacts.
In addition to being inconsistent with the ordinary meaning of "air pollution" as that term
was enacted in 1965 and retained in the 1970 CAA, this causal chain is not consistent with
the additional causal language Congress added to the statute in the 1977 CAA
Amendments - that the "air pollution" may "reasonably be anticipated to" endanger. As
discussed in section V.A of the final action preamble, this language reflects ordinary
principles of proximate cause and tracks nearly verbatim the ordinary meaning of
"foreseeability." Congress used a phrase that both clarified the "air pollution" need not
already be endangering public health or welfare and, at the same time, placed an outer
bounds on the acceptable causal chain. The Agency has significant flexibility to tackle air
pollution that threatens public health or welfare at the level of regional and local exposure,
but that flexibility does not extend to the determination, made in the Endangerment
Finding, that global climate change concerns must be tackled by the international
community such that all nations and all potential sources "must do their part" to avoid a
collective action problem. 74 FR 66543. The causal chain required to connect "air
pollution" (defined as the six "well-mixed" GHGs) to endangerment necessarily takes a
circuitous route because the "air pollution" as defined does not harm humans or the
environment through direct exposure. Rather, the "air pollution" as defined requires inputs
past, present, and future from all domestic and international anthropogenic emission
sources that, collectively as global concentrations, lead the planet to retain additional
energy from solar radiation, which leads in turn to increased temperature, which leads in
turn to what the Endangerment Finding identified as "multiple pathways" of potential harm
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that interact with one another and with unrelated forces (for example, changes in
agricultural production).
The EPA further disagrees that separate sections of the CAAwith their own text, structure,
and history require the Agency to retain the interpretation of CAA section 202(a)(1) adopted
in the Endangerment Finding. Indeed, the provisions cited by commenters support the
interpretation finalized in this action by suggesting that when Congress intended the CAA to
authorize EPA regulatory action in response to interstate or international emissions, it
provided such authority expressly by amending the statute. No such language appears in
CAA section 202, despite multiple amendments to the provision over time to add
additional instructions to regulate criteria pollutants and air toxics from particular classes
of new motorvehicles in particular ways.
For example, CAA' provisions governing interstate transport and those within the visibility
protection program do not support commenters' arguments. Pollutants regulated under
these programs include sulfur dioxide (S02), NOx, and PM, all of which comprise air
pollution with local and regional impacts. The mere fact that emissions may travel across
state lines to adversely impact public health and welfare in localities and regions distant
from their point of origin does not present an example at odds with the EPA's analysis why
GHGs are not encompassed within CAA section 202(a)(1). No matter where such
emissions travel, the impacts occur through local or regional exposure, consistent with the
ordinary meaning of "air pollution" and ordinary causation principles. That includes, for
example, ozone, which forms and adversely impacts health and welfare at the regional and
local level by the interaction of pollutants, regardless whether the precursor pollutants are
emitted there or travel from elsewhere. Similarly, regardless whether PM air pollution in a
given State results almost exclusively from source emissions in that State or results in
significant part from PM emissions in another country that travels a significant distance,
the regulatory object of the statute is the regional and local impact.
CAA section 184, establishing the Ozone Transport Region, does not support the position
summarized above, either. The authorizing statutory language is evidence that when
Congress intends to address interstate transport of emissions, let alone international
emissions, it does so expressly. Similar adverse comments based on the CAA's other
interstate or international transport provisions, CAA section 179B (regarding
demonstrations with respect to international emissions), and CAA section 115 (authorizing
the Administrator to require States to control emissions with international impacts if the
impacted nation has reciprocal provisions in place, among other things), all sufferfrom the
same defect. Each reinforces the conclusion that Congress takes an express rather than
implied approach to addressing air quality problems that are caused in part by interstate or
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international emissions. Co mm enters do not explain why these provisions, which have
historically been applied to criteria pollutants and others that fall squarely within air
pollution with local and regional impacts or (as with ozone transport) expressly apply only
to a criteria pollutant, stand for the proposition that CAA section 202(a)(1) authorizes the
regulation of GHGs given the differences discussed in the final action preamble and this
document.
The EPA disagrees with commenters' argument that NAAQS provisions are an example of
Congress limiting the EPA's authority to "air pollution with regional or local
impacts." Commenters point to the use of "ambient air" in CAA sections 108 and 109 as
limiting the EPA's authority, arguing that the absence of such language in CAA section
202(a)(1) is telling. However, CAA section 202(a)(1) begins by stating that the standards
authorized apply to "the emission of any air pollutant." "Air pollutant," in turn, is defined in
part as any air pollutant that "enters the ambient air." Therefore, the limitation commenter
cites in the NAAQS provisions is incorporated into CAA section 202(a)(1) as well and does
not support the argument. Consistent with this understanding of sections 108 and 109, the
EPA has not regulated GHGs as criteria pollutants within the NAAQS.
Citations to CAA section 109 are similarly inapt. CAA section 109(a) instructs the EPA to
develop primary and secondary NAAQS that provide the requisite protection of public
health and welfare, respectively. Commenters focus in isolation on CAA section 109(b)(2),
which sets out what level of protection the EPA must provide for secondary NAAQS
informed by welfare effects separately from CAA section 109(b)(1), which sets out what
level of protection the EPA must provide for primary NAAQS informed by health effects.
Whereas CAA section 202(a)(1) refers, like CAA section 108(a), to "health or welfare"
together, the separate NAAQS provisions in CAA section 109(b)(1) and 109(b)(2) provide
different standards that the NAAQS must achieve for health impacts (protection with an
adequate margin of safety) and for welfare impacts (protection, with no reference to an
adequate margin of safety). At bottom, CAA section 109(b)(2) is not comparable to CAA
section 202(a)(1) because it addresses the level of protection the EPA must achieve in
setting secondary NAAQS, rather than the scope of the Agency's authority to identify and
regulate emissions that cause or contribute to air pollution which may reasonably be
anticipated to endanger public health or welfare.
The EPA further disagrees with a commenter's assertion that Train v. NRDC, 421 U.S. 60
(1975), is relevant to this rule. First, the EPA is not asserting that it lacks authority to
regulate motor vehicle emissions, as the commenter seems to suggest. Second, Train
addressed the EPA's authority to approve a SIP for stationary sources that included a
variance procedure. The case did not address the EPA's authority regarding motor vehicles,
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and the statements commenter cites appear only in the background section of the
decision. The discussion briefly summarizes history at a high level, including that Congress
initially limited Federal involvement to non-regulatory actions by the Surgeon General and
then, in 1965, "broadened federal authority to control motorvehicle emissions and to make
grants to state pollution control agencies." Id. at 64. The remainder of the discussion then
shifts to the NAAQS program and stationary sources, and in particular the division of
responsibility between States and the EPA. Id. at 65-67.
EPA Summary of Comments
Several commenters stated that the EPA's proposed interpretation of "air pollution" (which
some commenters framed as "air pollutants") is inconsistent with the definition of
"welfare" in CAA section 302(h). Commenters stated that the proposal recognizes that
"welfare" is "defined broadly" in the CAA, but omits mention of the inclusion of "climate"
impacts. According to commenters, these are not harms typically caused by direct
exposure, but rather through other pathways with multiple links. These commenters stated
that the requirement established by the statute - that the Administrator regulate air
pollutants with harmful impacts on public health or welfare, including impacts on climate -
is broad and expresses no limitations on the word "climate" as incorporated through the
statutory definition of "welfare." These commenters argued that this situation falls within
the Supreme Court's prior statements in other statutory contexts that "when Congress
chooses not to include any exceptions to a broad rule, courts [must] apply the broad rule."
Bostockv. Clayton Cnty., 590 U.S. 644, 669 (2020).
Commenters stated that the EPA argues that the mechanism of the harm of "air pollution"
or "air pollutants" (different commenters used different terminology) must be the same as
those of the other pollutants already regulated, and asserted that there are major problems
with this reading. Commenters asserted that this reading functionally rewrites the statute
from "public health or welfare" to just "public health" because, in their view, none of the
welfare impacts listed in the welfare definition at CAA section 302(h) are caused by either
inhalation or dermal contact and most are not direct impacts on human beings.
Commenters stated that, more to the point, impacts on "weather" and "climate," terms
that appear in the CAA section 302(h) definition, are not based on a person inhaling or
touching any pollutant. On this basis, commenters argued that the EPA is rewriting the CAA
to remove clear statutory text and therefore cannot meet the Loper Bright test of best
statutory interpretation.
Commenters emphasized that Congress affirmatively added climate to the list of "effects
on welfare" in the 1970 CAA and cited legislative history to characterize that addition. For
example, commenters stated that Congress had recently been made aware of the threat of
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climate change by President Lyndon B. Johnson, and that members of the House and
Senate echoed these concerns in floor statements and in articles and speeches they
introduced into the Congressional Record.
Commenters stated that paired with a reading of the plain text, this historical evidence
shows that the enumeration of "weather" and "climate" in CAA section 302(h) is best read
to include impacts on global climate. Commenters argued that the EPA inadequately
engaged with the plain text of CAA section 302(h) and/or the plain text of CAA section
202(a)(1) in relevant part. In support, commenters stated that statutory drafting history,
testimony before the key legislative committee, scientific reports, and Executive Branch
documents all referred to "climate" in its global dimension and that some of these
materials referenced carbon dioxide (C02) emissions as air pollution. Commenters argued
that this evidence rebuts both the EPA's proposed restriction on regulation of "GHG
emissions based on global climate change concerns" and its proposed "local or regional
exposure" limit on air pollution harms.
Several of these commenters emphasized that the Supreme Court explicitly cited this
provision in Massachusetts to support the conclusion that Congress intended the CAA to
address pollutants with effects other than immediate, local ones. 549 U.S. at 506. Some
also cited to Justice Breyer's separate opinion in UARG, 573 U.S. at 343 (Breyer, J.,
concurring in part), and academic articles referencing legislative history and the statutory
definition of welfare. Some further stated that in defining "welfare," Congress incorporated
language inclusive of long-range atmospheric processes, including the "transformation,"
"conversion," or "combination" of air pollutants. According to commenters, it was widely
known at the time of enactment that these processes occur in the atmosphere well beyond
local or regional scales, indicating congressional drafters intended the Administrator to
consider impacts to public health and welfare beyond local or regional scales.
EPA Response
The EPA disagrees with commenters' arguments rooted in the definition of "welfare" in CAA
section 302(h), which misapplies the statute and misconstrues terms included in the
definition in multiple respects. Properly understood, as discussed in section V.A of the final
action preamble, this provision reinforces our conclusion that the 2009 Endangerment
Finding and resulting GHG emission standards for new motor vehicles and engines are
inconsistent with the best reading of the statute.
Congress added the word "climate" to a more limited, pre-existing version of the CAA
section 302 definition of "welfare" in 1970. See Pub. L. 91-604, 84 Stat. 1676,1710. The
version as of 1970 is essentially the current definition, but without the final clause referring
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to conversion - "whether caused by transformation, conversion, or combination with other
air pollutants" - which was added as part of the 1990 CAA Amendments' overhaul of
stationary source regulation. See Pub. L. 101 -549,104 Stat. 2399, 2470. Notably, several
commenters appear to misattribute the later additional of "transformation," "conversion,"
and "combination" language to the 1970 definition rather than the 1990 CAA Amendments,
an important oversight given the context of the 1990 CAA Amendments.
Dictionary definitions of "climate" contemporaneous with the term's 1970 addition to the
CAA make clear that the ordinary meaning of the term referred to local and regional, rather
than worldwide, conditions. See, e.g., Climate, Am. Heritage Dictionary 136 (1970) ("[t]he
prevailing weather in a particular region" or "[a] region manifesting particular
meteorological conditions") (emphases added). This definition is consistent with
contemporary uses of the term in judicial decisions, and it makes clear that the climate
concept within the CAA is fundamentally regional. The ordinary meaning of "climate" as of
1970 is distinct from the global climate change concepts used in the 2009 Endangerment
Finding and would require the addition of "global" or another modifier to reach that scope.
Indeed, when Congress intended the EPA to consider GHG emissions in the sense of global
climate change concerns with respect to renewable fuels in the RFS program, it used the
different term "climate change." 42 U.S.C. § 7545(o)(2)(B)(ii)(l) (emphasis added); Pub. L.
110-140, section 202,121 Stat. 1521 (2007) (adding this provision).
To the extent commenters are suggesting or relying on understandings of the word
"climate" as of 2026, this does not affect the best reading of the statute fixed at the time of
enactment. See Loper Bright, 603 U.S. at 400. Regardless, modern dictionaries continue to
define the term "climate" in isolation as "a region of the earth having specified climactic
conditions." Merriam-Webster.com. 2026. https://www.merriam-
webster.com/dictionary/climate: see also Climate, Am. Heritage Dictionary (5th ed. 2022)
(retainingthe definition presented inthe 1970 edition). Nor do commenters appearto be
suggesting that the ordinary meaning of the term had changed by the 1990 CAA
Amendments when Congress added the final clause of the welfare definition without
disturbing "climate" or the surrounding terms. Certainly in 1970 and 1990, and even today
despite greater penetration of global climate change terminology into the lexicon, an
ordinary person would understand the word "climate" to mean local or regional conditions.
That supports our conclusions that the air pollution of concern under CAA section
202(a)(1) is local or regional exposure that harms health or welfare, and that the
Endangerment Finding departed from the best reading of the statute when it asserted
authority to regulate, including by finding risk to "climate" only through an attenuated and
indirect causal chain involving no direct interaction between "climate" and GHGs
themselves. The Administrator in 2009 did not find that concentrations of the six "well-
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mixed" GHGs in a particular locale - one State or region, e.g. - would harm climate in that
locale. Rather, the Administrator found endangerment byjumpingto worldwide emissions
and worldwide concentrations that influenced other phenomena that, in turn, were
projected to harm such climates
Ordinary principles of statutory interpretation further support the EPA's reading. It is a well-
established principle that statutory terms must be read in their broader statutory context
See Institutional S'holderServs. v. SEC, 142 F. 4th 757, 767 (D.C. Cir. 2025) (rejecting
agency interpretation of the undefined term "solicit" after looking to statutory structure and
context to reinforce contemporary dictionary definitions). And "[bjoth the ejusdem and the
noscitur canon apply when the term in question is directly preceded by a list of terms."
Overdevest Nurseries, LP. v. Walsh, 2 F.4th 977, 983 (D.C. Cir. 2021) (citations omitted).
"Climate" appears in a list of terms linked to the phrase "effects on. " Everything else in that
list (soils, water, crops, vegetation, manmade materials, animals, wildlife, weather, and
visibility) exists in particular places - localities and regions - and are evaluated in that
context even if particular instantiations of those terms may exist in multiple locales or
regions {i.e., crops planted in California and the Midwest). Congress said "soils," not
"national agricultural production." Crops, vegetation, manmade materials, animals,
wildlife, weather, and visibility are also things that vary locally and regionally. And the
"effects on" list appears together with "damage to and deterioration of property, and
hazards to transportation" and "effects on economic values and on personal comfort and
well-being." These are also phenomena that experience impacts at a local or regional level,
in particular places. An individual experiences personal comfort and well-being where they
live and work; global concentrations of GHGs do not endanger those values directly, and
the Endangerment Finding did not claim any such direct pathway. Rather, the
Endangerment Findingfound that GHG emissions contributed to global GHG
concentrations that influenced phenomena that, in turn, lead to impacts that may impact
comfort and well-being. One could imagine a statute where Congress provided that
"welfare" includes "effects on" international values (temperature, sea level, etc). Congress
did not do that here, even when last amending this statutory provision in 1990.
The entire "effects on" list appears together with "damage to and deterioration of property,
and hazards to transportation" and "effects on economic values and on personal comfort
and well-being." These are also things that happen through local and regional exposure.
One could imagine a statute where Congress provided that "welfare" includes "effects on"
national or even internationalvalues (agriculture, temperature, sea level, etc). Congress
did not do that here, even when last amending this statutory provision in 1990.
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The addition of "whether caused by transformation, conversion, or combination with other
air pollutants" to the definition of welfare in the 1990 CAA Amendments also supports our
view. Pub. L. 101 -549, section 109, 104 Stat. 2399, 2470 (1990). That clause modifies the
"effects on" list," "damage to and deterioration of property, and hazards to transportation,"
and "effects on economic values and on personal comfort and well-being." That is the
controlling language; the "whether caused by" clarifies that emitted pollutants themselves
may cause such impacts or may combine with other pollutants to cause such impacts {i.e.,
ozone formation). Congress chose the words "caused by," rather than contribute or any
other phrasing that broadens the causal chain. That is relevant because the causal
relationship in this definition is more restrictive than that in CAA section 202(a)(1).
Certainly, it cannot be read to broaden the causal relationship required by CAA section
202(a)(1).
More generally, Congress made this change in the same title of the 1990 CAA Amendments
that added various means to combat criteria pollutants that form from the emission of
various pollutants on a local and regional basis. Pub. L. 101-549, Title 1,104 Stat. 2399,
2399-2471 (1990) ("Title I - Provisions for Attainment and Maintenance of National Ambient
Air Quality Standards"). The most plausible understanding is that Congress sought to
clarify that pollutants and pollution formed by the interaction of precursors, e.g., ozone, is
relevant to welfare, and that the pollutant emissions that form ozone are therefore
encompassed as well.
The EPA disagrees with commenters' assertions that the proposal functionally omits the
term "welfare" by requiring that the mechanism of the harm of "air pollutants" must be the
same as those of other pollutants already regulated. The Agency is not arguing that the
mechanism of harm for all forms of air pollution is or must be identical; rather, we observe
that what all regulated pollutants (other than GHGs regulated in response to global climate
change concerns) have in common is causing or contributing to air pollution that adversely
impacts public health or welfare by local and regional exposure. Either the pollutants
themselves harm humans and/or the environment (e.g., hazardous air pollutants (HAPs),
PM) or they form pollution that harms humans and/or the environment (e.g., NOx as a
precursor to ozone). For example, certain air toxics impact wildlife and vegetation by
destroying tissue on contact, while ozone, for example, harms welfare by entering into the
tissue of sensitive plants, thereby reducing photosynthesis, slowing growth, and increasing
sensitivity to damage and disease. The Endangerment Finding utilized an entirely differently
theory that is inconsistent with such understandings of welfare and used an unsustainably
long and speculative causal chain. Under this theory, it is not exposure to GHG emissions,
whether individually or in combination, that endangers welfare - indeed, plant life, a core
element of many of the terms used in the definition of welfare, must come into contact with
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C02 to survive. Rather, the Endangerment Finding identified dangers to welfare by
concludingthat GHG emissions contributed to worldwide GHG concentrations that would
elevate over time, thereby exerting a greater effect on GMST, thereby playing a causal role in
additional phenomena with multiple inputs that may, in turn, harm welfare. See 74 FR
66528-31 (arguing that many of the identified "welfare" effects could be considered
"health" effects and that both involves the same causal "pathways").
Other arguments from commenters that the EPA is reading "welfare" out of the statute also
fail. Welfare impacts are relevant and properly understood as arising from air pollution that
harms from its presence in the air. Wildlife and vegetation are harmed through dermal {i.e.,
physical) exposure and inhalation. "Weather, visibility, and climate" are also regional and
local phenomena. See above for a discussion of how this is also true for climate. As to
weather, Congress had in mind phenomena like acid rain and smog. See Coalition for
Responsible Regulation, Inc. v. EPA, 2012 U.S. App. LEXIS 25997, *40 (Brown, J., dissenting
from denial of rh'g en banc) ("[W]eather and climate issues targeted by the CAA involve
direct, deleterious, localized effects caused by polluted air people breathe or suspended
pollutants that may be deposited on land and crops by precipitation.") Visibility follows the
same pattern as climate and weather. Dictionary definitions confirm that the Congress of
the 1970 CAA Amendments would have understood weather as more direct and localized.
Weather is "[t]he state of the atmosphere at a given time and place, described by
temperature, moisture, wind velocity, and pressure." Am. Heritage Dictionary 785 (1970)
(emphasis added).
The EPA's proposal also illustrates how the 2009 Endangerment Finding erred by
interpreting "welfare" to include effects like global temperature change, sea level rise, and
ocean acidification. None of those effects fit well into the single, best readings of
"weather," "visibility," or "climate."
Further emphasis on the effect of "whether caused by" is also important to supporting the
EPA's conclusions. As noted above, Congress used more restrictive causal terminology
here than even in CAA section 202(a)(1). Critically, the Endangerment Finding did not find
that elevated concentrations of GHGs cause adverse welfare impacts. Rather, it found that
they contributed to phenomena that in turn contributed to such impacts at the local level.
In other words, elevated GHG concentrations (not just from new motor vehicles and
engines but from all anthropogenic sources) contribute to increased temperatures, which
contributes to melting ice and different global climate pattern changes, which then
contribute to local or regional weather and climate changes. The pollutants/pollution are
not directly causing the local or regional welfare impacts.
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Commenters' references to isolated statements about the threat of climate change during
debate over the 1970 CAA do not undercut the EPA's best reading. See further discussion in
section V.A.1 of the final rule preamble.
As explained in section V.A and V.B of the final action preamble and elsewhere in this
document, including section 2.1.2.1.3, Congress has repeatedly considered and rejected
proposals that would have authorized the EPA to prescribe emission standards for GHGs.
Whether certain staff were aware of reports suggesting that C02 emissions could lead to
global climate change is not relevant - the question here is whether Congress as a whole
wrote it into the CAA. The best reading of the statute indicates that Congress did not do so,
and indeed, the legislative history makes clear that Congress believed it was legislating in
response to criteria pollutants at the heart of the acute air pollution problems at issue in
the 1960s and 1970s. Commenters' assertions about legislative history are not supported
by the legislative record and, in any event, cannot overcome the statutory text. Isolated
statements by individual legislators, let alone statements by witnesses in committee
hearings, are not probative of the statute's meaning. NLRB v. SI/1/Gen., Inc., 580 U.S. 288,
307 (2017) ("[F]loor statements by individual legislators rank among the least illuminating
forms of legislative history"). And while "clear evidence of congressional intent may
illuminate ambiguous text[, w]e will not take the opposite tack of allowing ambiguous
legislative history to muddy clear statutory language." Milnerv. Dep'tofthe Navy, 562 U.S.
562,572 (2011).
The EPA disagrees with commenters who argued that the Supreme Court's decision in
Bostock supports the contention that the statute must be read broadly enough to
encompass global climate change concerns, whether as a general matter or specifically
because of the inclusion of the defined term "welfare." There, the Court emphasized
repeatedly that undefined statutory terms must be read in accordance with ordinary
meaning at the time of enactment and used relevant dictionary definitions and precedent
to interpret the terms "sex," "because of," and "discriminate" to determine whether Title VII
of the Civil Rights Act imposed liability for workplace discrimination based on sexual
orientation and gender identity. 590 U.S. at 655-58; see id. at 659 ("From the ordinary
public meaning of the statute's language at the time of the law's adoption, a
straightforward rule emerges."). The primary passage cited by commenters is the Court's
response to an argument by the employers that the absence of sexual orientation and
gender identity from the statute's list of protected classes indicated such discrimination
was not covered. The Court rejected this argument, reasoning that "discrimination based
on homosexuality or transgender status necessarily entails discrimination based on sex," a
listed characteristic, and that "Congress's failure to speak directly to a specific case that
falls within a more general statutory rule [does not] creat[e] a tacit exception." Id. at 669.
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The best reading of the statute reflected in the Agency's final action is supported, not
undermined, by the interpretive principles in Bostock. Whereas commenters decline or
refuse to engage with the ordinary meaning of "air pollution" and instead place decisive
weight on the definition of "welfare," and individual terms within that definition for which
they also refuse to apply ordinary, contemporary meaning, the EPA is thoroughly analyzing
the ordinary, contemporary meaning of each term and reading them together in context.
The precise holding in Bostock, a conscientiously text-specific opinion, is inapposite
because the statutory language in CAA section 202(a)(1) is very different. Compare 42
U.S.C. § 2000e-2(a)(1) (unlawful to "discriminate against any individual... because of such
individual's race, color, religion, sex, or national origin"), with 42 U.S.C. § 7521 (a)(1)
("prescribe ... standards applicable to the emission of any air pollutant... which in his
judgment cause, or contribute to, air pollution which may reasonably be anticipated to
endanger public health or welfare"). There is no "broad" rule here requiring an implicit
exception. Rather, the contemporary, ordinary meaning of the term "air pollution" is the
fulcrum of the provision to which emissions must contribute and which must endanger
public health or welfare.
More generally, the EPA disagrees with commenters' attempt to characterize CAA section
202(a)(1) as one of the relatively uncommon statutes that use extraordinarily "broad
language" to confer extraordinary flexibility. Most precedents invoking this principle point to
prior cases construing the Racketeer Influenced and Corrupt Organizations Act (RICO),
which has a very broad liability provision. See Haroco, Inc. v. Am. Nat'l Bank& Tr. Co., 1A1
F.2d 384, 398 (7th Cir. 1984) ("There are some ambiguities, to be sure, but the fact that
RICO has been applied in situations not expressly anticipated by Congress does not
demonstrate ambiguity. It demonstrates breadth."). The Supreme Court has clarified that
even such broadly worded statutes do not confer limitless power or liability. Instead, the
Court has repeatedly held that such language must be understood in light of background
principles of law, such as proximate cause, against which Congress legislates when
enacting broad language. See Hemi Grp., LLC v. City of New York, 559 U.S. 1,1 (2010) ("a
plaintiff is required to show that a RICO predicate offense not only was a "but for" cause of
his injury, but was the proximate cause as well"). Therefore, even if the relatively detailed
language of CAA section 202(a)(1) in certain respects, it is best understood to limited by
proximate cause principles. And as explained in section V.C of the final action preamble
and elsewhere in this document, courts have also recognized that general language
incorporates proximate cause limitations, including in the CAA context.
EPA Summary of Comments
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Commenters stated that the proposal did not account for CAA section 202(a)(1) text and
legislative history supporting a "precautionary approach" to regulation. These commenters
stated that Congress's choice to use "endanger," as opposed to "harm," adds yet another
layer of precaution because, they assert, the term means only that someone or something
is put in a position of danger, not that such danger be actually present or measurable. See
Endangerment, Black's Law Dictionary (12th ed. 2024) (defining "endangerment" as "[t]he
act or an instance of putting someone or something in danger; exposure to peril or harm").
Commenters stated that Congress's use of the mandatory "shall," its double use of "any,"
and the additional threshold of "may reasonably be anticipated" in CAA section 202(a)(1)
further underscore that precautionary thrust. Commenters stated that Congress wanted
the EPA to err on the side of protection, not to look for ways to avoid regulation.
Commenters also stated that the 1977 CAA Amendments adopted standardized language
to emphasize the precautionary approach to be taken in "Endangerment Findings" required
in multiple provisions across the statute, including CAA section 202. Commenters stated
that, in each case, according to relevant legislative history, the intent was that the
Administrator may regulate a pollutant, emissions of which in his judgment cause or
contribute to air pollution which may reasonably be anticipated to endanger public health
or welfare. Commenters stated that a House committee report includes an extensive
discussion of the change, including statements that the change was intended to support
the views expressed by the D.C. Circuit in Ethyl Corp. v. EPA, 541 F.2d 1 (D.C. Cir. 1976) (en
banc). Commenters stated that the purposes the committee offered for the revised
language include emphasizingthe "preventive or precautionary" nature of the CAA and
assuring consideration of cumulative impacts of all sources of a pollutant.
Commenters argued more generally that this and other pertinent legislative history,
including that cited in Massachusetts, 549 U.S. at 506 n.7, confirms Congress's intent to
adopt a precautionary regulatory framework in CAA section 202.
EPA Response
The EPA does not dispute the general proposition that CAA section 202(a)(1) authorizes a
precautionary approach by using language that does not require showingthat harm is
already occurring and allows for at least some degree of uncertainty in predicted harms.
This concept and its application to the CAA have been discussed in Ethyl Corp. and
Alabama Power v. Costle, 636 F.2d 323 (D.C. Cir. 1979). The EPA agrees that these cases
inform the interpretation of CAA section 202(a)(1), including with respect to the causal
language added in the 1977 amendments subsequent to the Ethyl Corp. decision. But in
both cases, the D.C. Circuit addressed air pollution that adversely impacts public health
and welfare through local or regional exposure - lead in Ethyl Corp., and criteria pollutants
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(primarily S02 and PM) in Alabama Power. Further, the D.C. Circuit recognized that the
precautionary approach has limiting principles. See Ala. Power, 636 F.2d at 360-61
(recognizing de minimis limitations); Ethyl Corp., 541 F.2d at 18 n.32 ("even the absolute
certainty of de minimis harm might not justify government action").
The EPA disagrees, however, with commenters' conclusion that the precautionary nature of
the provision must or may be read back onto the key term "air pollution." Commenters
focused on the extent or likelihood of harm required to invoke CAA section 202(a)(1),
arguing that the EPA can act in the absence of ongoing or certain harm. However, the
absence of ongoing or certain harm is not the reason the Agency is concluding that CAA
section 202(a)(1) does not authorize regulating GHGs in response to global climate change
concerns. Rather, it is because the "air pollution" encompassed by the statutory language
is different in kind from the global climate change concerns identified in the Endangerment
Finding. In other words, the problem here is a difference in kind, not degree.
Commenters focused on the extent or likelihood of harm required to invoke CAA section
202(a)(1), arguing that the EPA can act in the absence of ongoing or certain harm. However,
the absence of ongoing or certain harm is not the reason the Agency is concluding that CAA
section 202(a)(1) does not authorize regulating GHGs in response to global climate change
concerns. Rather, it is because the "air pollution" encompassed by the statutory language
is different in kind from the global climate change concerns identified in the Endangerment
Finding. In other words, the problem here is a difference in kind, not degree.
The EPA's concerns regarding the sufficiency of the causal nexus between the GHG risks
identified in the Endangerment Finding and the scope of CAA section 202(a)(1) are related
but distinct. The ordinary meaning of "air pollution" as distinct from the global climate
change concern theory adopted in the Endangerment Findingto define "air pollution" as six
"well-mixed" GHGs reflects a distinction in causation to the extent that the ordinary
meaning of the term, fixed at the time of enactment, encompassed air pollution that
threatens public health or welfare through local or regional exposure. The threat need not
have matured into ongoing harm, and there is at least some room for uncertainty regarding
the full extent of the harms risks by the air pollution. In contrast, the Endangerment Finding
adopted a different understand in order to fit global climate change concerns within the
statute - the "air pollution," so defined, threatens public health and welfare through an
elongated chain of causation different in kind from "air pollution" as the public understood
it in the 1960s and 1970s.
As discussed in section V.A.1 of the final action preamble and elsewhere in this document,
the ordinary meaning of "reasonably be anticipated to endanger" incorporates proximate
cause principles that lend further support to this reading of "air pollution" in context.
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Whatever Congress may have had in mind when it added that language in 1977, certainly it
did not believe it was excising the relationship between "air pollution" and public health
and welfare objectives. See Ethyl Corp., 541 F.2d at 15 (holding that "regulation must be
premised on a determination of danger, a finding that'air pollution which endangers the
public health' is the end product of the emission to be regulated"); see also id. at 16
(emphasizing"the threshold determination" that "air pollution must endangerthe public
health before regulation is justified"). There is a limit to the length of the causal chain
required to establish such a relationship, and the limit Congress and the public had in mind
at the time was informed by the direct-exposure nature of familiar air-pollution harms. In
this respect as well, the Endangerment Finding went well beyond the best reading of the
statute by relying on a lengthy and attenuated chain that encompasses the global
atmosphere and virtually all significant climactic phenomena.
To note, the EPA is also finalizing in section V.A.1 of the final action preamble the separate
rationale that there must be some causal nexus between the emissions to be regulated and
the public health or welfare objectives of such regulation. The Endangerment Finding broke
with the best reading of the statute in this respect as well by severing the analysis of
contribution from the analysis of endangerment, thereby enablingthe underlying analysis
to assess one form of "air pollution" for contribution purposes and another for
endangerment purposes. That is to say, the Endangerment Finding (1) purported to satisfy
the contribution requirement using annual emissions of four GHGs by existing motor
vehicles and engines as a percentage of annual GHG emissions by all anthropogenic
sources worldwide but (2) purported to satisfy the endangerment requirement by
projecting adverse impacts from the cumulative concentration of all six "well-mixed" GHGs
in the global atmosphere from all sources over a centuries-long time horizon. This
technique also allowed the Endangerment Finding to incorporate international emissions
in an unusual way, although the CAA does not regulate international emission sources and,
in the ordinary case, an invocation of authority under CAA section 202(a)(1) would not
depend upon the existence of international emissions to identify any danger in the first
instance. For further discussion of this rationale, see section 2.1.1.3 of this document.
Commenters' reliance on the legislative history cited in Massachusetts does not support
their overall argument. The language describes Congress's efforts in 1977 to "give its
approval to the decision in Ethyl Corp v. EPA!' 549 U.S.at 506 n.7. To the extent Congress
intended CAA section 202(a)(1) to reflect that decision, it also reflects the limiting
principles acknowledged in that decision. In addition, the language of the cited legislative
history speaks in general terms and does not get to the question here, which focuses on a
difference in kind rather than a difference in degree.
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Finally, the EPA notes that during the first 40 years of this provision's history, encompassing
rulemakings for many different classes and categories of motor vehicles, the Agency
limited the scope of its regulations under CAA section 202(a)(1) to the air pollutants and air
pollution problems Congress identified in more specific provisions in CAA section 202. And
prior to 2009, the EPA did not use its CAA section 202(a)(1) authority to launch an entirely
new arena of regulation which Congress had never authorized or instructed the EPA to
enter, whether in CAA section 202 specifically or in any other provision or program
regulating source emissions. Examples illustrating these points are provided in section
2.1.2.1.2. of this document.
EPA Summary of Comments
Commenters stated that the EPA's proposed best reading of the statute, if applied during
the 1970s and 1980s, would have prevented the EPA from regulating lead as a gasoline
additive. Commenters stated that this thought experiment is particularly applicable to the
current proceeding because the endangerment provision in CAA section 211 (c)(1) closely
parallels that of CAA section 202(a)(1). Commenters stated that if the EPA's proposed
rescission is adopted it would be analogous to failing to take action on gasoline lead
additive in the early 1970s, except that this time the adverse consequences might be even
greater. Commenters asserted on this basis that the EPA's proposal does not pass the
"gasoline lead test."
EPA Response
The EPA disagrees with this comment. The interpretation of CAA section 202(a)(1) adopted
in this final action would not bar the EPA from regulating lead under CAA section 211 (c)(1).
The best reading of CAA section 202(a)(1) is that Congress authorized the EPA, when the
Administrator exercised the requisite judgment, to prescribe emission standards in
response to "air pollution" that endangers public health or welfare through local or regional
exposure, not the attenuated, global-concentration causal pathway used in the
Endangerment Findingto expand the provision to global climate change concerns.
Although commenters raise concerns arising under CAA section 211(c)(1), which is a
different provision with different prior regulations not within the scope of this rulemaking,
nothing about the interpretation finalized in this action, even assuming commenters' point
that the provisions are identical, would be consistent with the regulation of lead emissions.
Lead emissions can themselves be considered air pollution that endangers health and
welfare through direct exposure, namely, ingestion in food, paint chips, and dust particles
and inhalation. See Ethyl Corp. v. EPA, 541 F.2d 1, 8-9 (D.C. Cir. 1976) (en banc). When the
EPA began regulating lead emissions under CAA section 211 (c)(1), mobile source
emissions were understood to account for "approximately 90 percent of lead in the air." Id.
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at 9. The EPA has also regulated lead as a criteria pollutant under the NAAQS program
since the late 1970s. See 43 FR 46246 (Oct. 5,1978). And Congress has authorized the
regulation of lead and circumstances involving lead exposure, including by listing lead
compounds as a hazardous air pollutant under CAA section 112(b), and restricting various
lead-containing products and equipment under, for example, the Safe Drinking Water Act
(SDWA).
To the extent commenters suggest that the EPA proposed that only criteria pollutants or air
toxics may be regulated under CAA section 202(a)(1), that is not consistent with the
proposal and not consistent with the interpretation finalized in this action. Rather, the
Agency is finalizing that the "air pollution" the EPA is authorized to regulate under CAA
section 202(a)(1) is that which endangers public health or welfare through local or regional
exposure. The nature of criteria pollutants and air toxics inform this understanding because
they are relevant to the ordinary meaning of the term "air pollution" at the time of
enactment and share such general characteristics, but the list is not exclusive. The
Endangerment Finding is, as determined in this final action, unlawful because it asserted
an effectively unlimited authority to define "air pollution" at the Administrator's discretion
and used that authority in a manner inconsistent with the best reading of the statute.
Moreover, commenters' argument raises additional unanswered questions about the scope
of the EPA's authority under CAA section 211 (c)(1). Were commenters correct that CAA
section 202(a)(1) must be interpreted broadly enough to encompass regulation to address
global climate change concerns and that the scope of CAA sections 202(a)(1) and 211 (c)(1)
are more or less identical, it is not clear what would prevent a future Administrator from
banning gasoline or diesel as a statutory matter. This reinforces the EPA's conclusions that
the interpretation adopted in the Endangerment Finding is fundamentally unsound, both as
a matter of statutory interpretation and in light of the MQD.
2.1.1.1.1 Constructingthe Scope of 202(a)(1) Based on Specific Air
Pollutants Identified in CAA Section 202 and Other CAA Sections
EPA Summary of Comments
Commenters stated that many of the air pollutants listed in the proposal and addressed
elsewhere in the CAA are harmful via complex, indirect, and non-local pathways.
Commenters stated that ground-level ozone and much of PM2.5 are secondary pollutants
formed through atmospheric chemical reactions of precursor species. Commenters stated
that the Mercury and Air Toxics Standards regulate atmospheric mercury, which comes in
several forms: elemental gaseous (Hg°), oxidized elemental (Hg), and particulate Hg.
Commenters stated that approximately 80% of global atmospheric mercury is elemental
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gaseous mercury with an atmospheric lifetime of approximately one year (Selin et al. 2007).
Commenters stated that an atmospheric lifetime of one year is sufficiently long that
atmospheric mercury is transported on hemispheric scales. Commenters stated that it is
estimated that only 20% of mercury deposited in the United States originates from North
American sources (Selin and Jacob 2008). Commenters stated that moreover, the health
damages that result from atmospheric emissions are not through "local and regional
exposure." Commenters stated that, rather, a major source of mercury exposure is via the
consumption of oceanic fish (Selin and Jacob 2008).
Commenters stated that acid rain is not merely a "local or regional" impact from S02 and
NOx pollution. Commenters stated that, rather, winds can blow S02 and NOx over long
distances and across borders making acid rain a problem for everyone and not just those
who live close to these sources. Similarly, commenters stated that smog, another example
mentioned in the proposed rule, likewise is a form of air pollution resulting from CAA-listed
air pollutants or precursors (specifically, NOx and volatile organic compounds (VOCs)) that
can be transported long distances and across national borders. Commenters stated that,
many long-lived pollutants can travel globally, and there is growing evidence for probable
health impacts from ozone and PM traveling over oceans and between continents.
Commenters stated that other Congressionally-listed CAA air pollutants that have
necessitated the United States' international cooperation to address transboundary, and
even trans-oceanic, air pollution transport issues include PM, ozone, and mercury.
Commenters further asserted that the EPA regulates "ozone depleting substances" (ODS)
that impact public health or welfare by depleting the ozone layer in the upper atmosphere.
Commenters stated that ODS are well-mixed air pollutants which endanger human health
by allowing ultraviolet radiation to reach the Earth's surface.
EPA Response
The EPA disagrees with these comments, which mistake transport for local or regional
effects. The Agency acknowledged at proposal and acknowledges in this final action that
"air pollution" is that which adversely impacts health or welfare through local and regional
exposure, whether the air pollution or its precursors are emitted nearby or at a distance.
For example, ozone that transports across jurisdictional boundaries causes adverse
impacts locally and regionally. In other words, to threaten adverse impacts, ozone does not
need to first accumulate in the atmosphere with all other anthropogenic sources of ozone
and its precursors to influence changes at a global scale that then may play a role in local
or regional effects. Similarly, PM that travels into the United States from elsewhere,
whether from just across the border in Canada or from China, also threatens health and
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welfare locally and regionally; additionally, the impacts are not derived from global
concentrations of PM that play a potential causal role in global changes that then may
influence local and regional impacts. Mercury ingested from fish fits the same pattern; the
effects stem from the local presence of the pollution {i.e., in commenter's fish
consumption scenario, ingestion), even if it has traveled a large distance from its emission
source. Finally, that some ozone or some PM may travel far does not mean that there are no
local or regional impacts from those pollutants at their place of origin. Conversely, there is
no plume or tracing with GHGs under the global climate change concern reading adopted
in the Endangerment Finding-the theory required to regulate GHGs under CAA section
202(a)(1) requires aggregating all GHGs into global atmospheric concentrations, and local
or regional exposure to any particular GHG emissions is not the mechanism of harm.
The CAA addresses interstate and international transport of air pollution with local and
regional impacts in various ways - for example, through the "good neighbor" or "interstate
transport" provision, CAA section 110(a)(2)(D), through CAA section 179B (addressing air
quality planning in areas affected by international emissions), and through CAA section 115
(authorizing emissions control requirements for emissions into a country with reciprocal
protections for emissions into the U.S., under certain conditions). These limited instances
authorizing the EPA to consider or regulate in response to international emissions are the
exception, not the rule, and demonstrate that when Congress intended to address
interstate, let alone international air pollution concerns, it provided so expressly. In none of
them did Congress implicitly or expressly authorize the EPA to regulate in response to
global climate change concerns.
The EPA notes that several of the particular examples cited by commenters are particularly
inapt and lend further support to the conclusion that CAA section 202(a)(1) does not
encompass regulation in response to global climate change concerns. With respect to
mercury, Congress itself listed mercury compounds as a hazardous air pollutant to be
regulated under CAA section 112. With respect to ODS, Congress responded to concerns
about the depletion of the ozone layer by enacting a new title of the CAA, Title VI, which
implemented certain commitments under the Montreal Protocol. Those provisions include
detailed requirements and additional authorities that reflect a conscious decision to not
leave it to administrative action to, as with the Endangerment Finding, redefine existing
statutory language to address a fundamentally different problem. Importantly, Congress
considered legislation, including from 2007 to 2009—with at least one major bill
considered and voted on between the proposal and finalization of the Endangerment
Finding in 2009—that would have also added a new title to the CAA including new
authorities and instructions for a comprehensive approach to GHG regulation.
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EPA Summary of Comments
Commenters asserted that the proposal misapplies the noscitura sociis and ejusdem
generis canons. Commenters stated that there is no list to apply either cannon to; instead,
according to commenters, the text of CAA section 202(a)(1) provides that the Administrator
"shall prescribe regulations" establishing standards applicable to emissions of "any air
pollutant" which he judges to cause or contribute to an endangerment, without specifying
any list of specific pollutants he should regulate under this provision.
EPA Response
The EPA disagrees with commenters' assertions and notes that both canons reflect the
general principle that statutory terms should be read in context. Noscitura sociis counsels
that "a word is given more precise content by the neighboring words with which it is
associated," while ejusdem generis informs the meaning of "a general or collective term at
the end of a list of specific items." Fischer v. United States, 603 U.S. 480, 487 (2024). The
Agency is not invoking these canons for the purpose of interpreting the best reading of the
key statutory term "air pollution." In that respect, our approach stems more generally from
the proposition that context matters. See United Sav. Ass'n of Tex. v. Timbers oflnwood
ForestAssocs., 484 U.S. 365, 371 (1988) ("A provision that may seem ambiguous in
isolation is often clarified by the remainder of the statutory scheme — because the same
terminology is used elsewhere in a context that makes its meaning clear,... or because only
one of the permissible meanings produces a substantive effect that is compatible with the
rest of the law.") (citations omitted).
As noted in section V.A.1 of the final action preamble, noscitur a sociis is relevant to
interpreting terms within the statutory definition of "welfare" in CAA section 302(h), which
is generally understood to consist of a list of terms following the phrase "effects on."
EPA Summary of Comments
Commenters argued that the EPA's proposed reading of CAA section 202(a)(1), which they
characterized as "since the CAA doesn't regulate GHGs, they can't be pollutants," is not
consistent with the structure of the CAA. According to these commenters, the CAA has
multiple provisions - sections 108,111,112, 202, and 602 - with the same basic structure:
Congress lists a number of pollutants and allows the Administrator to add additional
pollutants.
Commenters argued that in sum, Congress took no action to limit the list of emissions
covered by CAA section 202 and gave the Administrator authority to add to the list.
Commenters further stated that there is no basis for the EPA to assert that Congress saw
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the auto emission standards it specified in statute by legislation as the "forever-final" list.
Commenters stated that what Congress saw as "forever-final" was the EPA's authority to
respond to conditions that might arise post-enactment. Commenters stated that to that
end, CAA section 202 provided for changes and additions to be made that are not limited to
the pollutants identified by name in the statute.
Commenters stated that the lesson learned in the 1960s was that pollutants could be
widely used for decades before their harms were detected, such that there would have to
be a legal mechanism to prohibit emissions whose harms Congress had not fully
recognized in the 1960s and even the 1970s. Commenters further stated that Congress
acted in response to that context by giving the Administrator the power through an
endangerment mechanism to act on such emerging threats. Commenters stated that it
was clear at the time of enactment, and remains clear ever since, that the purpose of the
CAA was to establish a system that would protect the public over the long term and cover
pollutants not yet identified.
Commenters stated that it makes no sense to construe CAA section 202 as limited by the
pollutants specifically mentioned in section 202 since, as the proposal acknowledged,
CAA section 202(a) was written first and only later did Congress add other provisions
addressing more specific pollutants. Commenters further stated that those later provisions
have little if any probative weight as to the scope of CAA section 202(a) {i.e., Congress did
not "omit" any pollutants), especially because, according to commenters, Congress has
only ever amended section 202(a) to make its scope broader, not narrower. In support,
commenters referenced the Supreme Court's decision in Loper Bright which they
characterized as stating that "every statute's meaning is fixed at the time of enactment."
EPA Response
The EPA disagrees with commenters' understanding of the structure and regulatory
scheme of the CAA. The text, context, and structure of CAA section 202(a)(1) support the
conclusion that the provision addresses air pollution that is different in kind from the global
climate change concerns underlyingthe Endangerment Finding, which redefined the
nature of air pollution in order to extend the EPA's authority to GHG regulation. This is
evidenced by the different mechanisms of action of air pollutants that are listed for
regulation throughout the CAA and, also, by the ways that Congress expressly and
separately authorized regulation when it intended the EPA to address problems of a
different nature, for example, ODS in Title VI, hydrofluorocarbons (HFCs) in the American
Innovation and Manufacturing (AIM) Act, and the statute's limited number of provisions
referencing international emissions transport for particular purposes. Separately, the
Agency does not agree with commenters' representation about the similarities between a
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number of very different statutory provisions. Although there are similarities in the
language triggering the EPA's authority to regulate under CAA section 111 and CAA section
202 for example (with the caveat that CAA section 111 uses the phrase "significantly
contribute,"), CAA section 112 is different in that it includes a long list of pollutants that
Congress itself identified as hazardous air pollutants to be regulated, with a different
process for the Administrator to list, and potentially delist, certain hazardous pollutants
under certain conditions.
The EPA agrees, at a high level, with commenters' suggestions that Congress sought to
leave the Agency with flexibility to prescribe standards as understanding of the pollutants
contributing to the air pollution of concern in the 1960s and 1970s developed. For example,
the legislative history cited in section V.A.1 of the final action preamble, including
committee reports in floor statements, include explanation of how greater understanding
of the air pollutants and air pollution under discussion at that time (e.g., PM, S02, and NOx)
and of legislators' understanding that the EPA and its precursor or partner agencies were
developing or reviewing additional research on those pollutants. But the Agency parts
company with commenters to the extent they suggest that the statute must be read as
conferring unbridled authority on the EPA to redefine the scope of its own authority to
address emerging problems. That understanding is inconsistent with Loper Bright, in which
the Court specifically noted that a deferential posture is least appropriate when an Agency
is construing its "own power." 603 U.S. at 401. Even if the statute could be read in that way,
avoidance principles would counsel against adopting it as the best reading of the statute
for nondelegation reasons. And it would be unclear under what theory commenters believe
the statute would not run afoul of the nondelegation doctrine to the extent the Agency-as it
did in the Endangerment Finding-utilized that arguable breadth to assert a novel authority
to assert an unheralded power over a major policy question.
Finally, the EPA notes that during the first 40 years of this provision's history, encompassing
rulemakings for many different classes and categories of motor vehicles, the Agency
limited the scope of its regulations under CAA section 202(a)(1) to the air pollutants and air
pollution problems Congress identified in more specific provisions in CAA section 202. And
prior to 2009, the EPA did not use its CAA section 202(a)(1) authority to launch an entirely
new arena of regulation which Congress had never authorized or instructed the EPA to
enter, whether in CAA section 202 specifically or in any other provision or program
regulating source emissions. Examples illustrating these points are provided in section
2.1.2.1.2. of this document.
EPA Summary of Comments
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Commenters stated that non-regulatory CAA references to GHGs demonstrate
congressional intent to regulate GHGs. Commenters stated that more importantly, the first
two purposes of the CAA are: (1) to protect and enhance the quality of the Nation's air
resources so as to promote the public health and welfare and the productive capacity of its
population; (2) to initiate and accelerate a national research and development program to
achieve the prevention and control of air pollution. Commenters stated that if Congress
included research and grant programs with regards to GHGs, that is because Congress
considered them air pollutants. Commenters stated that combiningthe research and
grants conducted on air pollutants with the CAA's provisions requiring it to expand the list
of pollutants when the correct information is presented means that the EPA, in regulating
GHG emissions from motor vehicles and other sources, is doing exactly what Congress
intended, consistent with the structure of the CAA.
EPA Response
The EPA disagrees with commenters' interpretation of non-regulatory CAA references to
GHGs. That Congress has referenced GHGs in non-regulatory contexts does not evince an
intent to authorize regulation-that Congress considered the issue but never provided such
regulatory as relevant here strengthens, rather than undermines, the conclusion that there
is a difference in kind between GHGs and global climate change concerns and the "air
pollution" targeted by CAA section 202(a)(1). That was true before the 2009 Endangerment
Finding to the extent Congress created various research programs. And it has been true
since, e.g., in the Inflation Reduction Act (IRA). We note also that the One Big Beautiful Bill
Act (OBBB) repealed or rescinded a number of provisions of the IRA concerning GHGs and
climate change. For further discussion of this development, and that Congress has
considered, but failed to adopt, legislation that would have expressly authorized GHG
regulation and that Congress has recently taken issue with EV mandates and GHG
regulations by disapproving under the CRA California preemption waivers for regulations
that included more stringent GHG limitations than Federal GHG emission standards, up to
and including a mandatory transition to EVs, see section 2.1.2.1.3 of this document.
With respect to the CAA section 101 findings and declarations of purpose, the EPA
disagrees that this language supports commenters' view. See 42 U.S.C. § 7401. Rather,
Congress repeatedly describes air quality challenges by references to particular localities,
including urbanization and metropolitan areas, as well as State and regional air quality
control programs. Commenters offer no persuasive reason to think that Congress would
emphasize in findings and purposes the importance of State and local programs and State
and local responsibilities in addressing air pollution if Congress had in mind global climate
change concerns and emissions measured at the global scale.
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Finally, the EPA notes that commenters emphasize "air pollutant" rather than "air
pollution," which is a critical distinction in CAA section 202(a)(1) given the predicate
requirement that the Agency may only prescribe standards when air pollutant emissions
contribute to "air pollution which may reasonably be anticipated to endanger public health
or welfare." Regardless whether GHGs are considered air pollutants, the Agency may only
regulate GHG emissions if such emissions contribute to "air pollution," an undefined term
that must be given its ordinary, contemporary meaning and read in context with the
proximate cause limitations in the phrase "reasonably be anticipated to endanger."
EPA Summary of Comments
Commenters stated that the CAA does reference GHGs in a regulatory context. These
commenters argued that the Renewable Fuel Standard (RFS) program, 42 U.S.C. § 7545(o),
reflects that Congress has already reached a legislative judgment that GHG emissions from
the transportation sector "contribute" to climate change, are problematic, and should be
reduced.
Commenters stated that in several provisions, the CAA lists GHGs alongside other
regulated "pollutants," reinforcing that Congress intended and treated these pollutants as
similar for purposes of the CAA. One commenter went on to point to CAA provisions at 42
U.S.C. § 7403, 7433(d)(3)(A), and § 7438(a)(2).
Commenters stated that assertingthat the regulation of GHGs underthe CAA was
"unprecedented" is incorrect and offered several contentions in support: 1) 7/1 /92 The
EPA's venting prohibition under CAA section 608 made it illegal for technicians to knowingly
release ozone-depleting refrigerants (chlorofluorocarbons (CFCs) like R-12) during the
service, repair, or disposal of Motor Vehicle Air Conditioner (MVACs); 2) 11/15/95 The
venting prohibition was extended to include non-ozone-depleting substitute refrigerants,
because of their high global warming potential; 3) 3/22/94 The EPA regulated NOx from
some fossil combustion, primarily because it formed acid rain, which acidified lakes. C02
formed from combusting fossil fuels acidifies the oceans; and 4) 2/10/95 The EPA began
regulation of SOx for the same reason.
EPA Response
The EPA disagrees with commenters' assertions regarding the RFS program, which is
further evidence for the conclusion that when Congress has wanted to address GHGs, it
does so expressly and in a different manner. CAA section 202 does not expressly reference
GHGs, and the RFS program operates differently than and does not go as far as
commenters suggest.
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Congress expressly prohibited attempts to read the RFS program as an authorization to
regulate GHGs under other sections of the CAA. The RFS program's authorizing language at
CAA section 211(o)(12) provides that "[n]othing in this subsection, or regulations issued
pursuant to this subsection, shall affect or be construed to affect the regulatory status of
carbon dioxide or any other greenhouse gas, or to expand or limit regulatory authority
regarding carbon dioxide or any other greenhouse gas, for purposes of other provisions ...
of this chapter." What commenters attempt is disallowed by the CAA. This express
statutory prohibition on using the RFS program to redefine and expand other CAA
authorities further reinforces the EPA's view, expressed at proposal, in the final action
preamble, and this document, that Congress uses specific language when it addresses
GHGs and has not done so in CAA section 202(a)(1) or any other provision bearing on the
interpretation of CAA section 202(a)(1).
With respect to the specific language of the RFS program, the provision references "climate
change" at CAA section 211 U.S.C. §(o)(2)(B)(ii)(l) in a context that does not address
regulation in response to global climate change concerns generally. The EPA is to set
applicable volumes based, in part, on "an analysis of" "the impact of the production and
use of renewable fuels on the environment, including air quality, climate change,
conversion of wetlands, ecosystems, wildlife habitat, water quality, and water supply," as
well as other factors listed in the statute. This supports the EPA's conclusion that Congress
knows how to expand the CAA to encompass such concerns, but has not in CAA section
202(a)(1). When Congress thought it relevant, it included climate change as a separate
consideration from air quality. It did not view climate change as encompassed within
general "air quality." Finally, we note that "climate change" is only one of many factors
considered in setting volumes under the RFS program, including the need for
transportation fuel, costs to consumers, and energy security.
CAA section 211 (o) also defines certain renewable fuels encompassed within the program
to include GHG reduction requirements. Though the program historically required
increasing amounts of renewable fuels (which definitionally must meet certain GHG
reduction requirements), these references are specific to the RFS program and, again,
notably do not apply to other parts of the CAA. See CAA section 211 (o)(12).
Other statutory provisions cited by commenters are nonregulatory provisions. For the EPA's
response to this and similar arguments, see the response previously offered in this section
of this document.
The EPA further disagrees that commenters' references to four EPA actions from the 1990s
present examples where the EPA relied on the global climate change theory. Both examples
under CAA section 608 occur in CAA Title VI, which Congress specifically enacted to
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address global pollutants that impact the stratospheric ozone layer. Rather than an
endorsement of the global climate change theory, CAA section 608 reinforces that
Congress has expressly addressed multijurisdictional pollution problems in various ways;
but in none of them did Congress implicitly or expressly endorse the global climate change
GHG theory. When Congress has addressed interstate and international problems, it used
language much more specific than can be found in CAA section 202(a)(1). The remaining
two examples cited by commenters' addressed air pollution that threatens public health or
welfare through local or regional exposures and not under global climate change theory.
Specifically, both the March 22,1994 action and the February 10,1995 action cited by
commenters were taken pursuant to the EPA's Acid Rain Program authority in Title IV of the
CAA, a program designed to reduce emissions of NOx and S02, both precursors to acid rain.
See 59 FR 13538 (Mar. 22,1994) (final action taken to implement Acid Rain NOx Emission
Reduction Program in CAA section 407, the primary purpose of which is "to reduce the
adverse effects of acidic deposition on natural resources, ecosystems, visibility, materials,
and public health by substantially reducing annual emissions of NOx, a principal acidic
deposition precursor, from coal-fired electric utilities"); 60 FR 7962 (Feb. 10,1995) ("Notice
of the 1995 EPA S02 allowance auctions" under CAA section 416). Precursors to acid rain
interact locally and regionally with additional airborne chemicals to form acidic
precipitation.
EPA Summary of Comments
Commenters stated that legislative history and subsequent congressional action
demonstrate that GHGs are air pollutants subject to regulation under the CAA.
Commenters' point to discussions cotemporaneous with the development of the 1970 CAA
that the statute should address global climate change, including discussions between key
Senators and administration officials as well as a 1970 report from President Richard
Nixon's task force on air pollution. Commenters stated that written and oral exchanges -
both inside and outside Congress - categorized C02 as a form of "air pollution" and
recognized its probable effects on weather and global climate. Commenters stated that
given this context, the term "air pollution" in CAA section 202(a)(1) should not be read to
limit the EPA's regulatory authority to forms of air pollution that threaten public health and
welfare through "local or regional exposure" alone. Commenters stated that, rather, the
broad language of CAA section 202 meant to allow for the eventual regulation of all air
pollution shown to endanger public health or welfare. Commenters stated that repeated
historical references to the emission of C02 as a form of "air pollution" undermine the EPA's
proposed reading of the statute and yet go unaddressed in the Agency's proposal.
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Commenters stated that CAA section 157 was added to "respond[] to the threat that
release of certain materials ... into the environment may indirectly endanger public health
and welfare by causing or contributing to significant depletion of the stratospheric ozone
layer." Commenters stated that, in a nutshell, Congress was concerned that pollution
released in the United States would enter the stratosphere, deplete the ozone layer, and
cause indirect effects on health and welfare through increased sun exposure - the types of
impacts that, like those from GHGs, are indirect, the product of a long causal chain, and
not produced through "local or regional exposure."
Commenters stated that, as the House Report accompanying the 1977 CAA Amendments
clearly explains, Congress intended the EPA to consider endangerment to public health or
welfare under CAA section 202 the same as it would under the other provisions with the
similar endangerment framework, including CAA section 157. Commenters stated that
Congress's mandate that the EPA consider endangerment under CAA sections 157 and 202
similarly, with an emphasis on valuing protection of public health, thus strongly indicates
that the EPA must consider indirect impacts to public health and welfare that result from
motorvehicle GHG emissions.
Commenters stated that the EPA should recognize that Congress directed the EPA to
achieve greater GHG emissions reductions in the IRA using the authority of the CAA.
Commenters stated that this directly contradicts the EPA's proposed position that the
Agency has no authority to address GHGs.
Commenters stated that Congress created several new programs under the 2022 budget
reconciliation act. Commenters stated that in more than a dozen places that legislation
specified "[t]he term 'greenhouse gas' means the air pollutants carbon dioxide,
hydrofluorocarbons, methane, nitrous oxide, perfluorocarbons, and sulfur hexafluoride."
Commenters stated that one of the programs was repealed by the 2025 budget
reconciliation act, but the others were not, and their definitional language remains in
effect.
Commenters stated that Congress neither proposed nor directed the EPA to repeal the
Endangerment Finding in the IRA or OBBBA. Commenters stated that, if anything,
Congress's silence on this issue indicates acquiescence in and acceptance of the
Endangerment Finding. Commenters stated that, moreover, to the extent Congress has
spoken in legislation to GHGs since 2009, it has relied on and confirmed the Supreme
Court's decision in Massachusetts. Commenters stated that, for example, Congress relied
on the EPA's authority to regulate methane emissions from the oil and gas sector when
imposing the waste emissions charge in the IRA and when delaying, but not eliminating, the
charge in the OBBBA.
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Commenters stated that Congress had both ample opportunity and direction: it could have
expressly rejected the holding in Massachusetts; amended the CAA in response to West
Virginia, where the Supreme Court indicated no issue with the Endangerment Finding; or
expressly delegated the authority to limit the definition of an "air pollutant" to the Agency,
as prescribed in Loper Bright. Commenters stated that, instead, it has done the opposite -
expressly providing that GHGs are pollutants in the IRA and OBBBA.
Commenters stated that after Mass v. EPA, lawmakers repeatedly failed secure passage of
the numerous bills they introduced into Congress attempting to redefine "pollutant" in the
CAA to exclude GHG emissions.
Commenters stated that Congress has repeatedly funded the EPA's budget requests for the
purpose of issuing and enforcing GHG regulations under CAA section 202 indicating
Congressional recognition of that authority.
Commenters stated that rescinding the Endangerment Finding on the basis of "history" of
CAA section 202(a) is contrary to controlling precedent. Commenters stated that Circuit
Judge Janice Brown's eloquent dissent from the denial of rehearing (in Utility Air) attempted
to construct an argument from legislative history that, while illuminating, simply does not
bear out a Congressional determination that the CAA did not authorize the Endangerment
Finding. Commenters stated that, recognizing this fact, Judge Brown allowed that she was
bound, albeit "reluctantly," to "concur with the Panel's determination that the EPA may
regulate GHGs in tailpipe emissions."
EPA Response
The EPA does not agree that the legislative history of the CAA or subsequent developments
demonstrate that GHGs may lawfully be defined as "air pollution" under CAA section
202(a)(1).
Commenters point to CAA section 157, which the 1990 CAA Amendments repealed and
incorporated into the Title VI provisions for stratospheric ozone protection. Pub. L. 101-549,
104 Stat. 2648. This example reinforces the EPA's view, expressed throughout the final
action preamble and this document, that when Congress has wanted to address global
issues, it expressly legislates to do so. Similar legislation creating one or more new titles in
the CAA addressing GHGs and global climate change concerns was introduced between
2007-2009 but not enacted by Congress. Attempts to draw similarities between CAA
section 157's and CAA section 202's endangerment frameworks do not undercut the EPA's
reasoning. As discussed elsewhere in this document, the commenters' focus on the
"endangerment principle" does not answer the question whether GHG regulation in
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response to global climate change concerns is different in kind from the air pollution
addressed by CAA section 202(a)(1).
References to legislative history in these comments do not override the EPA's analysis.
These discussions are generally vague and not controlling in any case. Legislative history
cannot trump plain text, as the text is what Congress as a whole enacted. There is no
dispute that Congress never enacted language dealing with GHGs in CAA section 202(a)(1)
despite its potential awareness of global climate change concerns.
More recent legislative developments cannot override the text of CAA section 202(a),
either. Though the 2022 IRA added, through a reconciliation bill, references to GHGs in a
handful of places within the CAA, the OBBB expressly repealed one such provision and
rescinded funding for others. The examples cited by commenters were non-regulatory
provisions, and all of the definitions applied only "under this section." Nor did any of these
provisions do more than associate the term "air pollutant" with GHGs, which does not
answer the question whether GHGs can lawfully be defined as "air pollution" for regulatory
purposes under CAA section 202(a)(1). That is not enough to transform the regulatory text
of CAA section 202(a)(1) to extent to GHGs under the global climate change theory.
The EPA's analysis rests on "air pollution" as used in CAA section 202(a)(1), not on the CAA-
wide definition of "air pollutant." As noted at proposal and in the final action, the EPA
continues to have obligations to regulate certain GHGs in particular ways (e.g., HFCs) and
could regulate others when the standard applies and is satisfied (e.g., GHGs that can, in
certain contexts, harm health or welfare through local or regional exposure).
The EPA disagrees with commenters' claim that Congress's silence on the EPA's authority
to regulate GHGs indicates "acquiescence" in and acceptance of the 2009 Endangerment
Finding (or, for that matter, the overbroad reading of Massachusetts relied upon in the
Endangerment Finding and espoused by certain advocates). For decades, the Supreme
Court has relied on congressional acquiescence only where overwhelming evidence
indicates Congress considered and rejected the precise issue before the court. See
Rapanos v. United States, 547 U.S. 715, 750 (2006) (acknowledging congressional
acquiescence when there is "evidence that Congress considered and rejected the 'precise
issue' presented before the Court" but that, "[ajbsent such overwhelming evidence of
acquiescence, we are loath to replace the plain text and original understanding of a statute
with an amended agency interpretation"); AMG Cap. Mgmt., LLC v. FTC, 593 U.S. 67,
81 (2021) ("when 'Congress has not comprehensively revised a statutory scheme but has
made only isolated amendments... [i]t is impossible to assert with any degree of assurance
that congressional failure to act represents affirmative congressional approval of [a court's]
statutory interpretation'") (quoting Alexander v. Sandoval, 532 U. S. 275, 292 (2001)); cf.
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Bob Jones Univ. v. United States, 461 U.S. 574(1983) (finding congressional acquiescence
in longstanding and publicly known Internal Revenue Service (IRS) policy, where Congress
repeatedly reenacted the tax code without disturbing the policy and rejected bills that
would have overturned the IRS interpretation).
Commenters fail to cite any "overwhelming evidence" of congressional acquiescence with
respect to the 2009 Endangerment Finding. Congress did not revise CAA section 202(a)(1)
or its related provisions at any time after the 2009 Endangerment Finding, so there are no
legislative action that, like those highlighted by the Supreme Court in Bob Jones, manifest
congressional acquiescence to the Endangerment Finding. In Bob Jones, the Court
highlighted a combination of congressional action and inaction as evidence that Congress
had acquiesced in the IRS's interpretation of 26 U.S.C. § 501 (c)(3) as denying tax-exempt
status to private schools that practice racial discrimination. 461 U.S. at 599-600. Congress
held its first hearings "on this precise issue" only one month after the IRS announced its
position in 1970 and subsequently held additional exhaustive hearings on the same issue.
Id. Moreover, during the 12-year period following the IRS's announcement of its
interpretation, Congress rejected 13 bills introduced to overturn the IRS's interpretation of
26 U.S.C. § 501 (c)(3), while enacting numerous other amendments to 26 U.S.C. § section
501, including an amendment to section 501 (c)(3) itself. Id. The Supreme Court found that
"Congress affirmatively manifested its acquiescence in the IRS policy when it enacted the
present 501 (i) of the Code,... [which] denies tax-exempt status to social clubs whose
charters or policy statements provide for 'discrimination against any person on the basis of
race, color, or religion.'" Id. at 600. In contrast to these facts, Congress has taken no actions
on the precise question whether the EPA is authorized to regulate GHG emissions, nor has
it enacted any amendments to the CAA that affirmatively manifest its acquiescence in the
EPA's articulation of its authority in the Endangerment Finding.
As to the commenter's claim that Congress relied on the EPA's authority to regulate
methane emissions from the oil and gas sector when imposingthe waste emissions charge
(WEC) in the IRA and when delaying, but not eliminating, the WEC in the OBBB, these
comments are not on point. Congress's references to the EPA's section 111 standards for
methane emissions in CAA section 136, the provision underlying the WEC rule,4 do not
address the precise question whether the EPA is authorized to regulate GHGs from new
motor vehicles and engines. Likewise, nothing in the OBBB manifests congressional
acquiescence in the Endangerment Finding.
4 On May 19, 2025, President Trump signed into Law a resolution adopted by Congress under the
Congressional Review Act (CRA) to void ourfinal rule implementingthe WEC added to the CAA in 2021.
Pub.L.119-2; see 90 FRFR 21225 (May 19, 2025).
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Congress has expressly adopted EPA actions in the CAA (e.g., CAA section 112 and the
Benzene NESHAP), but has not done so here.
With respect to co mm enters' reliance on Coalition for Responsible Regulation and
American Lung Association, neither of those cases squarely addressed the specific
arguments the Agency is now making concerning the best reading of CAA section 202(a)(1).
To the extent both endorsed a broad interpretation of the EPA's authority over GHGs, both
have been reversed or called into question in substantial part, in UARG and in West
Virginia, among other Supreme Court decisions. The EPA also disagrees with one
commenter that opined that the Supreme Court in UARG affirmed the validity of the 2009
Endangerment Finding., as discussed further in this response as well as RTC sections
2.1.1.1.7 and 2.1.2. Further, those holdings have been further called into question by
Michigan (in which the Supreme Court said it would be unreasonable for costly regulations
to be issued that do not have any benefit), and Loper Bright (in which the Supreme Court
held that no deference should be afforded to agencies in their statutory interpretations and
that all statutes only have one best meaning that is fixed at the time the statute was
enacted).
Specifically, in Coalition, the D.C. Circuit only rejected six specific arguments that
petitioners had raised against the Endangerment Finding. See 684 F.3d 102,117. The court
did not grapple with the fact that GHGs may be air pollutants but, as we now argue, are still
not "air pollution" of the kind Congress intended the EPA to regulate under CAA section
202(a)(1), or our conclusion now that any regulation of GHGs from motor vehicles in the
United States would be futile to address global climate change. To be sure, the court
upheld the EPA in rejecting petitioners' claims that that there would be no "meaningful
mitigation" of GHG emissions from the Tailpipe rule, but the court only focused on the fact
that 960 million metric tons of C02 equivalent would be avoided over the lifetime of the MY
2012-2016 vehicles. Id. at 128. We now contend that, regardless of any tonnage-reduction
estimates, all of the GHG reductions that the EPA has achieved, or could possibly achieve,
under CAA section 202(a)(1) is futile because it won't in any way contribute to solving the
global warming problem. Thus, this record is like the one in Chemical Manufacturers Ass'n
v. EPA, 217 F.3d 861 (D.C. Cir. 2000), because "nothing in the record suggests" regulation of
GHGs under CAA section 202 "will, directly or indirectly, further the Clean Air Act's
environmental goals." Id. at 867; cf. Coalition, 684 F.3d at 128.
Similarly, American Lung Association had upheld the EPA's finding under CAA section 111
that GHG emissions from power plants contribute significantly to the endangerment of
public health and welfare, relying in part on the analysis in Coalition. See 985 F.3d 914, 977.
But there again, the D.C. Circuit only upheld the EPA's reasoning at the time that the United
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States was the second largest emitter of GHGs in the world and that one-third of those
emissions were from coal-fired power plants. Id. Regardless of whether concluding that
level of emissions is not significant would make it "nigh impossible for any source of
greenhouse gas pollution to cross that statutory threshold," id., it is still the case that a
costly regulation with no benefit is not justified. See Michigan v. EPA, 576 U.S. 743, 752
(2015) ("One would not say that it is even rational, never mind 'appropriate,' to impose
billions of dollars in economic costs in return for a few dollars in health or environmental
benefits.").
While the Supreme Court declined to grant certiorari to review the D.C. Circuit's holdings
on the Endangerment Finding in Coalition, it did review a separate issue in UARG, and in so
doing, called into question at least some of the basis for the D.C. Circuit's holdings
upholdingthe Endangerment Finding. The UARG Court explained that even if GHGs are
encompassed in the CAA's definition of "air pollutant," where that term "appears in the
Act's operative provisions, the EPA has routinely given it a narrower, context-appropriate
meaning." 573 U.S. 302, 316. UARG acknowledged that regulation of GHGs under CAA
section 202 was not "contrary to 'common sense,"' because it would only "require EPA to
take the modest step of adding greenhouse-gas standards to the roster of new-motor-
vehicle emission regulations, id. at 318-19, but for the reasons explained in the final action
preamble, we now conclude that under the principles of UARG, West Virginia, Michigan,
and Loper Bright, the best reading of CAA section 202(a)(1) is that GHGs do not create the
kind of "air pollution" that endangers public health or welfare. In other words, the more
careful evaluation of the statutory context-specific analysis UARG called for leads us to a
different conclusion than we had previously reached concerning the CAA section 202(a)
authority.
Similarly, while the Supreme Court did not grant certiorari on the D.C. Circuit's ruling in
American Lung Association upholdingthe EPA's endangerment finding under CAA section
111, in West Virginia, the Court did take another step toward narrowing the putative
holdings of Massachusetts, by again constraining the EPA only to those regulatory
measures for GHGs authorized by the statute, regardless of the dangers posed by global
climate change. 597 U.S. 697, 727, 730.5 The dissenters themselves acknowledged this:
"Today, the Court strips the [EPA] of the power Congress gave it to respond to 'the most
pressing environmental challenge of our time.'" 597 U.S. 697, 753 (Kagan, J., dissenting)
5 In his dissent in American Lung Association, Judge Walker also identified that the holdings in Massachusetts
left many questions unresolved regarding specifically whether and how, under the CAA's various provisions,
GHG regulation could be done. "Does the Clean Air Act direct the EPA to make our air cleaner? Clearly yes.
Does it require at least some carbon reduction? According to Massachusetts v. EPA, again yes. But how
should the EPA reduce carbon emissions from power plants? And who should pay for it? To those major
questions, the Clean Air Act's answers are far from clear." 985 F.3d 914,1002 (Walker, J., dissenting).
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(quoting Massachusetts, 549 U.S. at 497). Because the CAA, properly construed, does not
allowfor meaningful regulation of GHG emissions from mobile sources (as explained in the
final action preamble), it must therefore be the case that regulation of GHG emissions at all
from these sources is not what Congress intended.
In reaching their holding, the majority in West Virginia also made clear that its decision in
American Electric Power v. Connecticut was not a license to the EPA to regulate GHGs
however it may want simply because they may be "air pollutants." 597 U.S. at 730. Rather,
the Court explained, the American Electric Power decision merely held that the CAA had
displaced federal common law claims with respect to GHG emissions. Id. Even though the
CAA displaced federal common law, still, the EPA is constrained to regulate only in "the
ways in which Congress intended EPA to exercise its power." Id. Here, as explained in the
final action preamble and elsewhere in this document, the language of CAA section
202(a)(1) does not authorize the regulation of GHGs from motor vehicles, because GHGs,
while "air pollutants," do not create "air pollution," and any regulation under that provision
to address the global climate problem would be futile.
In conclusion, Coalition for Responsible Regulation and other prior decisions interpreting
Massachusetts to support the EPA's authority to regulate GHGs must be read in light of
subsequent Supreme Court decisions, and those decisions all support the EPA's
conclusion that the regulation of GHGs under the operative language of CAA section
202(a)(1) is not permissible. See final action preamble section VI.A.
The commenters' appeal to congressional funding of the EPA's budget requests does not
indicate that it conferred authority to regulate GHGs under CAA section 202. The EPA's
budget requests for general programs tend to result in broad appropriations language.
2.1.1.1.2 Dictionary Definitions of "pollutant", "pollution", and "air
pollution" support EPA's best reading
EPA Summary of Comments
Commenters stated that the EPA may not isolate individual terms to avoid applying the
CAA's statutory definition of air pollutant. Commenters stated that the EPA's claim that it
may seek out definitions of the other "undefined terms" like "pollutant" is equally baseless.
Commenters stated that the term "pollutant" is not used in CAA section 202(a)(1); the term
"air pollutant" is. Commenters argued that thus, the fact that the term "pollutant," standing
alone, is undefined is irrelevant. Commenters stated that the EPA cannot, by looking in the
dictionary for "pollutant" rather than "air pollutant," substitute definitions in those outside
dictionaries for definitions provided in the CAA itself. Commenters stated that "[w]hen
Congress takes the trouble to define the terms it uses, a court must respect its definitions
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as 'virtually conclusive.'" Kirtz, 601 U.S. at 59-60 (quoting Sturgeon, 587 U.S. at 56);
Stenbergv. Carhart, 530 U.S. 914, 942 (2000).
EPA Response
The EPA disagrees that the proposed and final action isolates words to improperly interpret
CAA section 202(a)(1). The term "air pollution" is critical in CAA section 202(a)(1), as that is
the term that air pollutants must cause or contribute to and the term that must endanger
public health or welfare. The proposal and final action discuss "pollutant" because it
informs the ordinary meaning of "air pollution," an undefined term. Though "air pollutant" is
defined broadly, per Massachusetts, "air pollution" is a different term. The EPA does not
attempt to sever "air" from "pollutant" by reference to the defined statutory term "air
pollution."
EPA Summary of Comments
Commenters stated that the proposal ignores the word "any" in CAA section 202(a).
Commenters stated that the word "any" instead makes clear Congress's intent to make
CAA section 202(a) applicable to the broadest possible range of air pollutants falling within
CAA section 302(g)'s "capacious" definition. Commenters stated that the term "any" has
an expansive meaning that is "one or some indiscriminately of whatever kind." Dep'tof
HUDv. Rucker, 535 U.S. 125, 131 (2002).
Commenters stated that the Court in Massachusetts found the EPA's reading "foreclosed"
by the plain text of the statute. Id. Commenters stated that the Court held that, "[o]n its
face, the definition embraces all airborne compounds of whatever stripe, and underscores
that intent through the repeated use of the word 'any.'" Id. at 529; see also Rucker, 535 U.S.
at 131 (observing that "'any'... has an expansive meaning, that is, one or some
indiscriminately of whatever kind" (some internal quotation marks omitted)); Ali v. Fed.
Bureau of Prisons, 552 U.S. 214, 219 (2008) (same); Babb v. Wilkie, 589 U.S. 399, 405 n.2
(2020) (same).
EPA Response
The commenters emphasis on "any" as applied to air pollutant misunderstands the EPA's
reasoning. We do not rest our conclusion on "air pollutant"-the breadth identified in
Massachusetts is consistent with our conclusion here. We agree that the CAA defines its
overall scope by adopting a broad view of "air pollutants," but that limitations embedded
within individual regulatory provisions determine whether and how the EPA may regulate
particular air pollutants in particular contexts. In CAA section 202(a)(1), that context is (the
emission by new motor vehicles and engines of) any air pollutant that causes or
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contributes to air pollution that may reasonably be anticipated to endanger public health or
welfare. "Any" does not modify "air pollution."
EPA Summary of Comments
Commenters stated that the definitions cited by the EPA do not support the proposed
limiting construction of air pollution and air pollutant. Commenters stated that the
dictionary definitions the EPA cites do not even support its contention. Commenters stated
that it is a logical and linguistic leap to go from the cited definitions -"[a] poisonous or
noxious substance that contaminates the environment," "[t]he harmful addition of a
substance or thing into the environment," and the release of "[c]ontaminants into the
atmosphere"-to the definition the EPA invents: "air pollution... that itself endangers public
health or welfare through local or regional exposures.
Commenters stated that the common understanding of "air pollution" comfortably
embraced GHG pollution of the upper atmosphere long before the 2009 Endangerment
Finding and decades prior to the law dictionary publication the EPA cites, citing literature
commenters assert discuss GHG emissions in terms fitting definitions of "air pollution"
included in the EPA's proposal.
EPA Response
The dictionary definitions cited in the proposed and final action confirm that "air pollution"
involves exposure to harmful airborne substances. That supports the understandingthat
"air pollution" is that which adversely impacts public health and welfare through local and
regional exposure. Dictionary definitions contemporaneous with the enactment of the 1970
CAA Amendments further confirm the EPA's view. Pollution is "[t]he contamination of soil,
water, or the atmosphere by the discharge of noxious substances." Am. Heritage Dictionary
(1970). The emphasis is on the introduction of a contaminant, as discussed in the
proposed and final action. Another contemporaneous definition -that of pollutant- also
supports our view: "[a]nything that pollutes; especially' 'any gaseous, chemical, or organic
waste that contaminates air,' soil, or water." Am. Heritage Dictionary (1970). These
definitions are especially significant when considered against the backdrop of the 1970
CAA Amendments, which defined "air pollutant" in CAA section 302(g) for the first time,
introduced that term into CAA section 202(a)(1), and restructured CAA section 202(a) into
its modern form. As noted in the final action, judicial usage around the time of the 1970
amendments confirms our view. See, e.g., Washington v. GM Corp., 406 U.S. 109,115-16
(1972).
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2.1.1.1.3 Whether GHGs Fall Within the Scope of 202(a)(1) Based on the
CAA's reference to Specific Air Pollutants
EPA Summary of Comments
Commenters stated that GHGs do cause harm to public health and welfare through direct
exposure. Commenters stated that elevated C02 levels directly cause acidification of
water, including oceans, one of the listed "welfare" effects in the CAA. Commenters stated
that the mechanism by which the ocean acidifies is through direct exposure to C02 in the
ambient air, and that this effect can be felt locally. See 87 FR at 14,365-66 & n.317 (citing
studies and noting that "waters... off the coast of Southern California[] have already
acidified more than twice as much as the global average").
Commenters stated that, similarly, the proposal apparently acknowledges that acid rain is
the proper subject for EPA regulation, but suggests that ocean acidification is not.
Commenters stated that it makes no sense to suggest that Congress was giving the EPA
authority to address acidification of the environment when it is the result of S02 but not
when it is the result of C02. Commenters stated that it is incoherent to suggest that GHGs
only "lead to" ocean acidification but S02 itself endangers ecosystems.
Commenters stated that there are over 2,000 studies and reports that link oil and gas
infrastructure to several health issues, including increases in asthma rates and cancer
clusters. A study commissioned by the Pennsylvania Department of Health ("PADOH")
found increased asthma and lymphoma rates and worse birth outcomes. The study stated
that families in Washington and Greene counties, PA have experienced tragedies while
living near gas wells. The study claimed that families have lost children to cancer because
they were unlucky enough to live next to tracking or other oil and gas infrastructure.
Commenters go on to describe harmful impacts of power plants and related traffic harm as
part of their assertion.
Commenters stated that methane is also the primary contributor to the formation of
ground-level ozone, which is itself a GHG that harms human health. Commenters stated
that health effects of breathing ground-level ozone include decreased lung function,
inflammation of airways, and respiratory symptoms like coughing, throat irritation, chest
tightness, and shortness of breath.
EPA Response
The EPA does not agree with comments asserting that GHG "air pollution" causes local or
regional effects within the scope of CAA section 202(a)(1 )'s endangerment requirement.
The Endangerment Finding itself expressly admitted that the circumstances it addressed
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were "unique" because "[n]one of th[e] human health effects" identified in the
Endangerment Finding "are associated with direct exposure to greenhouse gases." 74 FR
66527. Ocean acidification receives only a brief mention in the Endangerment Finding and
is described as an emerging issue. 74 FR 66511. It was not a consequence of the global
climate change theory we are rejecting in this final action.
The commenter's assertion that "welfare" includes ocean acidification misreads the
statute. This view is a serious stretching of the term "water" when read in the proper
context (soils, crops, vegetation, etc.). The effects of ocean acidification were considered
in the 2009 Endangerment Finding and played a minor role. Even under the Endangerment
Finding's own flawed terms, ocean acidification effects were not sufficient to justify
regulating GHGs under CAA section 202(a)(1). This attack also suffers from flaws identified
in the proposed and final action's discussion of CAA section 202(a)(1)'s causation
requirements. Commenters' conclusion still requires the additional logical jump from the
impacts of GHG concentrations to local and regional impacts that may be attributable in
part to changes attributable in part to acidification.
The commenter's attempts to inject harms from oil and gas infrastructure and power
plants demonstrate an important flaw with the interpretation the final action is rejecting.
Setting aside that the sources and activities pointed to by commenters are outside CAA
section 202(a)(1 )'s charge to consider mobile source emissions, the harms cited are not
attributable to GHG exposure. The impacts are attributed to criteria emissions and HAP
emissions. If the commenter's view was correct, the EPA would be able to regulate these
activities out of business using CAA section 202(a)(1) as a pretext.
The commenter's interpretation of the statute is broad enough for the EPA to find that the
regulation of GHGs is appropriate not only because GHGs contribute to air pollution that
endangers public health or welfare within the meaning of the statute, but also because (in
the commenters' view) entities that produce or use fossil fuels are dangerous for other
reasons. It would be inappropriate forthe EPA to consider such far-removed and tenuous
upstream and downstream impacts into its consideration of whether air pollution
endangers public health or welfare. See, e.g., Seven Cnty. Infrastructure Coal. v. Eagle
Cnty., 605 U.S. 168,188 (2025) (concluding that there was no "reasonably close causal
relationship" between an 88-mile railroad project designed to transport oil subject to
Surface Transportation Board NEPA review and the environmental effects of separate oil
drilling and oil refining projects that may result from approving the railroad).
Comments asserting local or regional impacts from methane do not undercut the EPA's
position either. First, the EPA is still required to regulate methane in particular ways, which
cuts against the Endangerment Finding's reading of CAA section 202(a)(1).
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Second, the issue cited by commenters is consistent with our interpretation here. That is,
CAA section 202(a)(1) does not authorize regulation in response to global climate change
concerns, but we agree it does authorize regulation in response to air pollution that harms
through local or regional exposure. If methane contributes to ground level ozone, then it
can be regulated as an air pollutant that contributes to air pollution (ozone) that endangers
public health and welfare. But that is not what the Endangerment Findingfound, and that is
not what subsequent regulations have targeted. None of them decoupled methane from
the other GHGs, and the other GHGs do not have this function.
EPA Summary of Comments
Commenters stated that GHGs make indirect contributions to smog formation analogous
to the impacts of other regulated air pollutants that "caus[e] or contribute] to air pollution
that harms health and the environment through exposure (e.g., smog and acid rain)."
Commenters stated that, additionally, section IV of the proposed preamble recognizes that
indirect contribution to smogformation qualifies as endangerment, but it fails to recognize
this threat from GHGs. Commenters stated that NOx and hydrocarbon emissions have both
long been regulated for increasing the concentrations of ground level ozone and PM; these
secondary pollutants are harmful even to people who aren't significantly exposed to the
originally emitted species (Malashock et al., 2022).
Commenters stated that it is well established that GHGs will also lead to increased
exposure to ozone and particulates (Fann et al., 2015; Wilson et al., 2024). Commenters
stated that this effect was included in the 2009 Endangerment Finding, but the connection
between climate change and air pollution exposure related mortality has since been more
rigorously established. Commenters stated that in a review of peer-reviewed literature from
2012-2017, all the included studies that focused on the United States found that climate
change would increase ozone and PM related mortality (Orru et al., 2017).
EPA Response
The EPA disagrees that potential indirect contributions from GHGs to other regulated air
pollutants is sufficient to meet CAA section 202(a)(1 )'s local or regional harms
requirement. Commenters concede these effects are even more indirect than those relied
upon in the Endangerment Finding and thus are even harder to have a causal relationship.
Air pollutants that contribute to air pollution in the form of ozone can be regulated as such
under our interpretation - that isn't what the Endangerment Finding and subsequent
regulations have done, including because they are primarily concerned with C02
emissions.
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Commenters also seem to suggest that climate change is projected to increase exposure
to other pollutants and pollution, perhaps because of higher temperatures or
displacement of existing human settlement patterns. As above, those assertions involve an
even longer causal chain than the Endangerment Finding. Any such harm would not result
from "air pollution" in the form of local or regional exposure to GHGs; it is an additional
causal step added on to the global climate change theory of CAA section 202(a)(1). As
discussed elsewhere in this document, it would be inappropriate forthe EPA to consider
such an attenuated theory of causation.
EPA Summary of Comments
Commenters stated that there is no need to insert an additional "cause and contribute" to
reach GHGs since the statute already uses the terms "endanger" and "welfare."
Commenters stated that the language that Congress enacted in CAA section 202 plainly
provides the requisite authorization to regulate GHGs based on their climate change
effects; the second "cause or contribute" is unnecessary where Congress employed the
precautionary term "endanger" and, as described above, the broad term "welfare."
EPA Response
The EPA disagrees with this comment. As discussed in more detail elsewhere in the RTC,
impacts based on the global climate change theory are not encompassed by either CAA
section 202(a)(1 )'s reference to "welfare" or the precautionary principle based on the
section's use of endanger. Regarding the former, the EPA's best reading of the statute limits
welfare to local and regional effects based on exposure. As to the latter, the nature of the
harms described by the global climate change theory are beyond the causal scope of the
precautionary principle due to the inherent difference in kind between GHGs and, for
example, the named air pollutants under CAA section 202.
EPA Summary of Comments
Commenters stated that if the EPA's proposed reading of CAA section 202(a)(1) requiring an
additional insertion of "cause and contribute" to reach GHGs were true, it would limit the
regulation of other CAA pollutants. Commenters stated that it is unclear why the EPA's
assertion that regulating GHG emissions requires use of "cause or contribute" twice would
apply any differently to any other pollutant. Commenters pointed to, as an example,
emissions of NOx, which commenters asserted are explicitly referenced in CAA section
202, and which "cause, or contribute to" endangerment through multiple channels, in
interaction with multiple pollutants, substances, and atmospheric conditions.
EPA Response
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This argument supports the EPA's position in the proposed and final action because the
Agency has regulated NOx emissions under CAA section 202(a)(1) consistent with other
specific provisions in section 202 authorizing and requiring regulation of NOx and other
identified pollutants. NOx is a pollutant that causes harm through local and regional
exposure.
2.1.1.1.4 Background Principles of Causation and Proximate Cause and
Their Effect on the Scope of CAA section 202(a)
EPA Summary of Comments
Commenters stated that proximate cause considerations do not inform the meaning of
"cause" or "contribute" within CAA section 202(a). Commenters stated that the EPA's
argument fails because the omission of any modifier before "contributes to" in CAA section
202(a) indicates that Congress intended to adopt the ordinary meaning of the word
"contribute," not a higher contributory requirement, let alone a judge-made formulation of
proximate cause. Commenters stated that when Congress uses "less legalistic language"
in lieu of "the words 'proximate cause,'" "there is little reason for courts to hark back to
stock, judge-made proximate-cause formulations." CSXTransp., Inc. v. McBride, 564 U.S.
685,702-03 (2011).
EPA Response
The commenter's argument is not consistent with the Supreme Court's proximate cause
case law, which reads principles into general language and terms like "cause" and
"contribute." The proposal and final action cite a number of cases readingthese principles
into a broad variety of statutes - Lexmark indicated that it is a general rule.
Specifically regarding commenters'views on CSX Transportation, commenters cite to a
portion of the opinion that is not the majority opinion. Justice Ginsberg delivered the
opinion of the Court "except as to Part lll-A." 564 U.S. at 688. Part lll-A includes the quoted
language at 564 U.S. at 702-03. For Part lll-A, the Court split 4 to 4; Justice Thomas joined
all but Part lll-A. CSX addressed a different issue under a different statute. In CSX, the
Supreme Court found that the Federal Employers' Liability Act (FELA) does not incorporate
"proximate cause" standards and instead informs juries "that a defendant railroad caused
or contributed to a plaintiff employee's injury if the railroad's negligence played any part in
bringing about the injury." 564 U.S. at 688 (emphasis added).6 The FELA provision at issue,
45 U.S.C. § 51, renders railroads liable for employees' injuries or deaths "resulting in whole
6 The actual holding in Part lll-B is that "it is not error in a FELA case to refuse a charge embracing stock
proximate cause terminology." 564 U.S. at 705.
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or in part from [the railroad's] negligence." 564 U.S. at 688. The majority reasoned that, in
light of the statute's "in whole or in part" language and Congress' "humanitarian" and
"remedial goal[s]" in enacting the statute, FELA's causation standard is "relaxed"
compared to that applicable in common-law tort litigation. Id. at 686, 692. This reasoning
does not apply to the EPA's regulatory authorities under CAA section 202(a)(1), which
provides no basis for an "any part" theory of causation and was not, like the FELA, intended
to remedy "harsh and technical" State common law rules that had made recovery difficult
or impossible for injured railroad workers. See id. at 695. Notably, Justice Roberts wrote in
dissent Q'oined by Justices Scalia, Kennedy, and Alito) that the majority's rejection of
proximate cause under the FELA, in favor of the "any part... in producing the injury" test,
was unsupported by the statute's text and longstanding judicial precedent and would lead
to a "boundless theory of liability." 564 U.S. at 705-720. A number of Supreme Court
decisions post-dating CSX support the EPA's conclusion that CAA section 202(a)(1)'s
"cause or contribute" language is best read consistent with longstanding principles of
causation and proximate cause.7
Lexmark, which involved a statutory cause of action, was decided in 2014 after CSX
Transportation: "[W]e generally presume that a statutory cause of action is limited to
plaintiffs whose injuries are proximately caused by violations of the statute. For centuries,
it has been 'a well established principle of [the common] law, that in all cases of loss, we
are to attribute it to the proximate cause, and not to any remote cause.' That venerable
principle reflects the reality that 'the judicial remedy cannot encompass every conceivable
harm that can be traced to alleged wrongdoing.' Congress, we assume, is familiar with the
common-law rule and does not mean to displace it sub silentio. We have thus construed
federal causes of action in a variety of contexts to incorporate a requirement of proximate
causation." Lexmark Int'l, Inc. v. Static Control Components, Inc., 572 U.S. 118,132 (2014)
(internal citations omitted).
EPA Summary of Comments
Commenters stated that the EPA does not acknowledge or address/distinguish from prior
caselaw relevant to this argument. Commenters stated that the failure to do so ignores an
important aspect of the problem. Commenters stated that the Supreme Court in
Massachusetts ruled that plaintiffs had established standing, rejecting similar arguments
that the chain of causation between vehicle GHG emissions and the resulting harm was
inadequate. Massachusetts, 549 U.S. at 524-25, 526. Commenters stated that the D.C.
Circuit has already rejected similar attempts to impose causation principles on
7 See, e.g., Bankof Am. Corp. v. City of Miami, 581 U.S. 189, 201 (2017); Lexmark Int'l, Inc. v. Static Control
Components, Inc., 572 U.S. 118,132 (2014); Univ. of Tex. Sw. Med. Ctr. v. Nassar, 570 U.S. 338, 347 (2013).
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contribution tests. See, e.g., Catawba Cnty. v. EPA, 571 F.3d 20, 38-39 (D.C. Cir. 2009)
(rejecting arguments under CAA section 107 that "contribute" should mean "strictly cause"
or "necessarily connotes a significant causal relationship" because "contribution may
simply exacerbate a problem rather than cause it" and does not require that "corrective
measures" on contributors' emissions actually "address the problem").
EPA Response
Commenters' references to Massachusetts and D.C. Circuit caselaw are misleading and
not applicable to the causation principles explained in the proposed and final action. The
Article III standing inquiry is not the same as proximate cause; for standing, one assumes
the merits of the claim and asks whether there is a cognizable injury traceable to the
challenged action and redressable. In Massachusetts, that would have meant assuming
petitioners were correct that the EPA could regulate GHGs under CAA section 202(a)(1) and
asking whether the resulting injury (climate change) was traceable to the challenged action
(not regulating under CAA section 202(a)(1)).
Catawba County is consistent with our reasoning too. The EPA is not requiring a "strictly
cause" or "significant" causation threshold. Instead, we argue that "contribute" itself
imposes some proximate cause limitation on the relevant causal chain, particularly read in
context with "air pollution" and "reasonably be anticipated to endanger."
On its own terms, the D.C. Circuit in Catawba County held that "contribute" does not
require showing that the contributing thing strictly caused the problem or that the statute
would allow the EPA, based on finding contribution, to totally eliminate the problem. It is
enough to "exacerbate" the problem. But the court did not opine on the floor of what it
means to contribute, and here we are saying that "contribute" is not best read to mean any
possible kind or length of chain of causation satisfies the statutory standard.
In addition to this aspect of causation, as the EPA has discussed elsewhere in the RTC
regarding the degree of contribution, the D.C. Circuit has also recognized that there is a de
minimis floor to the concept of "contribute." See Ethyl Corp. v. EPA, 541 F.2d 1 (D.C. Cir.
1976); Alabama Power v. Costle, 636 F.2d 323 (D.C. Cir. 1979).
We note also that Catawba Countywas a Chevron case - the court held that the statute did
not unambiguously require reading "significant" or "strictly cause" into the word
"contribute" at Step One. Then it rejected arguments that the EPA's interpretation was
unreasonable at Step Two. 571 F.3d at 39 (Step One), 40 (Step Two). Given this case was
under CAA section 107, that reasoning certainly does not settle the best reading for CAA
section 202(a)(1) today under Loper Bright.
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EPA Summary of Comments
Commenters stated that the EPA fails to identify any endangerment finding that was made
prior to 2009 (much less a consistent practice) that was grounded in proximate causation
principles as opposed to an application of the plain meaning of "contribute." Commenters
cited to a couple of examples. Commenters stated that, in the CAA section 111 context,
the EPA has repeatedly made significant contribution findings forfar smaller contributions
than those of new vehicles to GHGs. Commenters stated that, in the vehicle context, the
EPA believed (and the court agreed) that the EPA was authorized to issue standards for PM
from light-duty diesel vehicles in 1980, even though the contribution of heavy-duty diesel
vehicles vastly exceeded their contribution, under CAA section 202(a)(1). See Standard for
Emission of Particulate Regulation for Diesel-Fueled Light-Duty Vehicles and Light-Duty
Trucks, 45 FR 14496 (Mar. 5, 1980); Nat. Res. Def. Council v. EPA, 655 F.2d 318, 324-27
(D.C. Cir. 1981).
EPA Response
As explained elsewhere in the RTC, the EPA is not resting on a degree of contribution theory
for the argument at issue here; we are saying that there is a difference in kind. Problems
with the Endangerment Finding's reasoning as related to the degree of contribution are
discussed elsewhere in the proposed and final action as well as elsewhere in this RTC. The
problem addressed under our causation analysis here is the length of the causal chain
required to get there, which informs the meaning of "air pollution" and "reasonably be
anticipated to endanger."
On its own terms, the example forvehicles cited by commenters is consistent with our
theory- PM emissions from vehicles contribute to PM air pollution, and PM air pollution
endangers public health.
That the EPA relied on CAA section 202(a)(3)(A)(iii) in the 1980 rule (which the court later
found was incomplete, because it should have also relied on 202(a)(i)) supports our
position, as it shows that when Congress wanted the EPA to regulate in particular ways
under CAA section 202, it added language specifying what it wanted.
EPA Summary of Comments
Commenters stated that GHG pollution would meet the EPA's proposed proximate
causation standard. Commenters stated that even if proximate cause were the standard,
the question would be whether it is foreseeable that GHG pollution will contribute to
climate change and have harmful effects and it is eminently clear that GHG pollution
meets this standard. Commenters stated that proximate cause precludes liability only
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where the causal link "is so attenuated that the consequence is more aptly described as
mere fortuity." Paroline v. United States, 572 U.S. 434, 445 (2014).
EPA Response
The EPA disagrees with this understanding on its own terms and more generally. "More
aptly described" does not mean the adverse event is indeed a mere fortuity, only that it is
closer to a fortuity than a direct consequence.
As discussed above, Lexmark supports the rule that general principles of proximate
causation apply when reading "cause" and "contribute", and additional cases establish
that these principles do not apply without limit. For example, "contribute" is not best read
to mean any possible chain of causation satisfies the statutory standard. Take City of
Oakland v. Wells Fargo & Co., 14 F.4th 1030 (9th Cir. 2021) (en banc), which supports this
principle. That case interpreted the Fair Housing Act (FHA) to resolve the City of Oakland's
claim that Well Fargo's lending practices caused higher default rates, triggering a chain of
events that decreased city property tax revenue and increased city expenditures. Though
the court acknowledged the wide-ranging economic impacts of Wells Fargo's lending
policies, it declined to treat all of those impacts as relevant under the particular statute. "In
acknowledging that '[t]he housing market is interconnected with economic and social life,'
the Court observed that '[a] violation of the FHA may, therefore, 'be expected to cause
ripples of harm to flow' far beyond the defendant's misconduct.' Nonetheless, the Court
limited the legal consequences of those ripples: 'Nothing in the statute suggests that
Congress intended to provide a remedy wherever those ripples travel.'" Id. at 1032 (internal
citations omitted).
Additionally, as discussed elsewhere in this RTC, the D.C. Circuit has recognized that there
is a de minimis floor to the concept of "contribute." See Ethyl Corp. v. EPA, 541 F.2d 1 (D.C.
Cir. 1976) and Alabama Power v. Costle, 636 F.2d 323 (D.C. Cir. 1979). The EPA is applying
these concepts to inform its best reading, not in isolation, but as part of an integrated
interpretation of "contribute" together with "air pollution" and "reasonably be anticipated
to endanger," which signal an outer legal limit on the authority to anticipate dangers to
public health and welfare from air pollution.
EPA Summary of Comments
Commenters stated that the EPA's causation argument is circular and lacks explanatory
detail. Commenters stated that the EPA's argument begs the question what might
constitute "proximate cause" under the CAA. Commenters stated that, in the common law,
"proximate cause" is a legal construct that often includes concepts of "but-for causation"
and a foreseeable class of victims within a "zone of danger." Commenters stated that to
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conceive of "cause" as being understood with reference to "proximate cause" in the
context of the CAA is circular in that it would mean the "cause" legally required by the CAA.
EPA Response
The EPA disagrees. Proximate cause is necessarily about line drawing. The proposed and
final action plainly draw the line between emissions that contribute to air pollution with
adverse impacts from regional and local exposure on one hand and air pollutant emissions
that contribute to global climate change concerns that contribute to regional and local
adverse impacts on the other. The Endangerment Finding relied on too attenuated of a
causal chain in embracingthe global climate change concern theory of CAA section
202(a)(1). Commenters overstate their case that the EPA's line drawing "begs the question
what might constitute 'proximate cause' under the CAA." Air pollution that endangers
public health and welfare through local or regional exposure undoubtedly satisfies the
causal requirement.
The EPA's view acknowledges that proximate causation may require considerations related
to both factual causation and legal causation. The concept of factual causation involves
tracingthe links of a causal chain to, for example, establish an unbroken causal connection
between an action and a harm; legal causation tells one how many links are appropriate in
the context of the statutory provision at issue. In other words, merely establishing a lengthy
causal chain is not enough to meet proximate causation requirements, especially where
the linkage between the action and the harm may be especially attenuated. City of Oakland
v. Wells Fargo & Co., 14 F.4th 1030 (9th Cir. 2021) (en banc) illustrates this principle. That
case interpreted the Fair Housing Act (FHA) to resolve the City of Oakland's claim that Well
Fargo's lending practices caused higher default rates, triggering a chain of events that
decreased city property tax revenue and increased city expenditures. Though the court
acknowledged the wide-ranging economic impacts of Wells Fargo's lending policies, it
declined to treat all of those impacts as relevant under the particular statute. "In
acknowledging that '[t]he housing market is interconnected with economic and social life,'
the Court observed that '[a] violation of the FHA may, therefore, 'be expected to cause
ripples of harm to flow' far beyond the defendant's misconduct.' Nonetheless, the Court
limited the legal consequences of those ripples: 'Nothing in the statute suggests that
Congress intended to provide a remedy wherever those ripples travel.'" Id. at 1032 (internal
citations omitted).
EPA Summary of Comments
Commenters stated that the notion that an indirect action can cause demonstrable harm is
common sense and understood by anyone, analogizing that rolling up the car windows on a
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hot day can kill a child left inside the car, but no reasonable person would complain that
rolling up the windows is too "indirect" to be considered a cause of the harm to the child.
Commenters stated that, here too, the proposal appears to acknowledge that "indirect"
pollutants can harm health and are rightly regulated by the CAA.
EPA Response
The EPA disagrees with the commenter's characterization of our best reading of CAA
section 202(a)(1). Our view does not categorically reject "indirect" effects and accounts for
a broad range of harms for air pollution that adversely impacts public health and welfare
through local or regional exposure. What we reject is that the global climate change theory
of harm is encompassed within the best reading of CAA section 202(a)(1).
EPA Summary of Comments
Commenters stated that a scientifically erroneous component of the proposal's argument
is that the causal chain linking emissions to impacts is too uncertain and complex to be
trustworthy. Commenters argued the causal chain can be understood and simply
explained with three "well-established" scientific facts: (1) global warming is linear in
cumulative emissions; (2) local warming is roughly linear in global warming; and (3) climate
impacts in a particular location are roughly linear in local warming.
EPA Response
The EPA disagrees with the commenter's characterization of the causal chain required by
the global climate change theory. The principles described by commenters do not fully
reflect the causal steps between the emission of an air pollutant (here GHGs), and the
harms to public health and welfare asserted under the global climate change theory.
Instead, they collapse multiple steps to obscure the true complexity of the causal chain.
For example, the statement that "[gjlobal warming is linear in cumulative emissions" is
dependent on multiple steps - local emission of the pollutant, diffusion of the pollutant
into the atmosphere contributing to a global concentration, and then the interaction of
multiple, complex atmospheric mechanisms that commenters shorthand with a
mathematical relationship.
2.1.1.1.5 The Necessity of EPA's Best Reading to Avoid Absurd Results
EPA Summary of Comments
Commenters stated that the Endangerment Finding did not require the EPA to regulate
water vapor as a GHG. Commenters stated that the EPA squarely addressed this specific
issue in the Endangerment Finding and explained why water vapor was not required to be
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and was not included under its then-interpretation of CAA section 202(a). Co mm enters
stated that the proposal does not acknowledge, much less refute, the EPA's prior
conclusions. See, e.g., 7A FR 66520 (Dec. 15, 2009) ("Direct anthropogenic emissions of
water vapor, in general, have a negligible effect and are thus not considered a primary
driver of human-induced climate change."). Commenters stated that this issue was also
raised in Massachusetts. See Br. Of Resp. C02 Litig. Grp., supra note 146 at 9 & n.7 ("If
anything enteringthe ambient air is considered an air pollutant, then even a substance that
is beneficialto humans, like oxygen or watervapor, is treated as if it were contaminating the
air.")
EPA Response
Commenters are correct that the EPA discussed whether water vapor could be regulated
as a GHG under the 2009 Endangerment Finding framework and declined to include water
vapor within the definition of air pollution. 74 Fed. Reg. 66520 (Dec. 15, 2009). The EPA
reasoned that direct anthropogenic emissions of water vapor "have a negligible effect and
are not considered a primary driver of human-induced climate change." The Endangerment
Finding went on to note that the Agency "plans to further evaluate the issues of emissions
of water that are implicated in the formation of contrails and also changes in water vapor
due to local irrigation." Id. Id. However, this distinction is untenable as a matter of logic. The
proposal and final action do not refute the factual record that the EPA made a prior finding,
they draw a different conclusion. Our analysis shows that, logically, the statutory
interpretation adopted in the Endangerment Finding applies just as well to watervapor as it
does to the GHGs analyzed. The point is not that the EPA has regulated watervapor, but
that this interpretation means that it could.
The Supreme Court did not address this argument in Massachusetts. It is improper to infer
that the Court disagreed with all counterarguments (or agreed with all arguments in favor of
reversal) that it did not address expressly.
EPA Summary of Comments
Commenters stated that an actual, rather than a hypothetical, nondelegation issue is
needed to invoke constitutional avoidance. The comment states, without additional
citations to support: "The Proposal hypothesizes the regulation of water vapor as an
'absurd result[]' that would convert section 202(a)(1) 'into a roaming license to prescribe...
standards.' [citing 90 FR at 36,301, internal quotation marks omitted]... But a 'potential'
rather than actual nondelegation problem would not warrant invocation of constitutional
avoidance."
EPA Response
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The EPA disagrees with this comment. Here, the EPA's best reading of the statute is that it
does not confer to the EPA the discretion to regulate GHGs under the global climate
change theory. Constitutional avoidance is one reason to reach that conclusion; even if the
statute were ambiguous, the canon tells us to err on the side of avoiding constitutional
concerns. See RTC section 2.1.2.4.1 for a more detailed discussion of this issue.
EPA Summary of Comments
Commenters stated that applying CAA section 202(a)(1) to GHGs does not pose a
nondelegation problem. The comment states: "Further, requiring EPA to regulate vehicular
pollution mediated through other means than 'local or regional exposure' does not leave
section 202(a)(1) bereft of an intelligible principle. It just means the statute supplies a
principle-regulate all types of air pollution that meet the other 'guideposts" and
"boundaries' explicitly set out in section 202(a)(1) and informed by the Clean Air Act's
health-protective purpose."
EPA Response
The EPA disagrees with this comment. The nondelegation problem here relates to the
scope of regulation - if Congress intentionally wrote CAA section 202(a)(1) as a roaming
license to identify and respond to problems, then Congress has not set out an intelligible
principle and fully delegated the legislative authority over vehicle emissions to the EPA. The
statutory interpretation relied on by the Endangerment Finding leaves CAA section
202(a)(1) vulnerable to that interpretation. As such, avoiding that potential result is another
reason to disfavorthe approach used in the Endangerment Finding. See additional
response on this issue in RTC section 2.1.2.4.1.
2.1.1.1.6 EPA's Longstanding Practice Prior to 2009
EPA Summary of Comments
Commenters stated that the proposal's assertions about the EPA's prior longstanding
practice are not true. Commenters stated that "executive history" is not an authority; an
agency is not permitted to rescind a rule merely based on its own previous interpretation of
a statute. Commenters went on to discuss examples that commenters stated supported
their first assertion and that other pollutants regulation has long included recognition that
those pollutants have indirect and non-exposure-based effects on human health or
welfare. For one example commenters stated that in 2000, the EPA issued a regulation
under CAA section 202 to control NOx emissions and highlighted they "produce a
substantial rise of nitrogen levels in surface waters," which in turn "result[s] in excess algae
and plant growth... [that] can cause numerous adverse ecological effects and economic
impacts," in which commenters asserted that the EPA recognized that impacts on fish
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would indirectly harm human welfare. For another example, commenters stated that the
EPA has also recognized global impacts in assessing endangerment findings for non-GHG
rules under CAA section 202, including under various CAA provisions, the EPA has found
that global air pollution impacts cause or contribute to endangerment of public health or
welfare.
Commenters also cited to statements they assert claim EPA authority includes GHGs. For
example, commenters stated that in 1998, the EPA's General Counsel Jonathan Cannon
prepared a legal opinion (the "1998 Memo") concluding that "C02 emissions are within the
scope of EPA's authority to regulate," and Cannon's successor, Gary Guzy, later confirmed
that interpretation in remarks to Congress.
EPA Response
We disagree with commenters based on our reasoning explained in RTC section 2.1.2.1.2.
We are not saying our prior regulations and the view they reflect authorizes rescission; this
comment is difficult to understand, as the Endangerment Finding is itself a prior action that
reflects a view, so by the same token we should not be bound by the Endangerment
Finding. Rather, we are using regulatory history dating back to the enactment of the
relevant language to show a consistent practice that is valid evidence of the best reading of
the statute. See FTC v. Bunte Brothers, Inc., 312 U. S. 349, 352 (1941) ("just as established
practice may shed light on the extent of power conveyed by general statutory language, so
the want of assertion of power by those who presumably would be alert to exercise it, is
equally significant in determining whether such power was actually conferred").
The examples pointed to by commenters do not refute the EPA's position. Direct
acidification from NOx emissions is consistent with the EPA's best reading of CAA section
202(a)(1), which requires harm to public health and welfare from local or regional exposure
effects. It does not support the Endangerment Finding's global climate change theory. The
other examples are not as specifically raised but likely suffer from a combination of defects
by mischaracterizing at least one of the following as consistent with the Endangerment
Finding's global climate change theory: the transportation of substances with local or
regional exposure-based effects over long distances or Congress's use of detailed, tailored
language in other parts of the CAA to address global or regional issues. The 1998 Memo
does not contradict the history presented in the proposed and final actions. Regulatory
examples are the authoritative and relevant authority for the EPA's analysis of CAA section
202(a)(1); memos like this are not. We argued in the proposal and final action that the EPA
had never finalized such an approach before, and that is true. The EPA later repudiated the
1998 Memo.
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2.1.1.1.7 The Effect of Massachusetts v. EPA
EPA Summary of Comments
Commenters stated that the proposal underreads Massachusetts. Commenters stated
that the EPA's holding that CAA section 202(a) is best read as authorizing the Agency to
regulate only those air pollutant emissions that cause or contribute to air pollution that
endangers public health or welfare through local or regional exposure is foreclosed by
Massachusetts. Commenters stated that the Court's ruling in Massachusetts is dispositive
on the question of the EPA's authority to regulate GHGs, including from new motor
vehicles, in the event that the EPA forms a "judgment" that such emissions contribute to
climate change. Commenters stated that the Court's statement that it "need not and
do[es] not reach the question whether on remand EPA must make an endangerment
finding" means that the EPA retains authority to determine whether the statutory standard
for regulation is satisfied, not whether GHGs qualify as air pollutants in the first place
under CAA section 202(a). More specifically, some commenters discussed certain
examples, asserting they supported their arguments. For one example, commenters stated
that the very first question the Supreme Court answered on the merits in Massachusetts v.
EPA was "whether § 202(a)(1) of the Clean Air Act authorizes EPA to regulate greenhouse
gas emissions from new motor vehicles in the event that it forms a 'judgment' that such
emissions contribute to climate change." Massachusetts v. EPA, 549 U.S. 497, 528 (2007).
Commenters stated that the Court had "little trouble concluding that it does." Id.; see also
id. at 529 n.26 (rejecting the dissent's application of Chevron deference because the text is
clear).
For another example, commenters stated that the Court rejected any suggestion that
distinctions in the nature of pollution were relevant to the authority question.
Commenters stated that, while acknowledging the EPA's suggestion that "Congress
designed the original Clean Air Act to address local air pollutants rather than a substance
that 'is fairly consistent in its concentration throughout the world's atmosphere'" {id. at
512, quoting the EPA's denial of the petition for rulemaking), the Court rejected the
relevance of such potential distinctions. Commenters stated that the Court instead stated
that 1) the EPA's interpretation (distinguishing GHGs because they permeate global
atmosphere rather than limited area near surface) was "a plainly unreasonable reading of a
sweeping statutory provision designed to capture 'any physical, chemical... substance or
matter which is emitted into or otherwise enters the ambient air," 2) whether or not
Congress anticipated a problem like climate change, "[t]he broad language of § 202(a)(1)
reflects an intentional effort to confer the flexibility necessary to forestall [the provision's]
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obsolescence," id. at 532, and 3) the definition of "welfare" "is also defined broadly: among
other things, it includes 'effects on ... weather... and climate.'" Id. at 506.
See additional response related
EPA Response
The EPA disagrees with commenters' assertion that Massachusetts held broadly that CAA
section 202(a)(1) authorizes the regulation of GHGs in response to global climate change
concerns. The Court did not have before it that broad question, nor was the EPA's
application of the statute in the Endangerment Finding before the Court. Rather, the Court
was presented with the reasons that the EPA cited in denying the petition for rulemaking at
issue. For example, that is why the Court concluded the paragraph quoted in the comment
summary above by reciting the EPA's position that the Act-wide definition of "air pollutant"
does not encompass C02. 549 U.S. at 528. (As for the commenter's reference to n.26, that
discussion was limited to the "air pollutant" definition and doesn't support commenter's
broad reading of the opinion. See also this final action's discussion of how the definition of
"air pollutant" at issue in n.26 in Massachusetts, including the phrase "ambient air," is very
different from our argument in this final action about "air pollution" and the evidence
marshalled for that understanding. We also note that this footnote is rebutting an argument
made in the dissent in Massachusetts and reiterate that judicial opinions must be read in
context).
Note that court opinions, even Supreme Court opinions, are not to be read like statutes.
See Turkiye Halk Bankasi A.S. v. United States, 598 U.S. 264, 278 (2023) ("This Court has
often admonished that general language in judicial opinions should be read as referring in
context to circumstances similar to the circumstances then before the Court and not
referring to quite different circumstances that the Court was not then considering.")
(internal citations omitted); Reiterv. Sonotone Corp., 442 U.S. 330, 341 (1979) ("the
language of an opinion is not always to be parsed as though we were dealing with the
language of a statute.");."); see also Zenith Radio Corp. v. United States, 437 U.S. 443, 462
(1978) (explaining that a prior Court opinion did not address the arguments or particular
situation presented in the new case); Cohens v. Virginia, 19 U.S. (6 Wheat.) 264, 399-400
(1821) ("It is a maxim not to be disregarded, that general expressions, in every opinion, are
to be taken in connection with the case in which those expressions are used. If they go
beyond the case, they may be respected, but ought not to control the judgment in a
subsequent suit when the very point is presented for decision. The reason of this maxim is
obvious. The question actually before the Court is investigated with care, and considered in
its full extent. Other principles which may serve to illustrate it, are considered in their
relation to the case decided, but their possible bearing on all other cases is seldom
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completely investigated.") (distinguishing"the single question before the Court" in Marbury
v. Madison).
In several places in the Massachusetts opinion, the Court uses language of "authority" to
refer generally to the statute. 549 U.S. at 528, 532. In context, the Court was applying its
holding that the EPA erred in concluding that the Act-wide definition of "air pollutant"
excludes C02. The Court elsewhere recognized that although it could review denials of
petitions for rulemakings, "such review is extremely limited and highly deferential." 549 U.S.
at 527-28. Immediately after, the Court framed its review as limited to the two reasons the
EPA offered for denying the petitions - C02 is not an "air pollutant" and policy reasons. Id.
at 528.
The final action here is entirely consistent with the Court's two holdings in Massachusetts.
As the Court noted in UARG, that certain gases are encompassed within the Act-wide
definition does not mean they can be regulated under any specific regulatory provision,
read in context. Gases may be within the CAA but outside the scope of particular
provisions. Furthermore, courts can, and often do, consider the same regulatory issue in
multiple cases that address the reasoning and arguments in front of them each time. It can
take multiple rounds to get at all of the possible legal issues, including the best reading of
various aspects of a provision. A classic administrative law example comes from the
Chenery cases. In Cheneryl, the Supreme Court set aside an SEC order that could not be
sustained on the explanation the SEC had given during its administrative proceeding. SEC
v. Chenery Corp., 318 U.S. 80 (1943). Following proceedings on remand, the case came
back before the Supreme Court in Chenery II, and the Court upheld the SEC's order, which
it now found to be based on lawful grounds available under SEC's enabling act. SEC v.
Chenery Corp., 332 U.S. 194 (1947). A court's disposition of one case does not mean the
same result is necessitated when the same general subject matter or the same or similar
parties come before the courts again; it depends on what specific issue is in dispute. Cf.
New Hampshire v. Maine, 532 U.S. 742, 748-49 (2001) ("Issue preclusion generally refers to
the effect of a prior judgment in foreclosing successive litigation of an issue of fact or law
actually litigated and resolved in a valid court determination essential to the prior judgment
...") (emphasis added). More recent examples of courts reaching different results when
faced with the same or similar agency actions are of course available. The D.C. Circuit
generally upheld the EPA's 1998 NOxSIP Call implementing CAA section 110(a)(2)(D)(i)(l),
Michigan v. EPA, 213 F.3d 663 (D.C. Cir. 2000), but found substantial flaws in the 2005
Clean Air Interstate Rule, a similar program implementing the same statutory provision,
North Carolina v. EPA, 531 F.3d 896 (D.C. Cir. 2008). The court did not overturn Michigan in
North Carolina; rather, the issues raised by the parties against the latter were different than
the issues raised against the former. Beyond holding that GHGs are "air pollutants" and
that non-statutory policy reasons are out as to the finding aspect of CAA section 202(a)(1),
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the Court in Massachusetts did not constrain what the EPA could say or do on remand. As
detailed in the preamble, this final action is now reaching conclusions about the mismatch
between the contribution and the "air pollution," the mismatch of the "air pollution" with
respect to all other air pollution addressed in the CAA, and the futility problems.
Inln the petition denial ("2003 Denial," 68 FR 52922, discussed further in this final action's
preamble), the EPA concluded that it was unreasonable to conclude that the CAA provides
the Agency with authority to address climate change through regulation and that the
definition of "air pollutant" in CAA section 302(g) as used in CAA regulatory provisions
cannot be interpreted to encompass global climate change. 68 FR at 52928. In focusing on
the "air pollutant" Act-wide definition, the EPA cited a broad list of various CAA regulatory
provisions (including sections 108,109,111,112 and 202) that have the commonality of
using the term "air pollutant." Id. The EPA did not attempt, as here, to present the best
reading of the statute as a whole and did not offer interpretations of other statutory terms
in those regulatory provisions. Instead, the EPA took the categorical position that GHGs are
not encompassed within the CAA at all. The EPA's merits brief for Massachusetts similarly
focused on the Act-wide definition of "air pollutants," and the list of the various regulatory
statutory provisions upon which petitioners relied, in arguing the EPA reasonably
determined that GHGs are not air pollutants under the CAA's regulatory provisions, 2006
U.S. S. Ct. Briefs LEXIS 1106, *58.
In many ways, this final action is narrower than the 2003 Denial. We recognize that the
gases grouped together as GHGs may be regulated as air pollutants when appropriate
under a particular regulatory provision. And since then, Congress has provided for specific
ways in which we must regulate particular GHGs (e.g., HFCs and methane through the
methane fee program, albeit that program was revised to a later date (an additional ten
years) in the OBBBA).
Importantly, the Court's bottom-line judgment in Massachusetts was: "We need not and do
not reach the question whether on remand EPA must make an endangerment finding, or
whether policy concerns can inform EPA's actions in the event that it makes such a finding.
[Citing Chevron]. We hold only that EPA must ground its reasons for action or inaction in
the statute." 549 U.S. at 534-35. Here, the Court provided a helpful summation of what the
Court thought it was doing, togetherwith its holding that the denialof the petition is
reviewable in a narrow way.
Regardingthe quote at b.A.1. in the comment summary above, that quote is from the fact
section of the opinion and was included only as a lead up to the EPA's conclusion that
GHGs are not "air pollutants." 549 U.S. at 513. The Court did not return to the issue as a
general matter, and it did not address our primary conclusion in that case that the term "air
pollution" is the relevant limitation.
EPA Summary of Comments
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Commenters stated that Massachusetts, on its own terms, and as understood by courts
since, addressed not just the meaning of the Act-wide definition of "air pollutant," but also
ratified the EPA's authority to regulate GHG emissions from new motor vehicles as air
pollutants under CAA section 202(a). Commenters stated that the EPA is wrong to suggest
that "harmonizing" UARG, West Virgina, and Loper Bright would have the effect of
narrowing the meaning of Massachusetts; if they bear on Massachusetts at all, it is to
affirm, not cast doubt on, that case's conclusion. More specifically, some commenters
cited to examples from case law which they asserted supported their arguments.
Regarding UARG, commenters stated that "In 2007, the Court held that Title II of the Act
authorized EPA to regulate greenhouse gas emissions from new motor vehicles if the
Agency formed a judgment that such emissions contribute to climate change." Util. Air
Regul. Grp. v. EPA, 573 U.S. 302, 310 (2014) (cleaned up). Commenters stated that the
proposal states that the Agency '"may not treat greenhouse gases as a pollutant' in the
[Prevention of Significant Deterioration] PSD and Title V contexts." Commenters stated that
what the Court fully said was: "Specifically, the Agency may not treat greenhouse gases as
a pollutant for purposes of defining a 'major emitting facility' (or a 'modification' thereof) in
the PSD context or a 'major source' in the Title V context... EPA may, however, continue to
treat greenhouse gases as a 'pollutant subject to regulation under this chapter' for
purposes of requiring BACT for'anyway' sources." Commenters stated that, in other words,
in UARG, the Court upheld the EPA's rule requiring sources that were otherwise subject to
the PSD program {i.e., because they met the definition of "major emitting facility" under
CAA section 169(1) due to the magnitude of their potential emissions of "any air pollutant"
other than GHGs) to comply with the "best available control technology" requirements with
respect to their GHG emissions.
Regarding West Virginia, commenters stated that while rejecting the EPA's specific
regulatory choices, the Court affirmed that the EPA has authority to regulate GHGs from
power plant sources under the CAA, see id. at 730 (referencing the Court's earlier holding in
Am. Elec. Power Co. v. Connecticut that CAA section 111 applies to C02 emissions from
power plants, which itself was based on the fact that Massachusetts allowed regulation of
GHGs, 564 U.S. 410, 424 (2011)).
Commenters stated that under Loper Bright, the EPA is not empowered to change the
meaning of "pollutant" in the CAA to suit its policy preferences, even assuming, arguendo,
that its new interpretation might have been upheld under previous precedents as "a
permissible construction of the statute." Id. at 397. Commenters stated that, rather, the
EPA's interpretation here must reflect the "best" meaning of that term, which, as discussed
above, was already decided in Massachusetts. Commenters stated that Loper Bright's new
standard that "courts must exercise their independent judgment in deciding whether an
agency has acted within its statutory authority," is exactly the analysis made in
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Massachusetts. Commenters stated that framing Loper Bright as an intervening legal
development that demands the reconsideration of the Endangerment Finding is fiction.
Regarding Coalition for Responsible Regulation, commenters stated that the proposal
ignores Coalition for Responsible Regulation, which upheld both the Endangerment Finding
and the Tailpipe Rule, and did so while rejecting many of the same arguments that the EPA
is now making. Commenters stated that, for example, the D.C. Circuit held that
Massachusetts foreclosed the argument that because GHGs do not "cause elevated
ground-level concentrations in ambient air people breathe," the EPA should have excluded
GHGs from its interpretation of "any air pollutant."
Commenters also cited to Concerned Household Electricity Consumers Council v. EPA,
and FAIR Energy Foundation v. EPA, No. 23-418, cert denied (Dec. 11, 2023) as cases where
the EPA's authority under Massachusetts has been upheld. Commenters also stated that
the Supreme Court "notably" declined to grant certiorari on questions concerningthe
validity of the 2009 Endangerment Finding. See Chamber of Com. v. EPA, 571 U.S. 951
(2013) (granting petition for a writ of certiorari only as to a question concerning the
triggering of statutory source permitting requirements and denying as to questions
concerningthe validity of the EPA's Endangerment Finding); Texas v. EPA, 571 U.S. 951
(2013) (same); Southeastern Legal Found, v. EPA, 571 U.S. 951 (2013) (same); Virginia v.
EPA, 571 U.S. 951 (2013) (denying petition for a writ of certiorari as to questions concerning
the EPA's Endangerment Finding); Pacific Legal Found, v. EPA, 571 U.S. 951 (2013) (same);
Coal, for Responsible Regul., Inc. v. EPA, 571 U.S. 951 (2013) (same). Commenters stated
that amongst those denials, the Court specifically denied a request that it consider
whether to overrule Massachusetts. Texas v. EPA, 571 U.S. 951 (2013).
EPA Response
See our discussion in the preamble_and our response above in this section on
Massachusetts, including regarding harmonization of Massachusetts and subsequent
caselaw. Case law evolves and develops over time, and agencies must thus consider how
courts regularly build upon prior holdings and legal principles over time. In this action, we
recognize that the Supreme Court has repeatedly vacated EPA actions in the years since
Massachusetts, and faithfully applying the law means acting consistently with the cases as
a whole. We disagree with commenters' apparent suggestion that Massachusetts is the
final word on the scope of the EPA's authority or principles of statutory interpretation. In
response to the points summarized above from commenters, we also provide more
detailed responses on quoted decisions here.
Regarding UARG, see our response above in this same RTC section regarding
Massachusetts and discussion of UARG in RTC section 2.1.2 regarding MQD. In short, the
Court in UARGwas takingthe underlying Endangerment Finding as a given because the
question wasn't before it, as at that stage, petitioners were not asking the Court to vacate
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the PSD program application on the grounds that the Endangerment Finding and resulting
regulations that made GHGs relevant to permitting were invalid. Regarding the section of
the opinion commenters refer to, the Court was quoting Massachusetts in the background
section of the opinion, and thus the full context of the Court's decision in Massachusetts is
key as we discuss in detail above in this section of the RTC. We also note that the Court
specifically states "if the Agency 'formed a judgment.'". "If" is key in that framing, and thus
nothing in UARG suggests that the EPA could not have formed a "judgment," based in the
statute as Massachusetts requires, that GHGs are not properly regulated under CAA
section 202(a)(1) although they are "air pollutants" within the meaning of the CAA more
broadly.
We also note that the Court, in the next sentence of the opinion, recounts what the EPA did
in response to Massachusetts: "In response to that decision, EPA embarked on a course of
regulation resulting in 'the single largest expansion in the scope of the [CAA] in its history."
573 U.S. at 310. As further discussed in RTC section 2.1.2 regarding UARG and the MQD,
that Court did not view that expansion favorably. Relevant here, the Court rejected that
expansion for purposes of the regulatory provision at issue there, a provision that also uses
the term "air pollutant," after concluding that GHGs did not fit into that provision. We
specifically note that the Court in UARG stated the following in rejecting a reading of
Massachusetts as authorizing GHG regulation wherever the term "air pollutant" appears:
"The statute compelled EPA's [GHG]-inclusive interpretation with respect to neither
the PSD program nor Title V." 573 U.S. at 315.
"The Court of Appeals reasoned byway of a flawed syllogism:
Under Massachusetts, the general, Act-wide definition of "air pollutant" includes
greenhouse gases; the Act requires permits for major emitters of "any air pollutant";
therefore, the Act requires permits for major emitters of greenhouse gases. The
conclusion follows from the premises only if the air pollutants referred to in the
permit-requiring provisions (the minor premise) are the same air pollutants
encompassed by the Act-wide definition as interpreted in Massachusetts (the major
premise). Yet no one—least of all EPA—endorses that proposition, and it is
obviously untenable. The Act-wide definition says that an air pollutant is "any air
pollution agent or combination of such agents, including any physical, chemical,
biological, [or] radioactive... substance or matter which is emitted into or otherwise
enters the ambient air." § 7602(g). In Massachusetts, the Court held that the Act-
wide definition includes GHGs because it is all-encompassing; it "embraces all
airborne compounds of whatever stripe." But where the term "air pollutant" appears
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in the Act's operative provisions, EPA has routinely given it a narrower, context-
appropriate meaning." Id. at 316.
Regarding West Virginia, see discussion of West Virginia in RTC section 2.1.2 regarding the
MQD. In short, this reading is incorrect; West Virginia specifically adopted a much narrower
reading of AEP, and it was overturning the D.C. Circuit's decision in American Lung thatwas
based on reading/AEP to say the question was settled as to mobile and stationary sources.
See also West Virginia, 597 U.S. at 753 (Kagan, J. dissenting) ("Today, the Court strips the
Environmental Protection Agency (EPA) of the power Congress gave it to respond to 'the
most pressing environmental challenge of our time.' Massachusetts v. EPA, 549 U.S. 497
(2007)).
Regarding Loper Bright, this final action is not based on a new interpretation of "air
pollutant;" rather the final action is based on the best reading of the statute (CAA section
202(a)(1)) as discussed more fully throughout the preamble and RTC section 2.1.1.
Regarding Coalition, see our response in RTC section 2.1.1.1.1. As explained there and in
the preamble, this final action is not relying on a new interpretation of "air pollutant" or a
conception of what it means to be in the "ambient air." Rather, the final action is based on
the best reading that the "air pollution" of concern in CAA section 202(a)(1) is that which
endangers health or welfare through local or regional exposure, and that GHGs do not
endanger health or welfare through local or regional exposure, and this is consistent with
Massachusetts and subsequent caselaw including UARG, West Virginia, and Loper Bright.
As further explained in RTC section 2.1.1, the Endangerment Finding had to engage in an
unprecedented causal chain that just does not fit the statutory text, as informed by
context, structure, and regulatory history, as well as the MQD. Thus, our argument here is
different from that in Coalition (which rejected certain arguments presented by petitioners
and relied on a combination of logic since rejected by the Supreme Court and a deferential
posture that doesn't bind us here).
Regarding the cited cases where the Supreme Court declined to grant certiorari, such
actions by the Court do not have legal import on this issue.
EPA Summary of Comments
Commenters stated that legal developments since Massachusetts have shown that GHGs
like C02 are not "air pollutants" under CAA section 302(g). Commenters stated that if the
Supreme Court were to consider this question again, the Court would have every reason to
overrule Massachusetts because it implicates important issues, its reasoning was
unsound, it hasn't proved workable over the last twenty years, and no adverse reliance
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interests exist here. More specifically, some commenters stated the following examples
from caselaw supported their arguments.
Commenters stated that, for example, Justice Alito hinted in 2011 that "interpretation of
the Clean Air Act" was not"correct."/4m. Elec. Power Co. v. Connecticut, 564 U.S. 410, 430
(2011) (Alito, J., concurring in the judgment).
One commenter stated and analyzed how the Court will likely overturn that holding using
the five factors the Court summarized in Dobbs v. Jackson Women's Health Org., 597 U.S.
215,268 (2022).
One commenter stated that the absence of Chevron deference in the post-Loper Bright
world suggests that the Endangerment Finding would most likely not survive judicial review
because now 1) the EPA's authority to enact such broad regulatory power must be
grounded in clear statutory text, and 2) such authority is not clearly delegated to the EPA in
the CAA. Rather, the commenter argued, it's likely that, under Loper Bright, the Court would
have found that the Endangerment Finding contradicts the structure and context of the
CAA and defies its legislative history.
Alternatively, some commenters stated that Massachusetts was simply wrongly decided.
Commenters stated that the decision misreads the CAA by ignoring a crucial portion of the
statutory text. Commenters stated that Justice Scalia's dissent in Massachusetts
addresses head-on the plain meaning of "air pollutant" in the CAA, making clear that
including C02 in the CAA's definition of "air pollutant" cannot be the best reading of the
statute. Commenters stated that Scalia's dissent opines that while GHGs "fit within the
second half" of the "air pollutant" definition of § 7602(g), the majority "simply pretends [the
first] half of [§ 7602(g)], does not exist." Commenters stated that, referring to Webster's
Dictionary, Scalia observes that because the common definition of "pollute" is "to make or
render impure or unclean," and because GHGs "bear little resemblance" to the other
pollutants the EPA typically regulates, the EPA's decision that the CAA did not grant it the
authority to regulate GHGs was the correct one.
Commenters stated that, moreover, the majority in Massachusetts engages in legislative
rewriting when it states that even though "the Congresses that drafted [the CAA] might not
have appreciated the possibility that burning fossil fuels could lead to global warming, they
did understand that without regulatory flexibility, changing circumstances and scientific
developments would soon render the Clean Air Act obsolete."
EPA Response
These comments are out of scope for this final action, as the final action is consistent with
Massachusetts (holding that GHGs are "air pollutants" under the Act-wide definition and
that non-statutory policy reasons are out as to the finding aspect of CAA section 202(a)(1),
as further explained above in this RTC section 2.1.1.1.7). We appreciate the comments and
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note that other judges have raised similar questions to 1 .a of the comment summary
above, including the dissent in Massachusetts, en banc dissents in Coalition, the dissent in
American Lung, and the dissent in West Virginia (which highlighted the difficulties in
reconciliating that decision with a broad reading of Massachusetts). We also agree that
subsequent developments have demonstrated the unworkability, as the EPA foresaw in the
2008 ANPRM, of reading Massachusetts broadly to require the EPA to regulate GHGs
across the statute. Regardless, as explained throughout this RTC section 2.1.1.1, our final
action is not predicated on a different reading of the Act-wide definition of "air pollutant."
Regarding commenters' suggestions in the summarized comment 1 .c above with respect
to the Endangerment Finding, we agree with the commenter, as explained elsewhere, we
are concluding that the best reading of CAA section 202(a)(1) does not authorize the EPA to
prescribe new vehicle and engine emission standards for GHGs in response to global
climate change concerns and that Congress did not clearly authorize the EPA to answer
this extraordinarily important national policy question for itself.
EPA Summary of Comments
Commenters stated that the Proposal also misapplies Massachusetts through its failure to
engage with the Court's recognition of the distinct impacts and harms that climate change
poses for the state of Massachusetts, particularly when the Proposal asserts a reading of
section 202(a) that focuses exclusively on regional or local harms.
EPA Response
See our response above in this RTC section 2.1.1.1, including regarding Massachusetts and
the best reading of CAA section 202(a) and the statutory term "air pollution."
EPA Summary of Comments
Commenters stated that the Court recognized the special position of the States in
vindicating their independent interest "in all the earth and air within its domain."
Commenters stated that, additionally, the Court put weight behind the fact that
Massachusetts owned "a great deal of the 'territory alleged to be affected." Commenters
stated that with this framework, of the States' sovereign role as trustee of natural
resources, in mind, the Court then held that the risk of harm to Massachusetts was
"actual" and "imminent." Commenters stated that the Court then summarized harms
ranging from "significant reduction in water storage," "increase in the spread of disease,"
and increased "ferocity of hurricanes" - all harms that New Jersey itself is also
experiencing.
EPA Response
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See our response above in this RTC section 2.1.1.1, including regarding Massachusetts and
the best reading of CAA section 202(a) and the statutory term "air pollution." We emphasize
that the context of sentences from the decision in Massachusetts matters and note the
difference between the standing or background sections of the decision and the Court's
holdings.
2.1.1.1.8 The Effect of Loper Bright
EPA Summary of Comments
Commenters stated that the EPA misapplies Loper Bright. Commenters stated that the
EPA's reliance on section 202(a) of the CAA to set standards for GHG emissions is not
based on interpretation of statutory ambiguity. Commenters stated that, instead, it is
based on application of the Administrator's judgment. Commenters stated that, in section
202(a), Congress has specifically delegated to the Administrator the duty to use their
judgment to determine which pollutants cause or contribute to air pollution that may
reasonably be anticipated to endanger public health or welfare. Commenters stated that
the Supreme Court explained the Loper Bright decision should not be understood to mean
that Congress "cannot or does not confer discretionary authority on agencies."
Commenters stated that the EPA cannot reverse or rescind the Endangerment Finding
unless the agency can determine that GHGs emissions do not endanger public health or
welfare.
EPA Response
The commenter misunderstands the basis of this final action, which is based on the best
reading of CAA section 202(a)(1) as explained in the final action preamble and RTC section
2.1.1. See also the EPA's discussion in RTC section 2.1.2
2.1.1.2Findings and Standards
In this sub-section we summarize and respond to comments received regardingthe best
reading of CAA section 202(a) as it relates to issuing the standards concurrent with the
Findings and accountingfor policy factors when makingan Endangerment Finding.
2.1.1.2.1 Issuing Standards Concurrent with the Findings Necessary to
Invoke EPA's Regulatory Authority
EPA Summary of Comments
Commenters asserted that the plain text and structure of CAA section 202(a) does not
support the EPA's proposed interpretation of CAA section 202(a), which would require
emission standards to be issued concurrently with an Endangerment Finding. They argue
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that the EPA fails to identify what text in CAA section 202(a)(1) purportedly mandates that
the EPA make the findings required under that provision in a single analysis.
Commenters contended that the statute establishes a two-part analytical framework: first,
the Administrator must determine whether emissions from motor vehicles "may
reasonably be anticipated to endanger public health or welfare," and second, the
Administrator must prescribe standards for those emissions. They argued that nothing in
the text requires these distinct determinations be made simultaneously or published in the
same regulatory action.
Some commenters also argued that because an affirmative Endangerment Finding is a
predicate to the issuance of standards, the EPA must, as a practical matter, complete the
administrative work on that issue before it begins developing standards, lest it expend
agency resources only to subsequently find that it lacks standard-setting authority. Their
stated view is that while the statute certainly permits the Agency to undertake both actions
in a single rulemaking docket, it would be absurd to require that the EPA sit on a completed
contribution/Endangerment Finding and decline to make it public simply because it had
notyet completed its development of vehicle standards for which that finding was a
prerequisite.
Commenters also argued that the EPA's interpretation is incompatible with CAA section
202(a)(1 )'s directive that the Agency "from time to time revise" its vehicle standards. They
contended that at the time of deciding the endangerment question, it would be impossible
for the Agency to account for the economic impacts and other practical consequences of
its standard-setting exercise when Congress intended those standards to change over time
through periodic revisions. The only other possibility, commenters contended, is that the
Agency must also revise its predicate determination each time it revises a standard. Yet,
commenters argued, the EPA has never suggested, and does not now assert, that such a
thing is required under section 202(a)(1).
EPA Response
The EPA acknowledges that a finding of endangerment and the setting of standards are
discrete analytical steps and acknowledges that Coalition for Responsible Regulation held
as much. 684 F.3d 102,118. But for the reasons explained in Section V.A.I of the final action
preamble, and for the reasons set forth below examining CAA section 202(a) in the context
of the CAA's whole statutory scheme, the EPA believes that the best reading of the statute
is that a finding of endangerment under section 202(a) can only be made in the action of
settingthe vehicle standards themselves and such a finding must be on the basis of or
sustainable by reference only to those new mobile source emissions to which the
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emissions standards would apply. Coalition for Responsible Regulation never addressed
this procedural issue that issuingthe Endangerment Finding as a standalone action was
beyond the EPA's authority under the Act.
To the extent that commenters read the NPRM and final action to suggest that
simultaneous promulgation of an Endangerment Finding and vehicles standards would
necessarily require that administrative work on the vehicles rules happen concurrently with
administrative work on endangerment, commenters misread the NPRM. Obviously, the
Agency has full remit to organize and sequence the use of its resources internally, which
would necessarily involve different spheres of expertise, different staff, and even,
potentially, wholly different offices and disciplines. Regardless of how the work is staffed,
the public facing agency "action" that the Agency may take under CAA section 202(a) must
be singular.
Finally, the approach taken in this final action is not incompatible with the statutory
directive in CAA section 202(a)(1) to "from time to time revise" the EPA's vehicle standards.
Notably, CAA section 202(a)'s "revision" provision lacks a specific timeframe - unlike, for
example, CAA section 111 (b), which requires the Administrator to "review and, if
appropriate, revise" emissions standards for certain stationary sources every eight years.
We disagree that the Agency's best reading of CAA section 202(a)(1) regarding findings and
standards would necessarily require the EPA to make a new Endangerment Finding every
time it revised an emissions standard for an air pollutant from a class or classes of new
motor vehicles or new motor vehicle engines that the EPA had already concluded "causes,
or contributes to, air pollution which may reasonably be anticipated to endanger public
health or welfare." The EPA anticipates that so long as such determination has been
properly made, the Agency could rely on that previous finding when revising vehicles
emissions standards in the future.
EPA Summary of Comments
Several commenters argued that CAA section 202(a) is silent on the timing of the
Endangerment Finding and the issuance of related standards and therefore authorizes the
EPA to issue an Endangerment Finding either before, or concurrent with, the vehicles
standards. These commenters stated that while the 2009 Endangerment Finding took the
position that CAA section 202(a)(1) was "silent" on "the timing of an Endangerment
Finding" relative to standard-setting, the Agency notably did not rely on Chevron deference
in doing so.
These commenters argued that the Supreme Court has already noted that the statute gives
the EPA latitude when issuing vehicles standards: "If EPA makes a finding of endangerment,
the [CAA] requires the Agency to regulate emissions of the deleterious pollutant from new
motor vehicles ... EPA no doubt has significant latitude as to the manner, timing, content,
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and coordination of its regulations with those of other agencies." Massachusetts v. EPA,
549 U.S. 497, 533 (2007). They further argue that the Court in Massachusetts also seemed
to understand section 202(a) as requiring two distinct steps: "Under the clear terms of the
Clean Air Act, EPA can avoid taking further action only if it determines that greenhouse
gases do not contribute to climate change or if it provides some reasonable explanation as
to why it cannot or will not exercise its discretion to determine whether they do."
Massachusetts, 549 U.S. at 533 (2007) (emphasis added).
EPA Response
As explained in the final action, CAA section 202(a) is not silent on the issue of timing
because the statute sets out an integrated process that requires the EPA to prescribe
standards when the Administrator finds certain conditions are met. And even if it were
silent, the best reading of the statute in the context of the CAA's statutory scheme as a
whole is that that the two steps must happen concurrently.
Regarding the statements by the Court in Massachusetts quoted by commenters, the EPA
notes that the issue of whether an Endangerment Finding and any resulting regulations
must be promulgated simultaneously was not squarely before the Court in that case, and
the quoted language is not a holding of a question presented to the court. See RTC at
Section 2.1.1.1.7 for further discussion of the precise holdings of Massachusetts v. EPA.
Granted, CAA section 301 (a)(1) supplies the EPA with the authority to "prescribe such
regulations as are necessary to carry out his functions under 'the Act.'" But that provision
does not supply substantive authority where it is otherwise lacking, and it cannot override
the plain language of the operative provisions of the Act, such as CAA section 202(a)(1),
which only authorizes a finding of endangerment in conjunction with an action issuing
standards. Nor could the "one step at a time" doctrine rehabilitate the lawfulness of the
Endangerment Finding. This is not a situation in which an agency has appropriately taken
an incremental step toward an overall statutory objective where Congress had "no specific
timetable in mind." Wisconsin v. EPA, 938 F.3d 303, 319 (D.C. Cir. 2019) (quoting Grand
Canyon Air Tour Coal. v. FAA, 154 F.3d 455, All (D.C. Cir. 1998)); cf. Massachusetts, 549
U.S. 497, 524 (citing one-step-at-a-time caselaw in finding rulemaking petitioners had
standing). Rather, CAA section 202(a) unambiguously expresses the particular authority
that the EPA has in this regard, and that language does not allow for a bifurcated approach
in which a finding of endangerment can be made separate from an action settingthe
relevant standard. See Wisconsin, 938 F.3d at 319 (rejecting one-step-at-a-time argument
where an action partially fulfilling a statutory duty was at odds with statutorily mandated
schedule). For the reasons explained in the final action preamble, this error, even if only
considered procedural, infected the EPA's substantive analysis. Cf. CAA section 307(d)(8)
(authorizing judicial invalidation of rules where procedural errors are "so serious and
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related to matters of such central relevance to the rule that there is a substantial likelihood
that the rule would have been significantly changed if such errors had not been made.")
EPA Summary of Comments
The EPA received comments averring that the other CAA provisions the EPA cites in the
NPRM as exemplifying multi-step inquiries do not support the EPA's proposed
interpretation of CAA section 202(a) and that numerous examples of other CAA provisions
contradict the EPA's proposed interpretation.
Focusing on the NAAQS program, commenters contended that this program proves the
opposite of the EPA's premise: when Congress wants the EPA to issue concurrent findings,
it uses clear language to so direct. Regardingthe SIP provisions cited in the NPRM,
commenters stated that those differ dramatically from CAA section 202(a). They argue that
section 202(a) calls for the EPA to determine contribution to air pollution that endangers; if
and only if the EPA makes an affirmative determination, the EPA is to adopt controls that
reduce emissions using the standard setting provisions of section 202. The determination
of contribution to the air pollution and the determination of standard setting are two
separate decisions. Commenters state that the SIP provision is different - the
determination of significant contribution requires the EPA to determine the amount of
emissions from an upwind state that must be reduced. Commenters contend that the
decision on contribution and the decision on what reductions must be achieved are one
and the same, which is substantively different from section 202(a), and the factors the EPA
can consider under the Good Neighbor SIP provision do not support their consideration
under section 202(a).
Commenters note that the EPA in the NPRM also cited CWA section 303(c)(4) and (c)(4)(B)
as provisions that expressly establish a multi-step regulatory structure. But, commenters
argue, these CWA provisions are completely unlike CAA section 202 - they are applied
when the EPA disapproves a state's standards forfailure to comply with the CWA, after
which the EPA must promulgate regulations to supersede the disapproved provisions.
Commenters state that the language used in the CWA differs from the language used in
section 202(a) and therefore has no bearing on 202(a)'s interpretation. Furthermore, they
state, CWA section 304(c)(4)(B) provides that the "[t]he Administrator shall promptly
prepare and publish proposed regulations setting forth a revised or new water quality
standard for the navigable waters involved ... in any case where the Administrator
determines that a revised or new standard is necessary to meet the requirements of this
chapter," and then requires that the EPA finalize those regulations "within ninety days" of
the proposal's release. 33 U.S.C. § 1313(c)(4), (c)(4)(b) (emphasis added). Commenters
argue that the fact that the provisions demand a "prompt" proposal and then finalization
within a mere 90 days - an extraordinarily rapid timeframe - indicate that Congress's main
purpose here was to expedite the rulemaking process.
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Commenters assert that the lack of similarly urgent language under CAA section 202(a)
does not mean that the Agency can or should move slowly when issuing vehicle standards,
but even less does it mean that the Agency must undertake the threshold and standard-
setting processes at the same time, even while the statutory language permits it to do so.
The EPA also received comments stating that Congress used the same basic two-step
structure employed in CAA section 202(a) throughout various provisions of the Act
addressing the EPA's authority to adopt federal controls on emissions sources, and that
the consistent use of the same basic statutory structure throughout the Act supports the
interpretation that, unless otherwise specified, the two actions are not required to occur
simultaneously. See, e.g., CAA sections 108, 112,122, 202, 211, 213, 231, 303, 602, 615.
Commenters state that CAA section 122 specifically includes a reference to the
Administrator "simultaneously" taking two actions, indicating that if Congress wanted to
include such language in section 202(a), it certainly could have: "The Administrator shall
review all available relevant information and determine whether or not emissions of
radioactive pollutants ... cadmium, arsenic and polycyclic organic matter into the
ambient air will cause, or contribute to, air pollution which may reasonably be anticipated
to endanger public health. If the Administrator makes an affirmative determination with
respect to any such substance, he shall simultaneouslyw\X.h such determination include
such substance in the list published under [the NAAQS or NSPS]." (emphasis added in
comment).
Commenters state that the EPA has very recently sought judicial vacatur of PFAS
regulations promulgated in 2024 under the theorythat the Safe Drinking Water Act
prohibits the concurrent issuance of a threshold determination to regulate and the
regulations themselves, since doing so would (the EPA claims) deprive the public of an
adequate opportunity to comment on the Agency's course of action, but that the EPA
raises no such concerns with regard to its newfound interpretation of section 202(a)(1).
See Resps.' Mot. for Partial Vacatur, Am. Water Works /Assoc., etal, v. EPA, No. 24-1188
and consolidated cases, No. 2134523 at 18-19 (D.C. Cir. Sept. 11, 2025).
EPA Response
It is true that the CAA is rife with examples of "two-step inquiries" for Endangerment
Findings and regulation of a particular emissions source. But a close examination of CAA
section 202(a) in comparison to other statutory "two-step" provisions indicates that the
better reading of that particular statutory provision is the one now being finalized herein. A
statutory "provision that may seem ambiguous in isolation is often clarified by the
remainder of the statutory scheme ... because only one of the permissible meanings
produces a substantive effect that is compatible with the rest of the law." UARG v. EPA, 573
U.S. 302, 321 (2014) (quoting United Sav. Assn. of Tex. v. Timbers of Inwood Forest
Associates, Ltd., 484 U.S. 365, 371 (1988)).
Unlike CAA section 202(a), some statutory provisions contain dates certain or specific time
frames for certain actions, and the predicate finding akin to "endangerment" and the
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consequent regulations are housed in separate paragraphs (see, e.g., CAA §§ 108,112,
213). In such instances, the two steps are clearly distinct. Clearly CAA section 202(a) does
not follow this statutory structure because it instructs the EPA to "from time to time"
prescribe regulations based on a finding of endangerment — within the same statutory
paragraph (subsection) - as opposed to breaking out the two steps in separate
subsections.
Also, unlike CAA section 202(a), at least one CAA provision provides for "simultaneous"
agency action. See CAA § 122(a).
Other statutory provisions leave more discretion to the Administrator in terms of timing.
See, e.g., CAA § 231 (requiring a study of emissions of air pollutants from aircraft to be
commenced upon a date certain, and instructingthe Administrator to issue proposed
regulations "from time to time" for those pollutants from aircraft engines which, in his
judgment, "cause or contribute").
Even if CAA section 202(a) were silent on the issue, it is clear based on the textual structure
of the CAA and the numerous examples of clear "two-step" inquiries throughout the statute
that CAA section 202(a) is not like those examples. While 202(a) does not explicitly say
"simultaneously" like at least one other CAA provision, it also does not specify certain
timeframes like other CAA provisions. And the "two-step inquiry" in CAA section 202(a)
resides in the same paragraph (unlike other CAA provisions, which break up the two).
Congress clearly structured section 202(a) differently. The better reading, in the context of
the CAA as a whole, is that Congress intended the two actions to be taken together. See
UARG, 573 U.S. at 321.
As noted by the Court in Loper Bright, some statutes "empower an agency to prescribe
rules to 'fill up the details' of a statutory scheme, or to regulate subject to the limits
imposed by a term or phrase that 'leaves agencies with flexibility,' such as 'appropriate' or
'reasonable.'" Loper Bright, 603 U.S. at 395 (2024). The Court provided two environmental
statutes as examples: CWA section 302(a) (requiring establishment of effluent limitations
"[wjhenever, in the judgment of the [Environmental Protection Agency (EPA)] Administrator
..., discharges of pollutants from a point source or group of point sources ... would
interfere with the attainment or maintenance of that water quality... which shall assure"
various outcomes, such as the "protection of public health" and "public water supplies")
and CAA section 112(n)(1)(A) (directing the EPA to regulate power plants "if the
Administrator finds such regulation is appropriate and necessary"). See also Waterkeeper
All. v. EPA, 140 F.4th 1193,1215-16 (9th Cir. 2025) (in setting effluent limitations, the EPA
has discretion to select the manner and method of its review based on the statute's use of
"if appropriate" and "from time to time" revise). Just like these statutory provisions, CAA
section 202(a) leaves it to the Administrator to, "in his judgment," prescribe vehicles
standards.
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While commenters cite to arguments made by the EPA in litigation regarding the SDWA,
that case and the legal issues presented therein have no bearing on the best reading of CAA
section 202(a) that the EPA is finalizing in this rule. The EPA's reading of CAA section 202(a)
to require a simultaneous determination of endangerment and regulation does not present
the same notice and comment challenges referenced in the SDWA litigation because the
statutory language in the SDWA specifically requires the Agency to take a seriatim
approach to regulation - the Agency must first propose to regulate a particular drinking
water contaminant and seek public comment on whether regulation is appropriate. 42
U.S.C. § 300g-1 (b)(1)(E). Only after the public has had the opportunity to comment on that
proposal and when the EPA has finalized a determination to regulate may the EPA publish a
proposed regulation of that contaminant, either simultaneously with the final regulatory
determination or after that final determination. Id. CAA section 202(a) contains no such
language regarding a mandatory comment period.
EPA Summary of Comments
The EPA received comments stating that the agency's regulatory history contradicts its
claim that it must issue the threshold finding concurrently with standards. Commenters
take issue with the EPA's position stated in the NPRM that its interpretation aligns with pre-
2009 implementation processes, where standards and threshold findings were typically
concurrent. But during that time frame, commenters argued, the EPA never claimed that it
was required to undertake these processes concurrently and that, in fact, before 2009, the
EPA did issue standards under section 202(a)(2) that relied on preexisting findings that the
pollutant endangers the public health or welfare.
Commenters state that, for example, in establishing Tier 2 Motor Vehicle Emissions
Standards and Gasoline Sulfur Control Requirements, the EPA briefly summarized the
health impacts of ozone and then simply concluded that "ozone concentration patterns
causing violations of the 1 -hour [National Ambient Air Quality Standards] are well
established to endanger public health or welfare." 65 FR at 6708. Similarly, commenters
assert, in describing air pollutants that cause or contribute to air pollution which
endangers the public health or welfare in support of a 1994 light-duty truck emission
regulation, the EPA explained that "[h]ydrocarbons, as ozone precursors, have long been an
essential object of emission control strategies (both vehicles and non-vehicles)." 59 FR
16262,16263 (Apr. 6,1994). Thus, commenters argue, for decades, the EPA has relied on
prior findings of health impacts to support new regulatory standards.
EPA Response
For the reasons explained in the final action at Section IV.A.I, the EPA is finalizing its
approach to findings and standards as the best reading of CAA section 202(a). To the extent
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that commenters provide counterexamples to the EPA's statements in the NPRM and in the
2009 Endangerment Finding that "typically endangerment and cause or contribute findings
have been proposed concurrently with proposed standards undervarious sections of the
CAA, including CAA section 201 (a)," 74 FR 66501, the EPA acknowledges these examples
but does not find them to be persuasive enough to change course. To the extent that
commenters are commenting on a change in agency practice and position, see RTC
section 1.1.1.2.
2.1.1.2.2 Accountingfor Policy Factors when Makingan Endangerment
Finding
EPA Summary of Comments
Commenters argued that Massachusetts and Coalition for Responsible Regulation
establish that policy factors (e.g., costs, benefits, adaptation efforts and mitigation efforts)
cannot be considered when making an Endangerment Finding. In Massachusetts,
commenters contended, the Supreme Court rejected the EPA's reliance on policy-based
justifications - including implementation issues and foreign policy concerns -to avoid
making an Endangerment Finding under section 202(a)(1), and therein squarely held that
"policy judgments ... have nothing to do with whether greenhouse gas emissions
contribute to climate change. Still less do they amount to a reasoned justification for
declining to form a scientific judgment." 549 U.S. at 533-34. And commenters argued that
Coalition for Responsible Regulation, Inc. v. EPA, 684 F.3d 102 (2012) is even more on point:
there, they argue, the D.C. Circuit considered and rejected the precise arguments against
the 2009 Endangerment Finding that the EPA now asserts. Commenters state that the
NPRM includes no reference to Coalition, even while that opinion directly forecloses the
Agency's argument. The D.C. Circuit explained and held in Coalition:
[Industry Petitioners] . .. assert that CAA § 202(a)(1) requires EPA to consider, e.g.,
the benefits of activities that require greenhouse gas emissions, the effectiveness of
emissions regulation triggered by the Endangerment Finding, and the potential for
societal adaptation to or mitigation of climate change. They maintain that eschewing
those considerations also made the Endangerment Finding arbitrary and capricious.
These contentions are foreclosed by the language of the statute and the Supreme
Court's decision in Massachusetts v. EPA.
The additional exercises State and Industry Petitioners would have EPA undertake—
e.g., performing a cost-benefit analysis for greenhouse gases, gauging the
effectiveness of whatever emission standards EPA would enact to limit greenhouse
gases, and predicting society's adaptive response to the dangers or harms caused by
climate change—do not inform the "scientific judgment" that § 202(a)(1) requires of
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EPA.... To be sure... § 202(a)(2) requires that EPA address limited questions about the
cost of compliance with new emission standards and the availability of technology
for meeting those standards, but these judgments are not part of the § 202(a)(1)
endangerment inquiry. The Supreme Court made clear in Massachusetts ... that
policy concerns were not part of the calculus for the determination of the
Endangerment Finding in the first instance. The Supreme Court emphasized that it
was holding "that EPA must ground its reasons for action or inaction in the
statute." Id. at 535. The statute speaks in terms of endangerment, not in terms of
policy.
634 F.3d at 117-19.
Commenters state that even if mitigation and adaptation could or should be taken into
account in making an Endangerment Finding, the NPRM does not reflect any attempt to
grapple with how to do so. Commenters perceive an absence of factual evidence, analysis,
and explanation of how adaptation and mitigation could and should be taken into account
in an Endangerment Finding and dub them a basic failing of reasoned decision-making.
EPA Response
For the reasons explained in the final action at Section V.A.I, the EPA finds that the 2009
Endangerment Finding was unlawfully severed from the emissions standards that followed.
As noted in the final action, the Supreme Court's decision in Massachusetts did not
address the question of whether the EPA could issue standalone findings or barthe
Administrator from taking cost and implementation concerns into account when exercising
CAA section 202(a) authority in an action that appropriately includes both an
Endangerment Finding and the related emissions standards. While the EPA acknowledges
the Court's statements in Coalition, such statements were within the context of action
following a standalone endangerment finding. As we further discuss in RTC 2.1.1.1.7,
courts can, and often do, consider the same regulatory issue in multiple cases that
address the reasoning and arguments in front of them each time. It can take multiple
rounds to get at all of the possible legal issues. In this action, the EPA is setting forth
several particular legal arguments, not previously considered, as to why GHGs, even if air
pollutants, cannot be the kind of air pollution that is subject to regulation under CAA
section 202(a)(1). Our reading is the best reading of the Act. For additional discussion of
issues presented and specific holdings in Coalition and UARG, see RTC at 2.1.1.1.1;
2.1.1.1.7, and 2.1.2. See also final action at Section V.A.
Regarding commenters' statements about how the EPA should consider factors such as
mitigation and adaptation, the EPA notes that this rulemaking is solely focused on
rescinding the 2009 Endangerment Finding, in part based on its failure to consider
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adaptation, mitigation, and other factors, not about setting out parameters for future
Endangerment Findings and emissions standards.
EPA Summary of Comments
Commenters contend that the NPRM misapplies Michigan v. EPA, 576 U.S. 743 (2015), to
suggest that the EPA must consider cost when making an Endangerment Finding under
CAA section 202(a)(1). Commenters state that Michigan considered how to interpret the
phrase "appropriate and necessary" as it appears in a different CAA provision: section
112(n)(1 )(A), and that the Court found that the word "appropriate" is a "classic broad and
all-encompassing term that naturally and traditionally includes consideration of all the
relevant factors." Id. Further, commenters state, the Court concluded that the
determination of whether "regulation is 'appropriate and necessary' requires at least some
attention to cost." Id. But commenters contend that neither the phrase "necessary and
appropriate," nor anything remotely analogous to it, appears in CAA section 202(a)(1).
Instead, they argue, section 202(a)(2) only directs the EPA to give "appropriate
consideration to the cost of compliance" specifically when determiningthe content and
timing of for new standards - not when evaluating whether regulation is required in the first
instance.
Commenters state that the EPA cannot distort the plain text of the statute to insert cost
considerations in section 202(a)(1), but that the EPA nevertheless attempts to do so by
pointingto section 202(a)(1)'s language requiringthat new standards be issued "in
accordance with the provision of this section," - provisions that include section 202(a)(2).
But, commenters argue, CAA section 202(a)(2)'s cost considerations impact new
standards' content, timing, and stringency, not the Administrators' predicate findings
concerning air pollution.
Commenters further state that economic considerations belong in the standard-setting
phase and that the EPA's approach would result in double counting: considering costs and
benefits both in determining whether a pollutant causes harm and whether regulation is
worthwhile. Thus, commenters contend, while Michigan can support consideration of
costs in determining what regulation is appropriate, the EPA's approach of considering
costs multiple times over is unsupported.
Commenters also argued that the listing of cost and technology as considerations in
section 202(a)(2) bolsters the conclusion that those considerations cannot inform the
Administrator's "judgment" referenced in section 202(a)(1). Cf. Whitman v. Am. Trucking
Ass'ns, 531 U.S. 457,466-68 (2001). And commenters state that the EPA does not point to
any historical examples where it injected cost into a threshold finding under section
202(a)(1), even when the Agency concurrently established standards alongside that
determination. In those circumstances, commenters state, the EPA has discussed costs,
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but solely in the context of the standard-setting exercise itself - not the discussion of the
health and welfare effects, or contributions to total emissions.
EPA Response
The EPA disagrees that it cannot consider cost or that it misapplies Michigan. As explained
in Section IV.A.I of the final action, CAA section 202(a)(1) sets out an integrated authority to
prescribe emissions standards when the provision's triggering condition is satisfied. The
language of CAA section 202(a)(1) must be read in context to "produc[e] a substantive
effect that is compatible with the rest of the law." UARG, 573 U.S. at 321 (quoting United
Sav. Ass'n of Tex. v. Timbers of Inwood Forest Assocs., 484 U.S. 365, 371 (1988)). Under
Michigan, the Supreme Court stated that agencies must consider cost when promulgating
any regulation. Because CAA section 202(a)(1) requires the Administrator to use "his
judgment," - a similarly deferential and capacious phrase as "appropriate and necessary"
in CAA section 112((n)(1)(A) that the Court examined in Michigan - it follows that under
Michigan the Administrator could at least consider cost to some appropriate extent.
Because we conclude that the Endangerment Finding and related vehicle emissions
standards must be issued in a simultaneous action, and because the Supreme Court
instructed in Michigan that "agency action is lawful only if it rests 'on a consideration of the
relevant factors,'" 576 U.S. at 750 (quoting State Farm, 463 U.S. at 43), including "at least
some attention to cost," id. at 752, the EPA finds that it was in error for the Endangerment
Finding to not take cost into consideration at all.
Notably, the majority opinion's treatment of the dissent in Michigan speaks to the
consideration of costs, and is informative here:
The dissent does not embrace EPA's far-reaching claim that Congress made
costs altogether irrelevant to the decision to regulate power plants. Instead,
it maintains that EPA need not "explicitly analyze costs" before deeming
regulation appropriate, because other features of the regulatory program will
on their own ensure the cost-effectiveness of regulation. This line of
reasoning contradicts the foundational principle of administrative law that a
court may uphold agency action only on the grounds that the agency invoked
when it took the action. SEC v. Chenery Corp., 318 U.S. 80, 87 (1943). When
it deemed regulation of power plants appropriate, EPA said that cost was
irrelevant to that determination — not that cost-benefit analysis would be
deferred until later. Much less did it say (what the dissent now concludes)
that the consideration of cost at subsequent stages will ensure that the
costs are not disproportionate to the benefits. What it said is that cost is
irrelevant to the decision to regulate.
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That is enough to decide these cases. But for what it is worth, the dissent
vastly overstates the influence of cost at later stages of the regulatory
process....All in all, the dissent has at most shown that some elements of
the regulatory scheme mitigate cost in limited ways; it has not shown that
these elements ensure cost-effectiveness.
Michigan, 576 U.S. at 757-58.
Regarding the relevance of Whitman v. American Trucking Ass'ns., Inc., 531 U.S. 457 (2001)
raised by commenters, see discussion in the final action at Section V.A.1.
2.1.1.3Endangerment and Cause or Contribute
In this sub-section we summarize and respond to comments received regardingthe best
reading of CAA section 202(a) as it relates to endangerment and cause or contribute.
2.1.1.3.1 The nexus between contribution and endangerment
EPA Summary of Comments
Commenters allege that the proposal incorrectly interprets CAA section 202(a)(1) to
require a finding that the specific emissions from the class or classes of new motor
vehicles cause or contribute to the endangerment to a sufficient extent to justify regulation.
These comments reject the proposal's contention that the Endangerment Finding
improperly severed the contribution and endangerment analyses.
Commenters claim that the failure to separate "cause or contribute" from "endangerment"
greatly raises the bar for what needs to be proven to establish endangerment and gives the
incorrect impression that it is necessary to prove that emissions from regulated vehicles by
themselves make a substantial contribution to the harms resulting from climate change.
They argue that the EPA's "severance theory" would create irrational gaps in regulation by
allowing a pollutant to be found to cause dangerous air pollution but evade control
because its effects are distributed across multiple source categories.
Commenters allege that the plain text of section 202(a)(1) and the broader statutory
scheme do not support requiring the specific emissions from the class or classes of new
motor vehicles at issue to cause or contribute to endangerment to a sufficient extent to
justify regulation.
Commenters allege that Congress does not ask the EPA to determine whether vehicles' "air
pollutant" emissions themselves endanger public health or welfare but asks whether they
cause or contribute to "air pollution" and then explain that that "air pollution" must
endanger public health or welfare. Commenters claim the use of both "air pollutant" and
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"air pollution" in the same sentence would make little sense unless Congress meant to
distinguish between what is actually emitted by vehicles and an accumulated mass in the
atmosphere that is endangering health and welfare.
Commenters allege that the word "contribute" must play a textual role distinct from
"cause" and therefore assumes there is more than one source of "air pollution" apart from
motor vehicles when analyzing endangerment. They claim the EPA effectively reads the
words "contribute to" out of the statute, asking whether such emissions themselves
"cause" dangerous air pollution. See United States v. Philip Morris USA, Inc., 396 F.3d
1190,1198 (D.C. Cir. 2005) (explaining that courts should "strive to give meaning to every
word"). Commenters say that by its very nature, "contribute" assumes there is more than
one source of atmospheric contaminants in question apart from vehicles.
EPA Response
Many of these commenters misunderstand and overstate the EPA's position on the
relationship between the "cause or contribute" and "endangerment" analyses under CAA
section 202(a)(1). The EPA does not disagree with commenters that section 202(a)(1)
requires distinct "contribution" and "endangerment" analyses. The EPA does not read CAA
section 202(a)(1) to require a finding that emissions from new motor vehicles themselves
"significantly contribute" to or exclusively "cause" air pollution that endangers public
health orwelfare. Nor does the Agency take the position, as suggested by some
commenters, that we cannot find section 202(a)(1 )'s standard satisfied where other
sources also contribute to the "air pollution" at issue. The EPA does not raise the bar for
regulation, but rather is faithful to the statutory text, which requires "contribution" and
"endangerment" in a single causal chain.
What commenters and the Endangerment Finding get wrong is that under CAA section
202(a)(1) there must be at least some nexus between emissions from new motor vehicles
and endangerment to satisfy the standard for regulation. In other words, the "air pollution"
that vehicle emissions contribute to has to be the same "air pollution" that endangers
public health and welfare. Both the de minimis principle and judicial maxim on futility
support this understanding. The de minimis principle, as explained by the D.C. Circuit in
the context of the CAA in Alabama Power Co. v. Costle, provides that the EPA need not
regulate de minimis emissions. 606 F.2d 1068,1081 (D.C. Cir. 1979). As a textual matter,
this means, for example, that "contribute" in section 202(a)(1) must be read as not
encompassing a de minimis contribution. The judicial maxim on futility provides that it is
not appropriate to presume Congress would enact legislation requiring an agency to
perform ineffective regulatory exercises, unless the statute provides unmistakably clear
direction or express authorization to the contrary. See Jackson v. S.S. Archimedes, 275 U.S.
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463, 468 (1928) ("a purpose so wholly futile is not to be attributed to Congress."). In light of
these interpretive principles, the error of the Endangerment Finding's severing of the
contribution and endangerment analyses becomes clear. Section 202(a)(1) does not
provide unmistakably clear language that would allow for ineffective regulatory exercises or
require the regulation of de minimis emissions. Yet, if no nexus is required between
contribution and endangerment, it would be permissible to do exactly that by allowing the
EPA to promulgate standards under section 202(a)(1) for pollutants that contribute to air
pollution to any degree, even if such standards would have no impact on any of the dangers
to public health or welfare associated with that air pollution.
In order to demonstrate a nexus between motor vehicle emissions and endangerment, it is
necessary to analyze the relevant air pollution in the same way when assessing
contribution and when assessing endangerment.
The 2009 Endangerment Finding was unfaithful to the statutory scheme established in CAA
section 202(a)(1) by totally severing the link between the contribution and endangerment,
allowing it to assess contribution and endangerment at different temporal and
geographical scales, such that it was not assessingthe same air pollution in each inquiry,
so to speak. Severing endangerment and contribution concealed these analytical
mismatches, as well as the lack of a nexus between contribution and endangerment.
First, there is a temporal problem with the Endangerment Finding's analysis. When
determining contribution, the Endangerment Findingfound that motor vehicle emissions
contribute to annual emissions. However, when determining endangerment, the
Endangerment Finding found that elevated concentrations of global GHGs that result from
historic, present, and future emissions are contributing to climate change and endangering
public health and welfare. Clearly annual emissions is a much smaller figure, and due to
the long-lived nature of GHGs in the atmosphere, the mismatch obfuscates the fact that
there is no nexus between GHG emissions from new motor vehicles and the endangerment
of public health and welfare from global past, present, and future GHG emissions. Any
change in annual GHG emissions will have no impact on the effect of these total GHGs in
the atmosphere.
Second, there is a geographical problem with the Endangerment Finding's analysis. In
severing the contribution and endangerment analyses, the endangerment analysis is able
to make a jump from domestic emissions to global emissions to find that global GHGs
endanger public health and welfare. In fact, the Endangerment Finding is only able to link
GHG emissions to endangerment by bringing in all foreign sources. Domestic emissions
alone would not contribute to air pollution that endangers public health orwelfare as
contemplated by the statute. Similarly, the Endangerment Finding recognized that foreign
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sources would also have to be reduced to have any impact on the danger identified. After
making the jump to global emissions, the Endangerment Finding used those findings to
justify domestic regulations under section 202(a)(1). Again, because of this mismatch
resulting from severance of endangerment from contribution there is not a sufficient nexus
between motor vehicles' contribution to domestic GHG emissions and the dangers to
public health and welfare associated with global GHG emissions. Furthermore, the very
fact that the Endangerment Finding required severance and this global leap to "satisfy" the
requirements of section 202(a)(1) demonstrates the fundamental mismatch between the
statute and the type of problem that the Endangerment Finding sought to address. The CAA
is concerned with domestic emissions and domestic impacts, with very narrow exceptions
that are explicitly laid out in the statute. See 42 U.S.C. § 7671.
A glance at regulatory history in this space also reveals the novelty of the EPA's approach to
the causation and endangerment analyses in the Endangerment Finding. The EPA generally
in the past did not undertake separate analyses of endangerment and contribution for the
purposes of standard setting under CAA section 202(a)(1). See, e.g., 65 FR 6709 ("Because
ozone concentration patterns causing violations of the 1 -hour NAAQS are well established
to endanger public health or welfare, this determination also supports our actions today
under the general authority of sections 202(a)(1), 202(a)(3), and 202(b)."). The EPA even
seemed to acknowledge the existence of some nexus between the endangerment and
contribution determinations in the 2009 Endangerment Finding when discussing
contribution. The Endangerment Finding notes that because of the "unique totality of the
circumstances" surrounding GHG emissions and global climate change, contribution may
be "smaller than typically encountered when tackling solely regional or local environmental
issues," and asserts that contribution to GHG pollution from CAA section 202(a) sources "is
anything but trivial or de minimis." 74 FR 66543. This acknowledgment seems to tie
contribution notjust to the emissions, but to the "issue" or"problem" which endangers
public health or welfare. Furthermore, when assessing contribution to domestic annual
GHG emissions, the Endangerment Finding notes that CAA section 202(a) sources are the
second largest emitter of GHGs in the country (at roughly 28 percent). Id. at 66540. This
does not point towards a "smaller than typical" contribution finding, suggesting that the
EPA's admission in that regard more reasonably relates to the impact of those emissions on
global climate change and their subsequent impacts on health and welfare.
The difficulties in analyzingthe nexus between contribution and endangerment for GHGs
further demonstrates that CAA section 202(a)(1) was not designed to address global
climate change.
EPA Summary of Comments
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Commenters assert that case law does not support the contention that the EPA must
consider whether specific emissions cause or contribute to air pollution and
endangerment in a single causal chain.
They say that the D.C. Circuit in Ethyl Corp v. EPA held that "causes or contributes" in
section 202(a)(1) "refers to the relationship between automobile emissions and air
pollution," with the EPA's task being to "determine whether the emitted air pollutant, which
would be regulated, contributes to the air pollution which is found dangerous." 541 F.2d 1,
15 (D.C. Cir. 1976). Commenters also allege that Massachusetts made clear that the
relevant question regarding endangerment is not whether vehicles' GHG emissions
endanger public health or welfare by causing climate change, but whether GHGs as a class
do so. They claim that the EPA's "severance theory" repackages the policy concerns the
Supreme Court rejected in Massachusetts as irrelevant to avoid making an endangerment
determination. Commenters claim they are likewise irrelevant for the purposes of making
an affirmative or negative determination on contribution or endangerment.
They say that Coalition for Responsible Regulation confirms the Court's reading in
Massachusetts, pointing to the following passage: "At bottom, § 202(a)(1) requires EPA to
answer only two questions: whether particular 'air pollution'—here, greenhouse gases—
'may reasonably be anticipated to endanger public health or welfare,' and whether motor-
vehicle emissions 'cause, or contribute to' that endangerment. These questions require a
'scientific judgment' about the potential risks greenhouse gas emissions pose to public
health orwelfare—not policy discussions." 684 F.3d 102,117-18 (D.C. Cir. 2012).
EPA Response
A close examination of the cases cited by commenters to support the Endangerment
Finding's severance of endangerment and causation reveals that they do not speak to the
question of severance at all and certainly do not bar the EPA from taking the position that
the Agency is taking here - that there must be a nexus between contribution and
endangerment. First and foremost, it is important to recognize that Ethyl Corp and
Massachusetts both preceded the Endangerment Finding.
In Ethyl Corp, the D.C. Circuit analyzed the "cause or contribute" standard in section
202(a)(1) in comparison to the threshold to regulation in section 211, with the language
quoted by commenters specifically focusing on whether the word "likely" should be
attributed to the contribution or endangerment analysis, ultimately concluding only that
under section 202, "air pollution must endanger the public health before regulation is
justified." Ethyl Corp. v. EPA, 541 F.2d at 16. While the court does not speak directly to - nor
did it have reason to speak directly to - the severability of the contribution and
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endangerment determinations, the court appeared to analyze the standard the way that
the EPA applies it here. The court noted that under section 202(a)(1), the threshold for
regulation is a "chain of causation" requiring "a determination that an air pollutant emitted
from a new automobile is likely to contribute to air pollution which endangers the public
health." Id. This discussion suggests that contribution and endangerment are considered in
a single causal chain, such that there is a nexus between the two findings.
The Court in Massachusetts had no occasion to anticipate that the EPA would sever the
contribution and endangerment analyses in the Endangerment Finding, and thus no reason
to speak to whether this would be the proper reading of section 202(a)(1). The Court held
only that the "EPA must ground its reasons for action or inaction in the statute."
Massachusetts v. EPA, 549 U.S. 497, 513 (2007). Here, the EPA is not introducing extra-
statutory policy concerns, as commenters suggest, but interpreting section 202(a)(1) in
light of Loper Bright and clarifying that the statute requires a nexus between contribution
and endangerment for the threshold for regulation to be satisfied.
As for Coalition, while the court said that the EPA is required to answer two questions
regarding contribution or endangerment, it did not speak directly to whether those
questions are to be answered completely separately or in a single causal chain such that
there is a nexus between the inquiries. In fact, the court seems to lend its support to the
position that the EPA is taking here. It states, "At bottom, § 202(a)(1) requires EPA to answer
only two questions: whether particular 'air pollution'—here greenhouse gases—'may
reasonably be anticipated to endanger public health or welfare,' and whether motor vehicle
emissions cause or contribute to' that endangerment." Coalition for Responsible
Regulation, 684 F.3d at 117 (emphasis added). This statement seems to recognize a nexus
between motor vehicle emissions and endangerment that would support the EPA's position
that severance of the two inquiries was improper.
EPA Summary of Comments
One commenter alleged that the EPA has long misread CAA section 202(a)(1) to require
pollutant specific endangerment findings. The commenter alleges that the statute instead
requires a finding that classes of new motor vehicles "cause or contribute" to dangerous air
pollution.
They say that insofar as the "primary rationale for proposed rescission" set forth in the
NPRM has as its starting premise the notion that CAA § 202(a)(1) requires the Administrator
to make a findingthat the emission of a specific air pollutant is responsible for creating
dangerous air pollution before the EPA is authorized to establish standards for that air
pollutant, the Agency's "primary rationale" is predicated on what would seem to be a rather
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obvious misreading of the statutory text. They say that because of this it is incumbent on
the EPA either to: (i) explain how its pollutant-specific interpretation of CAA section
202(a)(1) can be reconciled with how the statutory text actually reads; or (ii) just go with it,
make a last-minute face turn, and use the source-specific reading to your advantage; or (iii)
explicitly acknowledge that the plural form of "cause, or contribute to" in CAA section
202(a)(1) is simply a mistake.
EPA Response
The EPA disagrees with the commenter's read of section 202(a)(1) as it is not supported by
the statutory text and runs counter to the EPA's decades-long understanding of the
statutory scheme in addition to longstanding judicial precedent. Commenter's argument is
based on a grammatical technicality -i.e., the commenter argues that the phrase "cause,
or contribute" cannot refer to "the emission of any air pollutant" because the subject noun
that is doingthe "causing" or"contributing" must be something stated in the plural, and
that the only thing stated in the plural in this provision is "any class or classes of new motor
vehicles or new motor vehicle engines." But contrary to the commenter's claim, CAA
section 202(a)(1) is not a source category-focused provision. Section 202(a)(1) directs the
Administrator to prescribe standards "applicable to the emission of any air pollutant from
any class or classes of new motor vehicles or new motor vehicle engines, which in his
judgment cause, or contribute to, air pollution ..." For the reasons provided in the
preamble to the final action, the EPA has concluded that the best reading of section
202(a)(1) is that the EPA cannot regulate underthis section unless emissions of the air
pollutant by new motor vehicles and engines "cause, or contribute to, air pollution which
may reasonably be anticipated to endanger public health or welfare."
Moreover, the commenter's reading of section 202(a) would clearly lead to absurd results,
as it would require the EPA to promulgate regulations for any substance emitted by motor
vehicles, without any consideration of whether the substance contributes to air pollution
which endangers the public health or welfare. Relatedly, such a reading would give rise to
the constitutional concerns discussed in the section directly below in that it would
eliminate all limiting principles from the statutory text upon a single finding that a class of
motor vehicles contributes to emissions in any capacity - allowing from that point any and
all flavor of regulation of any substance emitted by the vehicle, presenting a nondelegation
problem. As discussed below and in greater detail in section 2.1.2.4.1 of this RTC, the
principle of constitutional avoidance would counsel against the commenter's preferred
interpretation.
The Supreme Court and other courts have long described section 202(a)(1) as conditioning
the exercise of the EPA's authority on a "judgment" that relates to whether an "air pollutant"
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causes or contributes to air pollution which may reasonably be anticipated to endanger
public health or welfare. See Massachusetts, 549 U.S. at 532 ("While the statute does
condition the exercise of EPA's authority on its formation of a 'judgment,' 42 U.S.C. §
7521 (a)(1), that judgment must relate to whether an air pollutant'cause[s], or contribute^]
to, air pollution which may reasonably be anticipated to endanger public health or
welfare'"); see also Coalition for Responsible Regulation, 684 F.3d at 117 ("This language
requires that the endangerment evaluation 'relate to whether an air pollutant 'cause[s], or
contribute^] to, air pollution which may reasonably be anticipated to endanger public
health or welfare'"). The EPA's longstanding interpretation of section 202(a)(1) is consistent
with these prior rulings and carries great weight in determining its best meaning. See Loper
Bright, 603 U.S. at 370 (noting the informed judgment of the executive branch may be
entitled to great weight depending upon "the thoroughness evident in its consideration, the
validity of its reasoning, its consistency with earlier and later pronouncements, and all
those factors which give it power to persuade, if lacking power to control") (quoting
Skidmore v. Swift, 323 U.S. 134,140 (1944)). Specifically, regulatory history demonstrates
that since the inception of section 202(a)(1), the EPA has interpreted the provision to
require endangerment findings on a pollutant-by-pollutant basis, even if we have analyzed
various classes of motorvehicles separately for various purposes. The EPA has never
issued a Title II regulation that lists permanent source categories, nor does Title II require
us to do so.
2.1.1.3.2 Cause or Contribute and Nondelegation Concerns
EPA Summary of Comments
Commenters reject the proposal's assertion that severing the endangerment and
contribution analysis results in absurd results and no limiting principle, raising
constitutional nondelegation concerns and absurd results.
They say that "reasonably anticipated to endanger public health or welfare" and "cause or
contribute" are the terms Congress chose to limit the EPA's discretion. They say that the
phrase "reasonably anticipated to endanger public health or welfare" and terms cause or
contribute have an extensive legislative history and history of implementation by the EPA.
They note that while these terms may be broad, they are clearly not unlimited. They say that
the EPA's application of these terms in specific cases has often been the subject of judicial
review and no case has indicated they are vague, unlimited, or require the EPA's proposed
interpretation here to avoid a standardless grant of power to the EPA.
Commenters state that the proposal's water vapor example does not support the EPA's
preferred reading of section 202(a)(1). They note that the EPA already addressed why water
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vapor would not be regulated under section 202(a)(1) in the 2009 Endangerment Finding.
They say that the EPA's contention rests on a basic misunderstanding of the science of
atmospheric hydrology. They say that emissions of water vapor from vehicles, or from any
human activity, do not meaningfully increase the volume or concentration of water vapor in
the atmosphere in any meaningful way, because water vapor has a very short lifetime in the
atmosphere of mere days, and anthropogenic water vapor emissions are many magnitudes
smaller than natural evaporation.
EPA Response
The EPA disagrees with commenters that regulating GHG emissions from new motor
vehicles in response to global climate change under section 202(a)(1) does not pose
nondelegation issues. The EPA does not disagree with commenters that the language of
section 202(a)(1) is, in fact, reasonably bounded and does not pose a nondelegation
problem. However, the Endangerment Finding - as well as these commenters - read the
statutory terms so broadly as to eliminate those constraints and create a nondelegation
problem. Under such reading, any "air pollutant" emitted by vehicles or engines at more
than de minimis volumes would trigger our authority and obligation to prescribe standards
so long as emission of the "air pollutant" from any and all sources globally contributes to
"air pollution" that, in turn, can be said to have any causal relationship to adverse impacts
on public health and welfare, broadly defined. By interpreting the statute to require a nexus
between contribution and endangerment, the EPA avoids the constitutional concerns
raised by the interpretation preferred by commenters and used in the Endangerment
Finding, in accordance with the canon of constitutional avoidance. For a comprehensive
discussion of the nondelegation issues raised by these commenters regarding the
threshold for regulation under CAA section 202(a)(1), see section 2.1.2.4.1 of this RTC
(Constitutional concerns and nondelegation doctrine).
The EPA disagrees that the agency's prior discussion regarding regulating water vapor
under section 202(a)(1) in the Endangerment Finding sufficiently addresses the
contentions that the Agency is now making regarding overbreadth, nondelegation, and
absurd results. The Endangerment Finding asserted that the EPA could regulate water
vapor but declined to do so because we thought it had a negligible effect on air pollution.
74 FR 66520. This discussion, in which the EPA said that we plan to further evaluate the
issue, clearly signals that we thought that the Agency did have the authority to regulate
water vapor based on the text of the statute. Id. The fact that the EPA has chosen not to
regulate a particular substance does nothingto respond to concerns that the
Endangerment Finding's interpretation of the statutory threshold for regulation lends itself
readily to absurd results.
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2.1.1.3.3 Threshold for Cause or Contribution
EPA Summary of Comments
Commenters argue that CAA section 202(a)(1) points to a low threshold for
regulation. Commenters allege that the proposal fails to show that GHGs from new motor
vehicles do not "contribute" to GHG pollution or endangerment under CAA section
202(a)(1). They argue that section 111 (b)(1) adds the word "significantly" to the phrase
"causes, or contributes to, air pollution" and that this term must also be considered
meaningful. They say the absence of this modifier to the term "contributes" in section
202(a)(1) indicates that the degree of contribution to endangerment required under 202(a)
is less than 111 (b)(1). They claim to conclude otherwise would violate a fundamental rule
of statutory construction - that when "engaged in the business of interpreting statutes we
presume differences in language like this convey differences in meaning." Henderson v.
Santander Consumer USA, Inc., 582 U.S. 79, 86 (2017).
Commenters argue that the EPA's position depends on eliminating the words "or
contribute" from the statute. They allege this is contrary to the fundamental tenet of
statutory construction that meaning should be given to every word in the statute. They say
"or contribute" as the threshold for regulation stands in contrast to other CAA regulation
thresholds that require substantive numeric thresholds before a source would be subject
to regulation. See CAA § 169 (PSD); CAA § 112 (HAPs). They note that in Catawba County,
the D.C. Circuit rejected the claim that "contribute" elsewhere in the CAA
necessarily connotes "significantly contributes" or "strictly causes," noting that
contribution may simply exacerbate a problem rather than cause it. They further analogize
to Bluewater Network, claiming the D.C. Circuit addressed "cause, or contribute" language
in CAA section 213 that mirrors that in 202(a)(1), and applying an "ordinary meaning"
analysis found "contribute" to mean "to have a share in any act or effect" or "to have a part
or share in producing" but that "standing alone, the term has no inherent connotation as to
the magnitude or importance of the relevant share in the effect" and "certainly does not
incorporate any 'significance' requirement."
Commenters note that when the EPA has made explicit endangerment and contribution
findings under section 202(a)(1), the EPA has determined relatively small emission
contributions satisfy the statute and merit regulation. They say that the EPA has
consistently found that even modest emission inventories not only "contribute" but
"significantly contribute" to dangerous air pollution under section 111. Specifically, they
argue, the statutory threshold for regulation is reasonable anticipation of endangerment.
They note the proposal mentions this in passing but does not meaningfully analyze the
terms in the context of Congressional intent.
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Commenters allege the Supreme Court clarified that the endangerment threshold does not
require proof of actual present harm, but rather a reasonable anticipation of future
endangerment based on scientific evidence, regarding the "may reasonably be anticipated
standard."
Commenters allege that the EPA assigns itself the role of determining when a regulatory
control program is appropriate and reasonable. They argue Congress did not assign this
role to the EPA- Congress decided that standards should be set if vehicle emissions
contributed to the air pollution and the air pollution endangers. They claim Congress gave
the EPA broad discretion on what standards to set, but Congress decided the threshold
question of whether the EPA was required to set standards. Commenters allege that the
EPA did not consider communities disproportionately harmed by climate change when
making the contribution determination.
Commenters allege that the US vehicles' contributions to GHG pollution are comparable to
or even greater than other pollution inventories that the EPA has found to "significantly
contribute" to national pollution problems under other provisions of the statute. For
example, they note, under CAA section 111, the EPA has consistently found that even
modest emission inventories not only contribute, but "significantly contribute" to
dangerous air pollution.
Commenters question the EPA's characterization of the Agency's prior practice of
determining that contribution meant any level above de minimis amounts and that
endangerment in turn meant any predicted negative impact on public health or welfare.
Commenters claim that the EPA failed to provide any evidence of this practice and details
how the EPA has historically evaluated evidence for making endangerment and
contribution determinations. They note that the EPA did not base its contribution decision
on a determination that motor vehicles contributed to GHG pollution because their
emissions levels were above de minimis levels. Rather, they say that the EPA found that
contribution from new motor vehicles is significant because their emissions are larger than
the great majority of emitting countries and constitute one of the largest parts of the US
emissions inventory.
EPA Response
First, the EPA would like to briefly discuss the various thresholds for regulation relevant
here and as raised by commenters. First, there is de minimis contribution, where
contribution is so insignificant such that it is implied in the statute that the EPA is not
intended to regulate such emissions. See Alabama Power v. Costle, 636 F.2d 323 (D.C. Cir.
1979); Ethyl Corp v. EPA, 541 F.2d 1 (D.C. Cir. 1976). Second, there is contribution - the
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standard in section 202(a)(1) - which requires something more than de minimis but is a
lower bar than significant contribution. Third, there is significant contribution, which as
commenters note is the standard required for regulation in section 111 (b).
What commenters misunderstand is that a comparison to the "significantly contribute"
standard in section 111 is incomplete, as they ignore the de minimis principle when using
this comparison to show a low threshold for regulation under section 202(a)(1 )'s
"contribute" standard.
Nor do Catawba County or Bluewater Network support commenters' preferred reading of
"contribute." Context here is important. First, in both Catawba County and Bluewater
Network, the D.C. Circuit is rejecting petitioners' arguments under Chevron that
"contribute" was unambiguous and must be interpreted in a certain way. See Catawba
County v. EPA, 571 F.3d 20, 39 (D.C. Cir. 2009); Bluewater Network v. EPA, 370 F.3d 1,13
(D.C. Cir. 2004). Because these cases upheld the EPA's interpretations of "contribute" as
reasonable under the Chevron framework, they are not particularly illuminative regarding
our interpretation here under a different section of the Act post-Chevron, where we are to
operate under the single best meaning of the statute.
Even taking Catawba County and Bluewater Network on their face, neither case disturbed
or considered - nor had reason to consider - the de minimis principle, which cabins
"contribute" on the other end. In other words, the court in these cases examined the
"ceiling" of the "contribute" standard in other CAA provisions by assessing the distinction
between contribution and significant contribution butdid notspeaktothefloorfor
regulation under this standard - namely the interplay between contribution and what would
be considered de minimis. It is the EPA's position here that if the Agency is appropriately
analyzing contribution and endangerment, such that both inquiries assess the same air
pollution. See the discussion in section 2.1.1.3.1 above, contribution from new motor
vehicles is de minimis.
Again, it is important to recognize that the Endangerment Finding erred by assessing
contribution and endangerment on two wholly distinct scales, such that there is no nexus
between the two inquiries. By severingthe inquiries, the Endangerment Finding masked the
fact that under one temporal scale contribution was de minimis (assessing contribution
from new motor vehicles in the US to total historic, present, and future GHG emissions in
the atmosphere), while under the other, the EPA would be unable to find endangerment
(annual domestic GHG emissions). In assessing contribution, the Endangerment Finding
used annual emissions to find contribution satisfied. The EPA does not dispute that when
looking only at annual GHG emissions, emissions from motor vehicles certainly contribute.
However, as discussed above, finding endangerment requires pulling in total global GHG
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emissions over a much broader time scale. Operating at this scale, annual motor vehicle
emissions are de minimis. Commenters alleging that the EPA has raised the bar for
regulation here inconsistently with how it regulates other pollutants and in other areas
miss this crucial point.
Further illustrating this point is the futility of regulating GHG emissions from motorvehicles
under section 202(a)(1). Even if we are to accept as given that "contribute" requires only
"exacerbating a problem" or "a share in any act or effect," as the Bluewater and Catawba
County courts suggest, GHGs from new motorvehicles cannot possibly meet even this low
threshold where regulating (or even eliminating) GHG emissions from motorvehicles has
no impact on global climate change. Bluewater Network v. EPA, 370 F.3d 1,13 (D.C. Cir.
2004); Catawba County v. EPA, 571 F.3d 20, 39 (D.C. Cir. 2009). In other words, emissions
cannot possibly contribute to air pollution in more than a de minimis manner where their
regulation would have essentially no impact on the dangers posed by that pollution.
EPA Summary of Comments
One Commenter alleges that the EPA does not make a "negative" contribution
determination for new motorvehicles. The commenters say the proposal does not provide
evidence to show that the risk from motor vehicles is not sufficient enough to warrant
regulation, only relying on a claim that removing light-duty vehicles would make no
measurable impact on global warming trends. They say the lawful way to rescind the 2009
determinations would require the proposal of a negative contribution and/or endangerment
determination. The proposed rescission, they claim, would return the Agency to the
position the Court rejected in Massachusetts, leaving an absence of a decision on whether
GHG emissions from new motorvehicles contribute to GHG air pollution that is or is not
reasonably anticipated to endanger public health or welfare.
EPA Response
The EPA disagrees with the commenter's contention that in order to rescind the
Endangerment Finding, we must make a "negative" contribution determination. First and
foremost, the EPA is making a determination that we lack the authority to regulate GHGs
under CAA section 202(a)(1). This would encompass standard setting, as well as making
determinations regarding contribution or endangerment as required underthe statute.
Even if we were to assume that commenters are correct that underthe framework of
section 202(a), if the EPA wants to properly cease regulation of a pollutant which it could
choose to regulate under section 202(a)(1) based on an analysis of contribution or
endangerment that we would have to support such a decision with a "negative"
contribution (or endangerment) finding, this would not apply here. Any statutory obligations
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under section 202(a)(1) regarding GHGs and their regulation necessarily must cease to
exist upon making this determination that the EPA lacks the authority to regulate them
under this provision.
2.1.1.3.4 Consideration of non-section 202(a) sources in the endangerment
analysis
EPA Summary of Comments
Commenters argue the EPA fails to explain how the Act's different regulatory approaches or
standards for regulation are relevant to the question of whether GHG emissions endanger
public health and welfare. For example, they state, the EPA fails to explain how "cause, or
contribute to" in section 202(a)(1) versus "causes, or contributes significantly to" in section
111 (b)(1 )(A) are relevant to the question of whether air pollution "may reasonably be
anticipated to endanger public health or welfare." They claim that various aspects of
potential control measures on sources other than motor vehicles are legally irrelevant to
determine whether emissions from motor vehicles contribute to air pollution that
endangers public health orwelfare.
EPA Response
The EPA agrees the controlling language for this rule is that in CAA section 202(a)(1), which
directs the Administrator to promulgate "standards applicable to the emission of any air
pollutant from any class or classes of new motor vehicles or new motor vehicle engines,
which in his judgment cause, or contribute to, air pollution which may reasonably be
anticipated to endanger public health orwelfare." 42 U.S.C. § 7521 (a)(1). But the agency
reads this provision to require a nexus between the finding of endangerment and the
contribution of specific emissions from the type of source (motor vehicles) addressed in
section 202(a)(1), consistent with the overall structure of the CAA. To the extent that the
EPA makes changes to regulations reliant on other statutory provisions, the EPA must
follow the relevant statutory language.
Within its structure, the CAA includes several provisions that require making particular
findings for regulating particular types of emission sources, including both mobile and
stationary sources. For example, CAA section 111 (b)(1 )(A) authorizes the EPA to regulate
emissions from listed categories of stationary sources if the Administrator determines
those sources emit air pollutants that "significantly contribute" to air pollution that
endangers public health orwelfare. 42 U.S.C. § 7411(b)(1)(A), (a)(1), (b)(1)(B). Other
provisions in the CAA similarly set out distinct standards for the EPA's determination of
whether to regulate and distinct ways to regulate the particular emissions and types of
sources of emissions that the provision addresses, such as vehicles in use or aircraft
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engines. CAA section 115 separately addresses when and how to respond to international
emissions that impact the United States. Consideringthat Congress made specific
decisions in each such provision of the CAA with regard to the standard for whether to
regulate and specified how the EPA is to regulate specific emissions and sources of
emissions if that standard is met, CAA section 202 is best read in the context of this
structure to require specific findings of endangerment with regard to the particular class or
type of emissions and sources that this provision empowers the Administrator to regulate
in a particular manner.
The Endangerment Finding is not supported by this best reading of the CAA because it
effectively aggregated the total GHG emissions coming from all of these various distinct
sources within the United States, as well as from all international sources, along with the
sources regulated under CAA section 202, and then found that this combination of
emissions met the particular standard for regulating vehicles under section 202. But for
these emissions from other types of sources, the Endangerment Finding did not reflect the
requisite determinations under other applicable provisions of the CAA for any of those
other types of sources or implement the different regulatory tools that Congress authorized
for those particular types of emissions or sources based on the requisite finding.
EPA Summary of Comments
Commenters note that Congress deliberately structured the CAA so that regulation of
different source categories works in concert to reduce pollution levels nationwide. They
claim requiring separate Endangerment Findings for each regulatory program fragments
this scheme and frustrates the cumulative reduction of pollutants that the Act envisions.
Commenters allege legislative history reveals a purpose of CAA section 202(a)(1) is to
assure "consideration of the cumulative impacts of all sources of a pollutant... not just
the extent of the risk of the emissions from a single source or class of sources." Based on
legislative history, they claim Congress "intend[ed] to require the [EPA] to consider all
sources of the contaminant which contribute to air pollution," not just "source categories
that emit[] enough pollution to independently cause health harms."
EPA Response
That Congress intended the various CAA programs to work in concert to address a
nationwide air pollution problem does not justify overlooking that the CAA contains distinct
provisions that have variations in the particular standards for whether and how to regulate
specific types of sources to address that common problem. See the discussion in the prior
response. The deliberate choices reflected in distinct parts of the CAA would be frustrated
if the Act were read to allow the EPA to make a sweeping finding to regulate all types of
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sources based on the standard for whether to regulate one type or source or to regulate
one type of source based on the combined emissions of several, distinct types of sources.
This would nullify the choices made in the Act on whether to regulate particular types of
sources and how to regulate such sources if that standard is met. This clear structure in the
CAA itself cannot be overcome by the legislative history cited by the commenter. See Exxon
Mobil Corp. v. Allapattah Servs., 545 U.S. 546, 568 (2005) (legislative history or other
extrinsic material may be used as an aid in statutory construction "only to the extent they
shed a reliable light on the enacting Legislature's understanding of otherwise ambiguous
terms").
2.1.1.3.5 Consideration of six "well-mixed" GHGs together as an air
pollutant
EPA Summary of Comments
Commenters reject the proposal's claim that it was both improper and material for the
Endangerment Finding to consider six "well-mixed" GHGs. Commenters note that "air
pollutant" in section 302(g) of the CAA is defined as "any air pollution agent or combination
of such agents." They also say that the six GHGs addressed in the Endangerment Finding all
share relevant common characteristics and therefore the agency was justified in
considering them as part of a collective group. Commenters state that the six GHGs each
persist in the atmosphere for multiple years, long enough to become evenly distributed
(well-mixed) in the global atmosphere, and that the pollutants each warm the atmosphere
by absorbing outgoing infrared radiation that otherwise would escape to space.
Commenters note that the EPA's 2009 approach is consistent with the EPA's longstanding
approach to addressing harm from other air pollutants. They say that the EPA assesses the
harms of nitrogen oxides nitrites, nitrates, nitrogen acids, ammonia, and n-nitroso
compounds collectively, even though the pathways through which these various molecules
cause harm are more diverse than GHGs, and that the EPA assesses sulfur oxides, and
VOCs collectively. Commenters also say that like GHGs, these collections are emitted by a
variety of sources both domestically and internationally.
Commenters note that each and all of these gases considered separately or collectively is
sufficient to satisfy the endangerment inquiry. They say that the EPA's suggestion that the
outcome of the endangerment inquiry would change if the gases were considered
separately is implausible, where vehicles are the largest source of domestic C02 emissions
- 28% per the EPA's own data in 2022 - and emit HFCs, some of the most potent GHGs.
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Commenters also note that Congress has itself grouped these GHGs together in the
renewable fuels program, 42 U.S.C. § 7545(o)(l)(G), and several CAA provisions added by
the IRA. E.g. 42 U.S.C. § 7433(d)(2).
EPA Response
These commenters misunderstand and mischaracterize the EPA's proposal discussion on
the six "well-mixed" GHGs and how it factors into the cause and contribute and
endangerment analysis in CAA section 202(a)(1). The EPA is not making assertions that the
Agency cannot ever consider pollutants in collective groups based on their characteristics,
that these pollutants do not have things in common, nor making claims about how air
pollutant is defined as it relates to this topic. The EPA was merely calling attention to
another way in which the severing of the endangerment and contribution analyses in the
2009 Endangerment Finding led to a questionable mismatch - a comparison of apples and
oranges - of the relevant data for the two separate analyses. This again points to the reality
that the two analyses should instead be one analysis in one causal chain as CAA section
202(a) is written, and is supported by principles of causation and proximate cause. See,
e.g., Bank of Am. Corp. v. City of Miami, 581 U.S. 189, 201 (2017); Lexmark Int'l, Inc. v. Static
Control Components, Inc., 572 U.S. 118,132 (2014); Univ. of Tex. Sw. Med. Ctr. v. Nassar,
570 U.S. 338, 347 (2013); City of Oakland v. Wells Fargo & Co., 14 F.4th 1030 (9th Cir. 2021)
(en banc).
While the six "well-mixed" GHGs may or may not be relevant in considering the question of
whether GHGs endanger public health or welfare if that question is isolated (which it
should not be), when we consider the full scope of CAA section 202(a) including the
"contribution" and "endangerment" parts of the analysis, it is rather odd to consider
multiple pollutants - PFCs and SF6-that are asserted to have many times the global
warming potential of C02 and yet are not even relevant to vehicle emissions for the
purposes of endangerment, but that those pollutants are necessarily excluded from the
contribution analysis. This is just another point that supports the best reading of the Act as
laid out in this preamble.
Additionally, it is worth noting that the pollutants grouped together also have many
significant unarguable differences from one another. For example, C02 is essential to life
on earth, emitted by humans, absorbed by the environment, and critical to natural
ecosystems. While PFCs, for example, are synthetic man-made chemicals that often are
emitted during manufacturing processes, are potent and are among the longest lasting
GHGs emitted by human activities. The EPA carefully considers how each pollutant affects
public health and welfare and dutifully reassesses that information as time goes on and
science develops, in orderto responsibly craft such findings and regulations. Notingthe
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fact that these pollutants have significant differences is simply part of executing that role
responsibly.
2.1.1.3.6 The use of existing vehicle data when conducting a cause or
contribute analysis
EPA Summary of Comments
Commenters allege that the proposal's claim that the Endangerment Finding read "new"
out of the statute is baseless. They say that the proposal's claim that considering existing
vehicle data rather than projecting emissions was improper and "increased the absolute
contribution figure by orders of magnitude" is baseless and ignored the EPA's own analysis.
Commenters say that in 2010, total C02 emissions from gasoline and diesel fueled motor
vehicles were 1.515 billion metric tons, compared to 1.479 billion in 2024, a 2%
difference. They say that the EPA in 2009 explained why the surrogate used is a reasonable
way to determine emissions from new motor vehicles in the context of making contribution
and endangerment findings. Commenters also say that the EPA at the time explained that
the uncertainty and potential difference in emissions was not expected to have any
substantive impact on the contribution determination. Commenters argue that the
proposal does not engage with this analysis from the past.
EPA Response
The EPA disagrees with commenters' claims. The EPA's decision to consider existing
vehicle data in the Endangerment Finding was flawed, because CAA section 202(a)(1) is
very clear that they analysis of contribution is to be limited to "new motor vehicles or new
motor vehicle engines" in the United States. Just because it may have been difficult to
disaggregate emission data between existing and new vehicles does not mean the EPA can
choose to ignore statutory language as we see fit.
Commenters claim that there is a 2% difference in total C02 emissions from gasoline and
diesel fueled motor vehicles from 2010 to 2024, and attempt to use this data point to show
that it doesn't matter whether the EPA only considered new vehicles or considered all
existing vehicles in 2009. The EPA finds this two percent estimate from commenters to be
consistent with our assessment that the C02 emissions from transportation have
decreased three percent between 2018 and 2022.8 However, the conclusions drawn by the
commenters are not supported by this value. In fact, it further demonstrates the difference
between the impact of newvehicles compared to the entire fleet of vehicles on C02
8 U.S. EPA Fast Facts U.S. Transportation Sector Greenhouse Gas Emissions 1990 -2022.EPA-420-F-24-
022.May2024.Page 3.
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emissions. Because the emission standards apply only to newvehicles, the EPA typically
analyzes the impact of the emissions on a per-vehicle basis by comparing emissions from a
new vehicle subject to the standards to a vehicle that was not subject to the standards. The
2010 light-duty rule set GHG emission standards starting with the sale of MY 2012 vehicles
and those standards were projected to decrease the per-vehicle C02 emissions by 15
percent for MY 2016 vehicles.9 Similarly, in the HD GHG Phase 1 rule the EPA set GHG
emission standards beginning in MY 2014 and projected per-vehicle emission reductions
between six and 23 percent for MY 2017 vehicles.10 If there was no difference between the
fleet-level contribution and the contribution from only newvehicles, then we would have
expected the reduction of C02 emissions from transportation fleet to be over 15 percent,
yet we only see a 2 to 3 percent reduction. This is partly because the contribution of C02
emissions from new vehicles is significantly less than for the fleet overall.
Relatedly, the Endangerment Finding assumed the contribution from vehicles would
remain constant over time, however, newer vehicles and engines are more efficient and
emit less GHG emissions nowthan they did in the 2009 analysis, therefore one would
expect the contribution from vehicles today to be less than what was projected in 2009,
which is another factor that shows the contribution analysis at the time was flawed. Finally,
while commenters may try to frame these data points differently or argue about what they
show, they cannot disagree with the clear statutory text which commands this analysis.
CAA section 202(a)(1) is clearthat"new motor vehicles or new motorvehicle engines" are
the only sources covered by the CAA section 202(a) authority, not the entire transportation
sector.
2.1.1.3.7 Consideration of vehicle classes individually when making Cause
or Contribute and Endangerment findings under section 202(a)(1)
EPA Summary of Comments
Commenters allege that it was proper forthe Endangerment Findingto consider all classes
of CAA section 202(a) sources together. Commenters state that it was supported by the
statutory text and legislative history, which reveals a purpose of CAA section 202(a)(1) is to
assure "consideration of the cumulative impacts of all sources of a pollutant... not
just the extent of the risk of the emissions from a single source or class of
sources." Commenters allege that it was proper forthe Endangerment Findingto consider
all classes of CAA section 202(a) sources together. Commenters state that it was
supported by the statutory text and legislative history, which reveals a purpose of CAA
9 75 FR 25331.The projected fleet average GHG target for Light-duty vehicles was reduced from 295 g C02/mi
in MY 2012 to 250 g C02/mi in MY 2016.
10 76 FR 57116 and 57234
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section 202(a)(1) is to assure "consideration of the cumulative impacts of all sources of a
pollutant... not just the extent of the risk of the emissions from a single source or class of
sources."
EPA Response
The EPA is not clear on why commenters are making this point based on what the EPA
proposed. The proposal did not argue that the classes of section 202(a) sources needed to
be separated. That said, while the EPA did not propose that it is necessarily incorrect to
consider classes of vehicles togetherwhen making findings in general, it may be best that
they are considered separately for GHG emissions as the language within CAA section
202(a)(1) distinguishes between classes of new motor vehicle and thus implies that it may
be appropriate for the Administrator to make an endangerment finding for one class of new
motorvehicle or new motorvehicle engine but not for another even forthe same air
pollutant. And regardless of whether they are considered separately or together, either way
they do not reach the level necessary to justify an Endangerment Finding. Additionally, the
Endangerment Finding considered not only emissions from all classes of new motor
vehicles, but also from existing vehicles, in finding contribution. This is just another way in
which the Endangerment Finding's analysis was flawed and the severance of the
contribution and endangerment questions affected the result. Commenters should see the
many other sections in the RTC and preamble where we explain the mismatch in
information produced by severing the two questions. Additionally, the legislative history
cited by commenters is misconstrued here, and is just as easily read as consistent with the
idea that the EPA must make findings for each vehicle class, so long as the EPA is assessing
the air pollution as a whole when identifying endangerment. Not to mention, as a general
matter, and as discussed in RTC section 2.1.1, legislative history cannot trump the
statutory text and is not informative on its face. See NLRB v. SWGen., Inc., 580 U.S. 288,
307 (2017); Milnerv. Dep'tofthe Navy, 562 U.S. 562, 572 (2011).
2.1.1.3.8 Considering carbon leakage in the Cause or Contribute and
Endangerment Analyses
EPA Summary of Comments
Commenters argue that issues of carbon leakage are beyond the scope of the statutorily
mandated questions of (a) endangerment and (b) cause or contribute. They state that the
question of carbon leakage has absolutely no bearing on the transportation sector, where
the EPA sets standards for emissions caused by using all new vehicles sold in the United
States. Commenters argue that leakage concerns do not apply because limits to emissions
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of vehicles driven in the U.S. cannot encourage the transfer of miles driven to other
countries.
EPA Response
Commenters misunderstand the context in which the EPA discussed carbon leakage. The
EPA included the concept of carbon leakage in the proposed rule preamble to solicit views
on the phenomenon and its relevance to the analysis that the 2009 Endangerment Finding
did not perform, that is, of the regulatory consequences and obligations that flow from
making an affirmative determination. This is because the Endangerment Finding took the
novel step of defining the relevant "air pollution" as global in nature. However, the EPA is
not finalizing anything related to carbon leakage, and therefore these comments are
outside of the scope of the final action.
2.1.2 Lack of Clear Congressional Authorization
2.1.2.1 Applicability of the Major Questions Doctrine to the Endangerment
Finding
EPA Summary of Comments
Some commenters stated that the Endangerment Finding presents a major question and
that the EPA lacks clear congressional authorization to issue it. They argued that by seeking
to resolve significant aspects of the debate on climate change - including anthropogenic
causes and government solutions -the Endangerment Finding put itself on the same plane
of importance as NFIB v. OSHA, 595 U.S. 109 (2022) and Gonzales v. Oregon, 546 U.S. 243
(2006). Commenters noted that some might object that the proper level of analysis for the
major questions doctrine isn't climate change, but the EPA's section 202(a)(1) GHG
emission standards regulating automotive exhaust. According to these commenters,
thatlevel of specificity for determining when the doctrine applies would be too exacting.
EPA Response
The EPA agrees with the commenters that the major questions doctrine applies to the
Endangerment Finding. Through the Endangerment Finding, the EPA established the legal
foundation to regulate GHG emissions under CAA section 202(a)(1). The Endangerment
Finding automatically triggered a statutory obligation to regulate GHG emissions, and the
regulatory consequences that ensued were both foreseeable and in fact foreseen by the
EPA. See 73 FR 44354, 44355 (July 30, 2008) ("[l]f EPA were to regulate greenhouse gas
emissions from motor vehicles underthe Clean Air Act, then regulation of smaller
stationary sources that also emit GHGs - such as apartment buildings, large homes,
schools, and hospitals - could also be triggered. One point is clear: The potential
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regulation of greenhouse gases under any portion of the Clean Air Act could result in an
unprecedented expansion of EPA authority that would have a profound effect on virtually
every sector of the economy and touch every household in the land ... the ANPR
demonstrates the Clean Air Act, an outdated law originally enacted to control regional
pollutants that cause direct health effects, is ill-suited for the task of regulating global
greenhouse gases. Based on the analysis to date, pursuing this course of action would
inevitably result in a very complicated, time-consuming and, likely, convoluted set of
regulations."); 74 FR 66496, 66502 (Dec. 15, 2009) ("Once the final affirmative contribution
and Endangerment Findings are made, EPA has the authority to issue the final emissions
standards for new light-duty motor vehicles"). These foreseeable consequences from the
Endangerment Finding include the obligation to regulate motor vehicles, that the
regulations would need to contain very stringent standards to have any even conceptually
possible impact on the problems identified, and that the EPA would need to expand the
implications of the Endangerment Finding by regulating stationary sources through
permitting, see UARG, and through actions under CAA section 111, see West Virginia. The
Endangerment Finding triggers the major questions doctrine because the finding itself
triggered foreseeable and legally mandatory regulatory duties.
In West Virginia, the Clean Power Plan emission guidelines did not directly impose billions
in costs on industry or force a generation shift; there were several foreseeable steps in the
causal chain. First, the EPA issued regulations determiningthe amount of pollution
reduction to be achieved, second, states submitted plans containingthe emissions
restrictions they intended to implement and enforce in order not to exceed the permissible
level of pollution established by the EPA, the EPA approved or disapproved the plans, and
then the plans (or Federal plans) satisfied the requirements of CAA section 111 and were
enforceable against existing sources. Similarly here, the EPA issued the Endangerment
Finding, was thereupon required to prescribe standards under CAA section 202(a),
triggered stationary source permitting requirements, and was required to issue regulations
under section 111, all as predicted in the 2008 ANPRM.
Further, the vehicle standards issued by the EPA separately and independently violate the
major questions doctrine as the EPA's rulemakings have not been limited to emission
standards as anticipated in Massachusetts, but instead reflect an increasing trend toward
mandating a transition toward EVs for virtually all classes of LD, MD, and HD vehicles, i.e.,
from one type of fuel (gasoline/diesel) to another (electric), very much like West Virginia.
The EPA's unprecedented and transformative emissions standards were the inevitable and
foreseeable result of the Endangerment Finding. Because of the global nature of the
problem identified in the Endangerment Finding, only the most severe reductions in GHG
emissions were ever going to approach having any arguable impact on the dangers
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identified in the Endangerment Finding. See, e.g., Biden v. Nebraska, 600 U.S. All (2024)
(concluding that the Secretary of Education's loan forgiveness plan that would have
resulted in student loan cancellation for millions of borrowers violated the major questions
doctrine); In re MCP, 2024 U.S. App. LEXIS 19815 (6th Cir. 2024) (concluding that FCC's
classification of broadband providers as common carriers that would subject the providers
to future regulation likely presented a major question given the importance of broadband to
modern life, national security, and public safety). As early as the EPA's first light-duty
vehicle rule in 2010, the Agency relied on and knew its regulation would lead to increased
EV production. See 75 FR 25324, 25332 (May 7, 2010) ("NHTSA's and EPA's technology
assessment indicates there is a wide range of technologies available for manufacturers to
consider in upgradingvehicles to reduce GHG emissions and improve fuel economy.... As
noted, these include improvements to the engines such as use of gasoline direct injection
and downsized engines that use turbochargers to provide performance similar to that of
larger engines, the use of advanced transmissions, increased use of start-stop technology,
improvements in tire rolling resistance, reductions in vehicle weight, increased use of
hybrid and other advanced technologies, and the initial commercialization of electric
vehicles and plug-in hybrids.... All of these technologies are already available today, and
EPA's and NHTSA's assessments are that manufacturers will be able to meet the standards
through more widespread use of these technologies across the fleet.").
EPA Summary of Comments
Some commenters also contended that the major questions doctrine is more appropriately
assessed with respect to both the Endangerment Finding and the specific set of standards
that result from the Endangerment Finding, and not to the Endangerment Finding in
isolation. Commenters asserted that even if the 2024 standards were unauthorized under
the Endangerment Finding, those particular standards might be unlawful and that the
nature and stringency of that most recent set of standards was not dictated by the
Endangerment Finding itself. Other commenters supported the EPA's second, more
targeted proposed application of the major questions doctrine, which would constrain but
not eliminate the EPA's authority to regulate GHGs under CAA section 202(a) by preventing
the Agency from effectively mandating ZEVs as a purported emissions control measure for
motor vehicles powered by internal combustion engines.
EPA Response
Commenters overread UARG and West Virginia in their assertions that the major questions
doctrine can only apply to vehicle standards and not to the Endangerment Finding. In
UARG, the Court explained that it would defer to the EPA's application of BACT under
Chevron because the statute did not categorically prohibit interpreting the BACT provision
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to apply to GHGs emitted by "anyway" sources. Chevron is no longer an appropriate
interpretive methodology. Additionally, the Court in UARG essentially applied the major
questions doctrine in tandem with Chevron Step 2 - whereas more recent Supreme Court
cases applied it before considering whether Chevron deference would apply and noted the
major questions doctrine may apply even if there is a plausible statutory basis for the
agency's assertion, see, e.g., West Virginia, 597 U.S. at 723, an approach which is more
appropriate in light of Loper Bright.
Further, the analogy to UARG is inapplicable. In UARG, the Court said that the statute
allowed applying BACT to "anyway" sources because BACT "is required 'for each pollutant
subject to regulation under this chapter' {i.e., the entire Act)... the necessary judgment
has already been made by Congress." 573 U.S. at 331. In other words, the Court found that
the statute allowed such application and that although some particular applications may
be unlawful, others may be lawful. Here, whether the Endangerment Finding is unlawful is
that predicate question: whether Congress made the necessary judgment in CAA section
202(a)(1) that GHGs are subject to regulation as air pollution that endangers public health
or welfare. The correct answer is it did not, and even if it did, the EPA's use of that authority
to cause an increasing transition to EVs for virtually all classes of LD, MD, and HD vehicles
demonstrates the Endangerment Finding's overbreadth and why the 2024 vehicle
standards violate the major questions doctrine within the exercise of that authority. As to
West Virginia, commenters also overread the opinion and some assert issues with the
EPA's interpretation of that case. The Court stated that the question before it was whether
the particular BSER in the Clean Power Plan was within the scope of authority granted to
the EPA in CAA section 111 (d). The Court did not decide the separate question of whether
section 111 authorizes the regulation of GHG emissions; i.e., the Court was not reviewing
whether the Clean Power Plan and 2015 NSPS were valid under the major questions
doctrine based on the EPA's assertion of authority to regulate GHGs in the first instance.
EPA Summary of Comments
Some commenters argued that the EPA asked the wrong interpretive question in its major
questions doctrine analysis, stating that the correct inquiry is whether the major questions
doctrine prohibits the EPA from regulating GHGs under CAA section 202(a)(1) at all.
Commenters contended that analysis under the major questions doctrine does not ask
whether an assertion of authority, like the Endangerment Finding, has the potential to lead
to other actions which are themselves extraordinary, but rather focuses on the asserted
authority itself. The major questions doctrine would only apply to the Endangerment
Finding, they contended, if every possible regulation promulgated based on it would be
problematic. Commenters further argued that nothingthatthe EPAdid inthe
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Endangerment Finding placed a mandatory duty on the agency to adopt the said-to-be
exceedingly stringent standards that the EPA promulgated in 2024. Commenters stated
that the Endangerment Finding is not an assertion of authority; it is a scientific assessment.
Some commenters cited UARG, 573 U.S. at 332 (for the proposition of refusing to extend
major questions analysis to "potential" regulations that could result from the asserted
authority, because the asserted authority would not necessarily "lead to an unreasonable
and unanticipated degree of regulation"), and West Virginia, 597 U.S. at 734-35, to support
this argument.
EPA Response
The EPA views the appropriate major questions doctrine inquiry as whetherthe asserted
authority-here, the authority to regulate GHG emissions from vehicles - is a major
question as defined by Supreme Court precedent. The EPA does not need to demonstrate
whether each standard issued under that assertion would also be a major question,
particularly since the agency previously impermissibly divorced the finding from the
standards. It is appropriate to apply the major questions doctrine to the Endangerment
Finding, regardless of the specific standards that the EPA may promulgate as a result,
because the finding meets the criteria for presenting a major question. The Agency cannot
insulate itself from the major questions doctrine by severing essential steps in the
regulatory process. For example, in Biden v. Nebraska, the agency action found unlawful by
the Supreme Court would not have been transformed into a lawful action had the agency
first issued a finding that the circumstances constituted a "national emergency" and then
later, in a separate series of actions, forgiven student loans for various groups of individuals
on that basis. See 600 U.S. 477, 486, 494 (interpreting 20 U.S.C. § 1098bb etseq.); id. at
499-500 ("The Secretary's comprehensive debt cancellation plan cannot fairly be called a
waiver - it not only nullifies existing provisions, but augments and expands them
dramatically. It cannot be mere modification, because it constitutes effectively the
introduction of a whole new regime. And it cannot be some combination of the two,
because when the Secretary seeks to add to existing law, the fact that he has "waived"
certain provisions does not give him a free pass to avoid the limits inherent in the power to
"modify." However broad the meaning of "waive or modify," that language cannot
authorize the kind of exhaustive rewriting of the statute that has taken place here.")
(internal citations and quotes omitted).
The EPA also disagrees with commenters' characterization of the Endangerment Finding as
a scientific assessment unrelated to any assertion of authority. As the Endangerment
Finding itself acknowledged, the EPA was required to issue emissions standards if it made
an affirmative finding. 74 FR 66496, 66502 ("EPA will issue final emission standards for new
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motor vehicles only if affirmative findings are made concerning contribution and
endangerment... EPA has consistently made it clear that the issuance of new motor
vehicle standards requires and is contingent upon satisfaction of the two-part
endangerment test"); Id. at 66507 ("If EPA makes an affirmative finding, then it shall set
emissions standards applicable to emissions of such air pollutants from new motor
vehicles."); 75 FR 31514, 31519 (Jun. 3, 2010) ("These findings ... do not themselves
impose any requirements on industry or other entities. However, they were a prerequisite to
finalizing the GHG standards for light-duty vehicles."). The EPA employed CAA section
202(a), a findingthat would result in subsequent regulations being issued. The EPA
acknowledged in the 2009 Endangerment Finding that it typically issued findings and
standards together, 74 FR 66501 (Dec. 15, 2009), and even in asserting it had discretion to
sever the two in 2009, it knew it would be obligated to issue standards and subsequent
regulations. The Supreme Court has noted that major questions cases "have arisen from all
corners of the administrative state." Biden v. Nebraska, 600 U.S. 477, 505 (2023) (citing
West Virginia, 597 U.S. at 721). Therefore, nothing prohibits its application to the
Endangerment Finding even if the Endangerment Finding were to be considered a scientific
assessment that did not directly impose regulatory standards.
EPA Summary of Comments
One commenter argued that if the EPA insists that West Virginia applies to the rescission of
the Endangerment Finding, it will have to go to Congress to pursue a modification of the
CAA and section 202(a).
EPA Response
The EPA disagrees with the commenter's assertion that Congress would need to amend
CAA section 202(a) in order for the EPA to apply the major questions doctrine to the
Endangerment Finding. The doctrine applies to the EPA's implementation of the statute as
written for the reasons discussed in the final action preamble and elsewhere in this RTC.
EPA Summary of Comments
Another commenter contended that the Endangerment Finding is not premised on the
agency being authorized to decide the U.S.'s response to global climate change concerns
but was a valid exercise of authority granted by Congress through the CAA to regulate
motor vehicle emissions. Congress, commenters argued, may take up the larger question
of climate change and the appropriate role that may be served by the U.S. in combatting a
global phenomenon. Commenters stated that in the context of the Endangerment Finding,
the EPA did not take up such matters as treaties, UN resolutions, international sanctions,
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revamping energy, power generation or transportation here or abroad, regulation of agri-
business emissions or attempt to decide the Nation's response to global climate change by
any of the myriad possible responses to the effects of GHGs. Commenters stated that the
agency acted within the finite scope of its clear authority to regulate those sources of
pollution over which it has jurisdiction.
EPA Response
The EPA disagrees with the commenter. As discussed in the final action preamble and
elsewhere in this document, the EPA lacks statutory authority under CAA section 202(a)(1)
to regulate GHG emissions from motor vehicles in response to global climate change
concerns.
EPA Summary of Comments
Some commenters stated that the major questions doctrine is a tool of statutory
interpretation, and as the Supreme Court has recognized, stare decisis carries enhanced
force for statutory interpretation decisions, including after a change in interpretive
methodology (some citing to Kimble v. Marvel Ent., LLC, 576 U.S. 446 (2015)). Accordingly,
commenters argued, even if West Virginia can be considered a change in interpretive
methodology since Massachusetts, the holding that CAA section 202 permits regulating
GHG emissions remains binding. Further, they argued that even accepting the EPA's
implicit premise that the major questions doctrine did not exist when Massachusetts was
decided, Massachusetts still forecloses the EPA's major questions doctrine argument now.
EPA Response
The EPA disagrees with this commenter's characterization of the holding in Massachusetts
as discussed in sections 2.1.1.1.7 and 2.1.2.1.1.
2.1.2.1.1 EPA's ability to regulate GHG emissions from motor vehicles in
response to global climate change concerns presents a major
question
EPA Summary of Comments
Commenters argued that the Court in Massachusetts made some specific arguments as to
why the authority to regulate emissions from vehicles was not a major issue. In comparing
this authority to the issues in FDA v. Brown and Williamson, the Court did not think that the
authority was as great as the FDA banning tobacco products. The importance of cars
compared to tobacco products is not even close. Further, regardless of a ban, the scope
and effect of vehicle standards go way beyond any type of tobacco ban.
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EPA Response
As addressed elsewhere in this document, the EPA agrees that the trajectory of its
rulemakings regulating GHG emissions from motor vehicles has proceeded in a way that
the Court could not have anticipated when it decided Massachusetts.
EPA Summary of Comments
Some commenters contended that both legislative history of the Act, enactments of other
laws with GHG provisions for incentive, grant, and similar programs, and various terms
contained in 202(a)(1) and the Act's definitions to claim that Congress clearly intended to
address global climate change concerns. Thus, many of these comments say that the
Endangerment Finding does cannot therefore pose a major question. Comments assert
that the Act, taken as a whole, cannot pose a major question because Congress clearly
sought to address GHGs.
Some commenters further argued that West Virginia v. EPA effectively invalidated
Massachusetts. They argued that in Massachusetts, SCOTUS attempted to divine
authorization for the EPA to regulate GHG emissions under the CAA because no express
authorization has ever existed and that no more fact or law is needed to rescind the
Endangerment Finding.
EPA Response
As discussed in the final action preamble and elsewhere in this document, the EPA views
West Virginia as providing additional, relevant guidance on statutory interpretation and the
breadth of agency authority. See section 2.1.1.1.7 for additional discussion of
Massachusetts v. EPA.
EPA Summary of Comments
Other commenters argued that Massachusetts v. EPA forecloses the EPA's application of
the major questions doctrine. They argued that the major questions doctrine only applies
where the statutory text is ambiguous and that since Massachusetts held that the relevant
statutory text is unambiguous, it cannot apply. Some commenters also said that
Massachusetts did not consider the major questions doctrine because the Court found a
clear congressional delegation to the EPA to promulgate standards for pollutants
contributing to climate air pollution. Others said that a final action premised on broader
arguments that the CAA does not allow for the issuance of an Endangerment Finding for
GHGs, or for the setting of any GHG emission standards for new mobile sources, could
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potentially be challenged as being inconsistent with Massachusetts and so could come
with increased litigation risks and uncertainty.
EPA Response
The EPA disagrees with the assertion that Massachusetts precludes our ability to apply the
major questions doctrine to the Endangerment Finding. As discussed in RTC section
2.1.1.1.7, Massachusetts addressed the CAA-wide definition of "air pollutant," and did not
squarely address whether CAA section 202(a)(1) is unambiguous. The Supreme Court's
decision in Massachusetts straddled a transitional period regarding the appropriate
standards for judicial review of an agency's statutory interpretation and understandings of
agency authority. The breadth of agency discretion, and the question of whether Congress
reserves major policy questions for itself, were sharply disputed. Judicial decisions in the
intervening fifteen years have significantly clarified the law in both respects. In Loper
Bright, the Supreme Court expressly overturned the Chevron doctrine of deference to
agency statutory interpretation, ruling that statutes "have a single, best meaning" that may
be informed, but not directed, by Executive Branch practice. 603 U.S. at 400-01. And in
West Virginia, the Supreme Court built upon its prior decisions in UARG and Brown &
Williamson, among others, by confirming that an agency must have more than "a colorable
textual basis" to claim authority to decide major questions of policy that Congress would
generally reserve for itself in the first instance. 597 U.S. at 723. For additional discussion of
Massachusetts, see this RTC at 2.1.1.1.7.
In Massachusetts, the Court identified at least two critical components of its decision in
Brown & Williamson that it thought had no counterpart in Massachusetts. Massachusetts,
549 U.S. at 531. First, the Court thought it was unlikely Congress meant to ban tobacco
products, which the Food, Drug, and Cosmetic Act would have required if they had been
classified as "drugs" or "devices." The Court further believed that:
[l]n contrast, EPA jurisdiction would lead to no such extreme measures. EPA
would only regulate emissions, and even then, it would have to delay any
action 'to permit the development and application of the requisite technology,
giving appropriate consideration to the cost of compliance'. However much a
ban on tobacco products clashed with the 'common sense' intuition that
Congress never meant to remove those products from circulation, there is
nothing counterintuitive to the notion that EPA can curtail the emission of
substances that are putting the global climate out of kilter.
Id. (citations omitted) (emphasis in original). As discussed in the final action, contrary to
the Supreme Court's expectations, the EPA's subsequent rulemakings have not been
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limited to simply regulating GHG emissions as could have been anticipated in
Massachusetts, but instead reflect an increasing trend toward mandating a
transition toward EVs for virtually all classes of LD, MD, and HD vehicles. See RTC below for
discussion of the trajectory of the EPA's vehicle standards.
Second, the Massachusetts Court distinguished Brown & Williamson by noting its reliance
on "an unbroken series of congressional enactments that made sense only if adopted
'against the backdrop of the FDA's consistent and repeated statements that it lacked
authority under the [Food, Drug, and Cosmetic Act] to regulate tobacco.' We can point to
no such enactments here: EPA has not identified any congressional action that conflicts in
any way with the regulation of greenhouse gases from new motor vehicles. Even if it had,
Congress could not have acted against a regulatory 'backdrop' of disclaimers of regulatory
authority." Id. (citations omitted). Since Brown & Williamson was decided, the Court has
clarified the relevant considerations to determine political significance under the major
questions doctrine, such as the "importance of the issue, along with the fact that the
same basic scheme EPA adopted has been the subject of an earnest and profound debate
across the country," and whether the "basic and consequential tradeoffs involved in such a
choice are ones that Congress would likely have intended for itself." 1/1/esf Virginia, 597 U.S.
at 732, 730; Biden v. Nebraska, 600 U.S. at 506. As addressed in this RTC in section
2.1.2.1.4, those factors are present for the Endangerment Finding.
EPA Summary of Comments
Commenters further asserted that while Massachusetts did not use the phrase "major
questions doctrine," one of the EPA's main arguments in that case was a major questions
argument-that air pollution should not be read to include GHGs because the statute is
insufficiently clear and GHG regulation would have vast economic and political
consequences. Commenters stated that Massachusetts considered the EPA's major
questions argument based on Brown & Williamson and rejected it because the statute was
clear and there was no comparable indication that Congress had sought to constrain
agency action. Commenters also said Massachusetts could not have explicitly applied the
major questions doctrine because the Supreme Court had not formally adopted it. But,
commenters argued, even if one reads the major questions doctrine analysis into
Massachusetts' holding and considers West Virginia and UARG, the case still supports
EPA's authority to regulate GHG emissions.
EPA Response
Massachusetts did not directly address the major questions doctrine. Rather, the Court
distinguished Massachusetts from Brown & Williamson on its facts and more particular
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rationales, as discussed above. See, e.g., Coalition for Responsible Regulation, Inc. v. EPA,
2012 U.S. App. LEXIS 25997, *52 (D.C. Cir. 2012) (Brown and Kavanaugh, dissenting)
("Although the Massachusetts Court distinguished Brown & Williamson, it did so only in the
context of tailpipe emissions."). Further, the EPA reads Massachusetts in light of what the
Court has said since then in cases like UARG and West Virginia, Nebraska, and Ala. Ass'n of
Realtors. For instance, while Massachusetts gave short shrift to legislative history
indicating that Congress had tried and failed to enact legislation specifically authorizing
regulation of GHGs, 549 U.S. at 530-31, the Court's major questions doctrine analysis in
West Virginia considered such failure to be relevant, 597 U.S. at 731. Massachusetts
considered Brown & Williamson distinguishable on the basis that FDA's interpretation there
would lead to a ban on tobacco products, whereas interpreting the CAA to encompass
GHGs would lead the EPA only to "regulate emissions." 549 U.S. at 531. But in West Virginia,
the Supreme Court observed that major questions cases "have arisen from all corners of
the administrative state." 597 U.S. at 721. The Court has refused to set arbitrary boundaries
on the doctrine based on the nature of the governmental action in question (such as
whether the action merely confers a benefit). Nebraska, 600 U.S. 477, 505-06.
Evolving judicial treatment since Massachusetts indicates that as a method for discerning
congressional intent, the major questions doctrine has a role beyond the specific confines
of Brown & Williamson. Analysis under the major questions doctrine may be appropriate in
extraordinary cases where there is doubt as to whether Congress intended to give the
agency the authority it asserted and where the agency may seek to assert power of great
economic and political significance. "Th[e] major questions canon reflects both
background separation of powers understandings and the commonsense interpretive
maxim that Congress does not usually 'hide elephants in mouseholes' when granting
authority to the President." Fed. Commc'ns Comm'n v. Consumers' Rsch., 606 U.S. 656,
706 (2025) (Kavanaugh, J., concurring) (quoting Whitman, 531 U. S. at 468). "The major
questions doctrine requires an agency to point to 'clear congressional authorization'when
it asserts an 'enormous and transformative expansion' of its 'regulatory authority' by
making a decision of'vast "economic and political significance.'" United States v. Navarro,
2024 U.S. App. LEXIS 7683, *8 (D.C. Cir. Apr. 1, 2024) (quoting UARG, 573 U.S. 302, 324,
(quoting FDA v. Brown & Williamson, 529 U.S. 120,160)). See also Save Jobs USA v. U.S.
Dep't of Homeland Sec., 111 F.4th 76, 80 (D.C. Cir. 2024) ("Like a dictionary, or expressio
unius, or the extraterritoriality canon, the major questions doctrine is a tool of statutory
interpretation.... [T]he function of the major questions doctrine is simple -to help courts
figure out what a statute means."). But see id. (decliningto overturn prior decision on basis
of "major questions doctrine" arguments, because statute's meaning had already been
discerned in prior case).
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The EPA concludes that the best interpretation of CAA section 202(a)(1) is that it does not
authorize GHG emissions regulation in response to global climate change concerns. We
clarify that "air pollution" as used in CAA section 202(a)(1) refers to phenomena that
adversely impact public health and welfare through local or regional exposure. Even if a
court were to disagree with our best reading of the statute, a clear statement is required for
the EPA to regulate GHGs due to global climate change undersection 202(a)(1) because
the major questions doctrine applies.
Further, the statute does not include a clear statement required under the major questions
doctrine that the EPA may regulate GHG emissions in response to global climate change
concerns. Under the major questions doctrine, even unambiguously broad discretion is not
enough to serve as a clear statement of authority to decide a major policy question. As an
illustration, a statutory general housekeeping provision that authorizes the Administrator to
issue "all necessary and appropriate regulations to carry out the purposes of this chapter"
is unambiguously broad. Yet it does not confer substantive authority for the agency to
implement novel interpretations to address major policy question by itself and it is not a
clear statement of authority to decide major questions in a way that the agency concludes
furthers the statute's purposes. Many major questions doctrine cases evaluate statutory
language that is unambiguously broad but nevertheless bound by the doctrine. In those
situations, applying the major questions doctrine serves to help avoid constitutional
concerns. See West Virginia, 597 U.S. at 737 (Gorsuch, J. concurring) ("The major questions
doctrine works in much the same way to protect the Constitution's separation of powers.");
id. at 766 (Kagan, J. dissenting) ("Congress does not usually grant agencies the authority to
decide significant issues on which they have no particular expertise. So when there is a
mismatch between the agency's usual portfolio and a given assertion of power, courts have
reason to question whether Congress intended a delegation to go so far. The majority today
... announces the arrival of the 'major questions doctrine,'which replaces normal text-in-
context statutory interpretation with some tougher-to-satisfy set of rules.").
In addition to Massachusetts not holding that CAA section 202(a)(1) is unambiguous, the
major questions doctrine does not hinge on statutory ambiguity. In certain "extraordinary
cases," the "history and breadth of the authority that the agency has asserted, and the
economic and political significance of that assertion, provide a reason to hesitate before
concluding that Congress meant to confer such authority." West Virginia, 597 U.S. at 721
(quoting Brown & Williamson, 529 U.S. at 159-60). Statutory ambiguity is not a prerequisite
to the doctrine's applicability as its role is to situate text in context to lead to the best
interpretation of the statute. See, e.g., Save Jobs USA, 111 F.4th at 80 ("[T]he function of the
major questions doctrine is simple - to help courts figure out what a statute means.").
Additionally, under Loper Bright, ambiguity is no longer the relevant question - the question
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is what is the best reading of the statute, guided by the major questions doctrine. See
Missouri v. Trump, 128 F.4th 979 (8th Cir. 2025) (court first engaged in statutory
interpretation to determine best reading then concluded even if there is plausible textual
basis, MQD applied and precluded government's interpretation); Mayfieldv. DOL, 117 F.4th
611 (5th Cir. 2024) (court first concluded MQD did not apply then determined DOL was
within its statutory authority in issuing minimum salary rule).
EPA Summary of Comments
Some commenters contended that West Virginia applied the same analytical framework
from Brown & Williamson and did not announce a new major questions doctrine out of
whole cloth. They also stated that UARG also recognized that the Court was merely
applying the longstanding Brown & Williamson standard, and that neither West Virginia nor
UARG provides new guidance on how to interpret and apply statutes warranting
reconsideration of the Endangerment Finding.
EPA Response
The EPA disagrees with the comments suggesting that West Virginia applied the same
analytical framework from Brown & Williamson and did not create a new major questions
doctrine. Loper Bright, in addition to West Virginia, indicate that courts are reviewing
agency interpretations of statutes differently than when the EPA issued the Endangerment
Finding in 2009. Biden v. Nebraska, West Virginia, UARG, and other recent Supreme Court
major questions doctrine cases have built on and further refined the doctrine since Brown
& Williamson, such that agencies have a fuller picture of what types of actions present
major questions. Additionally, West Virginia and UARG are of additional relevance
here because of the similarity of each case's facts to the issues in this rulemaking. It is
significant that the Supreme Court interpreted the CAA and largely rejected the EPA
assertions of authority that were in part premised on the Endangerment Finding, regardless
of whether these cases provide new guidance on statutory interpretation.
EPA Summary of Comments
Some commenters said that UARG and West Virginia lend Massachusetts's holding
additional support and do not undermine it. In both cases, commenters argue, the
Supreme Court could have held GHGs may not be regulated, but it did not so hold. Another
commenter characterized Massachusetts and UARG as effectively holding that regulating
GHG emissions under section 202 does not violate the major questions doctrine.
EPA Response
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The issues presented in UARG and West Virginia were focused on specific EPA rules, so the
EPA does not read any relevance into the Court not addressing whether the EPA
had authority to regulate GHGs in those contexts. In West Virginia, state petitioners raised
the following question: "In 42 U.S.C. § 7411 (d), an ancillary provision of the Clean Air Act,
did Congress constitutionally authorize the Environmental Protection Agency to issue
significant rules, including those capable of reshapingthe nation's electricity grids and
unilaterally decarbonizing virtually any sector of the economy-without any limits on what
the agency can require so long as it considers cost, nonair impacts, and energy
requirements?" West Virginia v. EPA, No. 20-1530, Petition for Writ of Certiorari, U.S.
Supreme Court (2021). One industry petitioner presented the following question: "Whether
42 U.S.C. § 7411 (d), which authorizes the EPA to impose standards "for any existing source"
based on limits "achievable through the application of the best system of emission
reduction" that has been "adequately demonstrated," grants the EPA authority not only to
impose standards based on technology and methods that can be applied at and achieved
by that existing source, but also allows the agency to develop industry-wide systems like
cap-and-trade regimes." West Virginia v. EPA, No. 20-1531, Petition for Writ of Certiorari,
U.S. Supreme Court (2021). Other state petitioners presented: "Can EPA promulgate
regulations for existing stationary sources that require States to apply binding nationwide
"performance standards" at a generation-sector-wide level, instead of at the individual
source level, and can those regulations deprive States of all implementation and decision
making power in creating their Section lll(d) plans?" West Virginia v. EPA, No. 20-1780,
Petition for Writ of Certiorari, U.S. Supreme Court (2021). Additional industry petitioners
presented: "1. Whether EPA may employ 42 U.S.C. § 7411 (d) to impose standards of
performance on existing stationary sources that are regulated under the "hazardous air
pollutants' program of 42 U.S.C. § 7412. 2. Whether 42 U.S.C. § 7411 (d) clearly authorizes
EPA to decide such matters of vast economic and political significance as whether and
how to restructure the nation's energy system." West Virginia v. EPA, No. 20-1778, Petition
for Writ of Certiorari (2021). The Court granted certiorari on all of the above except for the
question of whether the EPA may employ section 111 (d) to impose regulations on sources
regulated under the hazardous air pollutants program.
In UARG, the questions presented to the Court were:
After this Court decided Massachusetts v. EPA, 549 U.S. 497 (2007), the
Environmental Protection Agency (EPA) found that its promulgation of motor
vehicle greenhouse gas (GHG) emission standards under Title II of the Clean
Air Act (CAA), 42 U.S.C. § 7521 (a)(1), compelled regulation of carbon dioxide
and other GHGs under the CAA's Title I prevention of significant deterioration
(PSD) and Title V stationary-source permitting programs. Even though EPA
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determined that including GHGs in these programs would vastly expand the
programs contrary to Congress's intent, EPA adopted rules adding GHGs to
the pollutants covered. The [D.C. Cir.] panel below held the CAA and
Massachusetts compelled inclusion of GHGs and, based on that holding,
dismissed all petitions to review the GHG permitting program rules on
standing grounds. The questions presented are:
1. Whether Massachusetts compelled EPA to include GHGs in the PSD and
Title V programs when inclusion of GHGs would (i) transform the size and
scope of these programs into something that EPA found would be
"unrecognizable to . . . Congress," Petition Appendix 345a, 380a, and (ii)
expand the PSD program to cover a substance that does not deteriorate the
quality of the air that people breathe.
2. Whether dismissal of the petitions to review EPA's GHG permit-program
rules was inconsistent with this Court's standing jurisprudence where the
panel premised its holdingthat standingwas absent on its merits holding that
GHGs are regulated "pursuant to automatic operation of the CAA." Id. at 96a."
Utility Air Regulatory Group v. U.S. Environmental Protection Agency, No. 12-1146, Petition
for Writ of Certiorari, U.S. Supreme Court (2013).
The Court, through a docket entry, granted certiorari "limited to the following question:
Whether the EPA permissibly determined that its regulation of greenhouse gas emissions
from new motor vehicles triggered permitting requirements under the Clean Air Act for
stationary sources that emit greenhouse gases."
As the questions presented and issues granted for certiorari demonstrate, the Court was
not addressing the EPA's authority to regulate GHGs under 202(a) more generally in either
UARG or West Virginia.
EPA Summary of Comments
Some commenters stated that even if the Court overruled Massachusetts and applied the
major questions doctrine, the history and context of the CAA generally and 202 specifically
indicate Congress intended the EPA to regulate GHGs. This issue, they argue, bears no
resemblance to UARG, where the Court found that regulating GHGs under PSD CAA
program would require permits forthe construction and modification of tens of thousands,
and the operation of millions, of small sources nationwide.
EPA Response
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As discussed in the final action preamble and elsewhere in this document, the EPA
disagrees with the commenters' statement that Congress authorized the Agency to
regulate GHG emissions from motorvehicles under CAA section 202(a)(1) and with its
characterization of UARG.
EPA Summary of Comments
Commenters also stated that cases after Massachusetts have affirmed the EPA's authority
to regulate GHGs. For example, commenters argued that the holding in American Electric
Power v. Connecticut, 564 U.S. 410 (2011) is decisive and reaffirms that the CAA provides
the EPA authority to address global climate change, including by promulgating
implementing standards. They contend that other decisions have upheld GHG mobile
source regulations, like Coalition for Responsible Regulation v. EPA, 684 F.3d 102 (D.C. Cir.
2012). They stated that the Supreme Court in UARG affirmed the part of the DC Circuit's
judgment that the Endangerment Finding and Tailpipe Rule are neither arbitrary nor
capricious, and that Coalition expressly applied Massachusetts in upholding the
Endangerment Finding.
EPA Response
The EPA disagrees with the commenters' assertion that American Electric Power (AEP)
affirmed Massachusetts and the EPA's authority to regulate GHG emissions to address
global climate change. The questions before the court in AEP were:
1. Whether States and private parties have standing to seek judicially
fashioned emissions caps on five utilities for their alleged contribution to
harms claimed to arise from global climate change caused by more than a
century of emissions by billions of independent sources.
2. Whether a cause of action to cap carbon dioxide emissions can be implied
under federal common law where no statute creates such a cause of action,
and the Clean Air Act speaks directly to the same subject matter and assigns
federal responsibility for regulating such emissions to the Environmental
Protection Agency.
3. Whether claims seeking to cap defendants' carbon dioxide emissions at
"reasonable" levels, based on a court's weighing of the potential risks of
climate change against the socioeconomic utility of defendants' conduct,
would be governed by "judicially discoverable and manageable standards" or
could be resolved without "initial policy determination[s] of a kind clearly for
nonjudicial discretion." Baker v. Carr, 369 U.S. 186, 217 (1962)."
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American Electric Power v. Connecticut, No. 10-174, Petition for Writ of Certiorari,
U.S. Supreme Court (2010).
The court granted certiorari on all three questions, none of which included whether the EPA
has authority to regulate GHGs from motor vehicle emissions in response to global climate
change concerns. The question of authority was neither before the Court nor decided in
AEP.
First, the Court in AEP noted the limited scope of Massachusetts' holding: "Massachusetts
held that the Environmental Protection Agency (EPA) had misread the Clean Air Act when it
denied a rulemaking petition seeking controls on greenhouse gas emissions from new
motor vehicles. Greenhouse gases, we determined, qualify as 'air pollutants'within the
meaning of the governing Clean Air Act provision [42 U.S.C. § 7602(g)]." Am. Elec. Power
Co., 564 U.S. at 416 (internal citations and quotes omitted).
Second, the Court in its subsequent West Virginia decision rejected the commenter's
argument, expressly distinguishing/AEP. 597 U.S. at 730 ("The dissent also cites our
decision in American Elec. Power Co. v. Connecticut, 564 U.S. 410 (2011). The question
there, however, was whether Congress wanted district court judges to decide, under
unwritten federal nuisance law, whether and how to regulate carbon dioxide emissions
from power plants. We answered no, given the existence of Section 111 (d). But we said
nothing about the ways in which Congress intended the EPA to exercise its power under
that provision.") (internal citations and quotes omitted). Further, although the D.C. Circuit
relied heavily on the commenters' reading of AEP in American Lung, the Supreme Court
largely reversed American Lung in West Virginia. See West Virginia, 597 U.S. 697, 731 n.4;
id. at 745 (Gorsuch, J. concurring) (favorably citing Judge Walker's dissent in American
Lung).
Third, the Court in AEP described its holding in Massachusetts in general terms. The Court
stated that the CAA "authorizes federal regulation of emissions of carbon dioxide and other
greenhouses gases." 564 U.S. at 416. The EPA does not dispute that C02 and the other
individual GHGs (HFCs, methane, etc.) are air pollutants that can be subject to regulation
as provided in the CAA. What we dispute is that CAA section 202(a)(1) authorizes us to
regulate GHGs qua GHGs in response to global climate change concerns. In other words,
we have authority under the CAA to regulate vehicle emissions of these gases to the extent
they endanger public health or welfare through local or regional exposure. We also have
authority to regulate emissions of these gases from stationary sources where the same is
true {i.e., C02 in a dry ice factory where there is a risk of asphyxiation; elsewhere the CAA
requires us to regulate HFCs).
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The Court very carefully tailored its discussion in/AEP-GHGs are "within EPA's regulatory
ken" because they are "air pollutants." The Court cited to the Act-wide definition of "air
pollutant" in CAA 302(g), not the authority to set motor vehicle emission standards in CAA
section 202(a)(1). The Court noted that the EPA "had authority to set greenhouse gas
emission standards," but that general statement is not inconsistent with the EPA's more
specific view that CAA 202(a)(1) does not authorize the EPA to regulate GHG emissions
from motor vehicles in response to global climate change concerns. The critical point,
according to the Court, was that Congress vested the EPA with the decision "whether and
how" to regulate carbon dioxide emissions from power plants and the delegation displaces
federal common law. AEP, 564 U.S. at 426 (2011).
Finally, commenters rely on language in AEP that is dicta that has no bearing on the issues
in this final action. See Turkiye Halk Bankasi A.S. v. United States, 598 U.S. 264, 278 (2023)
("This Court has often admonished that general language in judicial opinions should be
read as referring in context to circumstances similar to the circumstances then before the
Court and not referring to quite different circumstances that the Court was not then
considering.") (internal citations omitted); Reiterv. Sonotone Corp., 442 U.S. 330, 341
(1979) ("the language of an opinion is not always to be parsed as though we were dealing
with the language of a statute."). AEP addressed entirely different questions about the
preemption of federal common law and in a different statutory context, under CAA section
111 rather than CAA section 202(a)(1).
The EPA also disagrees with the assertion that Coalition precludes the EPA's application of
the major questions doctrine to the Endangerment Finding. State and industry petitioners
challenged several aspects of the Endangerment Finding, including the EPA's interpretation
of CAA 202(a)(1), the adequacy of the scientific record supporting the Endangerment
Finding, the EPA's decision notto quantify the risk of endangerment to public health or
welfare created by climate change, the EPA's choice to define the air pollutant at issue as
an aggregate of six GHGs, the EPA's failure to consult its Science Advisory Board before
issuing the Endangerment Finding, and the EPA's denial of all petitions for reconsideration
of the Endangerment Finding. Coalition, 684 F.3d 102,117 (D.C. Cir. 2012). The challengers
took issue with the EPA's interpretation of 202(a)(1) at the time as a science-based
judgment devoid of policy concerns and regulatory consequences, specifically that it was
arbitrary and capricious for the EPA to not consider the benefits of activities that require
GHG emissions, the effectiveness of emission regulation triggered by the Endangerment
Finding, and the potential for societal adaptation to or mitigation of climate change. Id.
Notably, petitioners did not raise whether the Endangerment Finding ran afoul of the major
questions doctrine. As such, Coalition did not address whether the major questions
doctrine applies to the Endangerment Finding. The court acknowledged that "nothing in the
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CAA requires regulation of a substance simply because it qualifies as an 'air pollutant'
under this broad definition." Id. at 135. By contrast, Coalition did not hold that CAA section
202(a)(1) includes a clear statement of authority to regulate GHGs in response to global
climate change concerns, which is what is required when the major questions doctrine
applies. West Virginia, 597 U.S. 697, 732.
The EPA also disagrees with commenters' assertion that UARG generally affirmed
Coalition. The Supreme Court in UARG reversed Coalition in part and affirmed only one part
of that multi-faceted option. Given the nature of its grant of certiorari, the Court in UARG
was reviewing only a portion of the issues addressed in Coalition. In UARG, the Supreme
Court applied the major questions doctrine to reject expanding the number of stationary
sources subject to the CAA's PSD and Title V permitting requirements based on their GHG
emissions. 573 U.S. at 310-13. The Court held that the EPA "exceeded its statutory authority
when it interpreted the Clean Air Act to require PSD and Title V permitting for stationary
sources based on their greenhouse gas emissions" and "may not treat greenhouse gases
as a pollutant" for purposes of defining a major source or modification in the PSD and Title
V contexts. Id. at 333. In reaching this conclusion, the Court found that our interpretation of
the statute and related "tailoring rule" that exempted many sources to address workability
concerns was "unreasonable because it would bring about an enormous and
transformative expansion in EPA's regulatory authority without clear congressional
authorization." Id. at 324. The Court concluded that the EPA permissibly determined that a
source already subject to the PSD program because of its emission of conventional
pollutants may be required to limit its GHG emissions by employing the best available
control technology (BACT) for GHGs. Id. at 331. The Court focused on "the more specific
phrasing of the BACT provision" suggesting that Congress had already made the necessary
judgment and concluded "nothing in the statute categorically prohibits EPA from
interpreting the BACT provision" to apply to sources already subject to the PSD program. Id.
at 332. The narrow holding that sources that were already subject to the PSD program
because of conventional pollution emissions may also be required to limit GHG emissions
(based on this pollutant being subject to regulation under another part of the CAA) should
not be interpreted as a broad affirmation of Coalition, which addressed more issues than
the Court did in UARG. The fact of regulation of GHGs under 202 was taken as a given in
this part of the UARG opinion, without any analysis of whether the EPA's reading of section
202 was the best. Holdings in subsequent Supreme Court cases indicate that Coalition
misread the statute in several other respects that the Supreme Court did not consider in
UARG.
Further, UARG generally undermined the reasoning in other parts of Coalition that were not
directly before the Court in UARG. Applying its understanding of Massachusetts, the D.C.
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Circuit in Coalition held that reading "air pollutant" as "any regulated air pollutant" was
"compelled by the statute" and rejected petitioners' arguments that the PSD provisions
should be read in context as focusing on localized "air pollution" problems. Id. at 134,138.
Both times the D.C. Circuit touched on these issues, in Coalition and American Lung, the
Supreme Court reversed major parts of the D.C. Circuit's analysis.
EPA Summary of Comments
Commenters said that the EPA's statement that response to climate change is beyond the
purview of the Act is further belied by Section 109(b)'s requirement that the EPA adopt
secondary NAAQS to protect public welfare from adverse effects. Commenters state that
public welfare includes adverse effects on climate and notes that the renewable fuel
provision of CAA section 211 (o) is likewise premised on achieving positive GHG emission
balance for vehicular fuel.
EPA Response
The EPA disagrees that reference to the term "public welfare" in CAA section 109(b)
includes the global climate change theory relied on by the Endangerment Finding. RTC
section 2.1.1.1 discusses our analysis the meaning of "welfare" as defined in CAA section
302(h) and why it is consistent with the EPA's best reading of CAA section 202(a)(1). This
approach is consistent with our general obligation to distinguish between the "Act-wide
definition" of air pollutant and the application of that definition to the Act's regulatory
provisions. See UARG v. EPA, 573 U.S. 302, 320 (2014).
The EPA disagrees with the commenters' characterization of the RFS program, which is
evidence for the view that when Congress wants to address GHGs, it does so expressly and
in a different manner. Further, CAA section 211 (o)(12) makes clear that the RFS program
cannot be used to infer authorities elsewhere in the CAA. See RTC Section 2.1.1.1.1 for
additional discussion.
Holdings in subsequent Supreme Court cases indicate and which the Court disagreed with
that Coalition misread the statute in several other respects that the Supreme Court did not
consider in UARG points.
2.1.2.1.2 The Endangerment Finding was an unheralded use of agency
power
EPA Summary of Comments
The EPA received comments contending that the major questions doctrine reinforces that
the EPA acted outside its statutory authority in issuing the Endangerment Finding.
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Commenters stated that Congress enacted the CAAto address local air pollutants like
those that cause smog, and for decades after the CAA's enactment, the EPA
never attempted to regulate GHG emissions from vehicles. Commenters stated that the
EPA reversed course in 200 and in doing so, it attempted to resolve questions of immense
economic and practical significance - which remain the subject of a fierce, ongoing
political debate-without clear authorization from Congress.
Commenters further said that when the EPA published notice of its Endangerment Finding
in May 2009, the Obama administration's press release announced "a new national policy
aimed at both increasingfuel economy and reducing greenhouse gas pollution for all new
cars and trucks sold in the United States." Press Release, The White House Off. of the Press
Sec'y, President Obama Announces National Fuel Efficiency Policy, May 19, 2009,
https://tinyurl.com/y6sprxjn. Commenters stated that the White House made sure to
emphasize that this was "the first time in history" that the federal government had
regulated GHGs like carbon dioxide and that the Obama administration was right to
highlight the unprecedented nature of the Endangerment Finding. For decades,
commenters stated, Congress had avoided thorny question of GHG regulation.
Commenters stated that anthropogenic global warming had been a "prominent national
and international issue" since the 1980s, when "scientific discussions about the possibility
of global climate change led to growing public concern both in the U.S. and abroad,"
Fabricant Memo, supra, at 5, yet "[fjrom the late 1970s" through 2009, "Congress
repeatedly considered climate change legislation, and consistently refused to authorize
regulatory controls on greenhouse gas emissions." Jonathan H. Adler, Warming Up to
Climate Change Litigation, 93 Va. L. Rev. In Brief 63, 70 (2007) (emphasis added).
Commenters stated that the Supreme Court recognized that the Endangerment Finding
and related regulations resulted in "the single largest expansion in the scope of the [CAA] in
its history." UARG, 573 U.S. at 310. Commenters argued that this was not an unintended
consequence - the EPA admitted that regulating GHGs "would constitute an
'unprecedented expansion of EPA authority that would have a profound effect on virtually
every sector of the economy and touch every household in the land.'" Id. at 310-11 (quoting
73 FR 44354, 44355 (proposed July 30, 2008)). Regulations issued pursuant to the
Endangerment Finding have borne out the EPA's prediction, commenters contend.
EPA Response
The EPA agrees that the Endangerment Finding was a novel and unheralded use of its
authority under CAA section 202(a)(1) for the reasons discussed in the final action
preamble and elsewhere in this document.
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EPA Summary of Comments
Some commenters said that regulating GHGs under CAA section 202(a)(1) is not
unheralded. They argued that the EPA has consistently regulated GHGs for going on two
decades under CAA section 202(a) and that the EPA mistakenly focuses on whether the
finding was unheralded or novel in 2009 and not today. Commenters state that all three
branches of government recognized the EPA's authority to regulate GHGs before the
Endangerment Finding. They state that the Supreme Court explicitly recognized the EPA's
authority and obligation to regulate GHGs under CAA section 202(a) in Massachusetts if
the science showed they contribute to climate change, Congress understood and expected
that the CAA would authorize the EPA to regulate climate-altering emissions from its
enactment, and that the plain text and legislative history both demonstrate Congress
intended to empower the EPA to mitigate harms caused by changes to the climate.
Commenters state that the EPA's recognition of its authority to regulate GHGs under the
CAA likewise long predates the 2009 Endangerment Finding.
EPA Response
The Endangerment Finding was an unprecedented and unheralded use of CAA
section 202(a)(1) as the regulatory history from the passage of CAA section 202(a)(1) in
1965 to today demonstrates in two significant ways. First, during the first 40 years of this
provision's history, encompassing dozens of rulemakings and many different classes and
categories of motor vehicles, the EPA strictly limited the scope of its regulations under CAA
section 202(a)(1) to the air pollutants Congress had identified in more specific provisions in
CAA section 202. Second, prior to 2009, the EPA did not use its CAA section 202(a)(1)
authority to launch an entirely new arena of regulation which Congress had never
authorized or instructed the EPA to enter, whether in CAA section 202 specifically or in any
other provision or program regulating source emissions. A review of the EPA's motor
vehicle regulatory history reveals that the Endangerment Finding was an unheralded use
of section 202(a)(1). The EPA's subsequent 15 years of regulating GHGs is an aberration
compared to the previous 40 years and can't paper over an otherwise novel use of
authority.
The following examples of regulations the EPA issued between 1965 and the Endangerment
Finding in 2009 illustrates these points:
• 1980: The EPA regulated hydrocarbons, carbon monoxide, and nitrogen oxides
consistent with its "specific[]" authority in § 202(a)(3). The Control of Air Pollution
From New Motor Vehicles and Motor Vehicle Engines; Gaseous Emission
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Regulations for 1984 and Later Model Year Light-Duty Trucks, 45 FR 63734, 63735
(Sept. 25,1980).
• 1983: The EPA promulgated a final action consistent with its authority in § 206(f)(1)
amending hydrocarbon, carbon monoxide, and nitrogen oxide emission standards.
Control of Air Pollution from New Motor Vehicles and New Motor Vehicle Engines;
Emission Standards for 1984 and Later Model Year Light-Duty Vehicles and Light-
Duty Trucks, 48 FR 48598, 48599 (Oct. 19,1983).
• 1984: The EPA delayed the effective date for particulate emission standards
consistent with specific provisions in CAA section 202. Standards for Emission of
Particulate Matter From Diesel-Powered Light-Duty Vehicles and Light-Duty Trucks
and Technical Amendment to Emission Regulations for Light-Duty Vehicles, Light-
Duty Trucks, and Heavy-Duty Engines, 49 FR 3010, 3015 (Jan. 24,1984).
• 1988: The EPA revisited particulate matter emission standards consistent with CAA
section 202(a)(3)(A)(iii). Control of Air Pollution From New Motor Vehicles and New
Motor Vehicle Engines; Revision of Particulate Emission Standards for Certain 1987
and Later Model Year Light-Duty Diesel Trucks, 53 FR 43870, 43871 (Oct. 31, 1988).
• 1994: The EPA issued a rule implementing Congress's direct command in § 202(a)(6)
to promulgate standards requiring light-duty vehicles to have onboard refueling
vapor recovery systems to limit vehicle refueling emissions—specifically
hydrocarbons. Control of Air Pollution From New Motor Vehicles and New Motor
Vehicle Engines; Refueling Emission Regulations for Light-Duty Vehicles and Light-
Duty Trucks, 59 FR 16262, 16263 (April 6, 1994). In the same action, consistent with
this direction the EPA also applied these same requirements to light-duty trucks. Id.
• 1994: The EPA "extend[ed] the coverage of the existing federal motor vehicle
emissions program to include natural gas and [liquified petroleum gas] vehicles."
Standards for Emissions From Natural Gas-Fueled, and Liquefied Petroleum Gas-
Fueled Motor Vehicles and Motor Vehicle Engines, and Certification Procedures for
Aftermarket Conversions, 59 FR 48472, 48473 (Sept. 21,1994). This included
hydrocarbons, carbon monoxide, nitrogen oxides, and particulate matter consistent
with specific provisions in CAA section 202. 59 FR 48474.
• 1995: The EPA targeted "[g]round-level ozone" by creating stricter, but voluntary,
emission standards for "volatile organic compounds... and nitrogen oxides" for
States in the "northeast region of the country." Final Rule on Ozone Transport
Commission; Low Emission Vehicle Program forthe Northeast Ozone Transport
Region, 60 FR 4712, 4714 (Jan. 24, 1995). The goal, the EPA said, was to combat the
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smog that "damages lungtissue, reduces lung function, and sensitizes the lungs to
other irritants." 60 FR 4712. Manufacturers could voluntarily opt into these stricter
voluntary standards. 60 FR 4714.
• 1995: Consistent with three specific CAA provisions the EPA modified emission
testing procedures for methanol-fueled vehicles. Control of Air Pollution From New
and In-Use Motor Vehicles and New and In-Use Motor Vehicle Engines; Technical
Amendments to the Test Procedures for Methanol-Fueled Motor Vehicles and Motor
Vehicle Engines and Petroleum-Fueled Motor Vehicles; final rule, 60 FR 34326 (June
30,1995). These testing procedures measured hydrocarbons, nitrogen oxides, and
carbon monoxide. Id.
• 1997: The EPA created a voluntary national low emission vehicle program for light-
duty vehicles aimed at reducing particulate matter, nitrogen oxides, carbon
monoxide, and volatile organic compounds. Control of Air Pollution From New
Motor Vehicles and New Motor Vehicle Engines: Voluntary Standards for Light-Duty
Vehicles, 62 FR 31192, 31195-96, 31198 (June 6, 1997).
• 1997: The EPA adopted emission standards consistent with § 202(a)(3) for
hydrocarbon and nitrogen oxides for"on-highway heavy-duty diesel-cycle engines ...
applying] to model year 2004 and later." Control of Emissions of Air Pollution From
Highway Heavy-Duty Engines, 62 FR 54694, 54699 (October 21, 1997).
• 2000: The EPA established "a single set of emission standards that apply regardless
of the fuel used and whether the vehicle is a car, a light truck, or a larger passenger
vehicle" aimed at reducing ground-level ozone and particulate matter pollution.
Control of Air Pollution From New Motor Vehicles: Tier2 Motor Vehicle Emissions
Standards and Gasoline Sulfur Control Requirements, 65 FR 6698, 6701 (Feb. 10,
2000). The rule limited ground-level ozone, id. at 6709; nitrogen oxide, volatile
organic compounds, and particulate matter, id. at 6716; and "benzene,
formaldehyde, acetaldehyde, 1,3-butadiene, and diesel particulate matter," id. at
6722.
• 2000: The EPA promulgated a rule consistent with § 202(a)(3) "reaffirming]... the
[hydrocarbon and nitrogen oxides] standard for diesel engines and [setting] new
emission standards for heavy-duty Otto-cycle engines and vehicles." Control of
Emissions of Air Pollution from 2004 and Later Model Year Heavy-Duty Highway
Engines and Vehicles; Revision of Light-Duty On Board Diagnostics Requirements,
65 F R 59896, 59898 (October 6, 2000).
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• 2001: The EPA established a program consistent with § 202(a)(3) to "regulate the
heavy-duty vehicle and its fuel as a single system." Control of Air Pollution from New
Motor Vehicles: Heavy-Duty Engine and Vehicle Standards and Highway Diesel Fuel
Sulfur Control Requirements, 66 FR 5002 (January 18, 2001).
• 2004: The EPA revised exhaust emission standards for highway motorcycles
consistent with its specific authority in § 202(a)(3)(E)—aimed at decreasing
hydrocarbon, nitrogen oxides, and particulate matter emissions. Control of
Emissions From Highway Motorcycles, 69 F R 2398, 2403 (Jan. 15, 2004).
• 2007: The EPA set standards consistent with § 202(l)(2) to "reduce emissions of the
many airtoxics that are hydrocarbons, including benzene, 1,3-butadiene,
formaldehyde, acetaldehyde, acrolein, and naphthalene." Control of Hazardous Air
Pollutants From Mobile Sources, Control of Hazardous Air Pollutants From Mobile
Sources, 72 F R 8428, 8430 (Feb. 26, 2007).
Subsequent to the Endangerment Finding, the EPA issued light-duty GHG vehicle
standards in 2010, 2012, 2020, 2021, and 2024 and heavy-duty GHG vehicle standards
in 2011,2016, and 2024.
In the EPA's last analysis before issuing the Endangerment Finding, the Administrator raised
several concerns about regulating GHG emissions from motor vehicles under 202(a), both
in terms of consequences for future regulations that the agency would issue and for the
effect on jobs and the U.S. economy. 73 FR 44354, 44355 (July 30, 2008).
As the regulatory history demonstrates, the EPA's use of section 202(a)(1) in 2009 was the
first time the EPA launched a new area of regulation outside the scope of Congress'
direction in other specific provisions in CAA section 202, regulating GHG emissions in
response to global climate change concerns. The history of CAA section 202 is one of
Congress adding more specific authorities and obligations and the EPA implementing
those authorities and obligations, not one of the EPA racing out ahead with pathbreaking
applications of section 202(a)(1). Before 2009, the EPA generally regulated within the scope
of pollutants as intended by Congress, as the regulatory history shows.
EPA Summary of Comments
Some commenters said that the fact that the EPA has consistently claimed and exercised
the authority in question for more than 15 years, without rebuke from Congress or the
courts, makes this situation unlike cases in which the Supreme Court has applied the
major questions doctrine.
EPA Response
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The EPA disagrees with the commenters' assertion that the courts, Congress, and other
administrations have presumed the EPA has the authority to regulate GHGs from new
motor vehicles, as addressed in the final action preamble and elsewhere in this document.
First, the commenters' argument is irrelevant because MQD asks whether the assertion -
here, in 2009-was unheralded. West Virginia demonstrates that the passage of time does
not make an MQD violation less concerning. The CPP was issued in 2015 and it didn't come
before the Court for its review until 2022, when the Court concluded the CPP violated the
major questions doctrine in West Virginia. Second, the assertion is inaccurate because the
Endangerment Finding has been controversial from when it was issued until now, including
in the direct CAA section 202(a)(1) regulatory context and in virtually all attempts to expand
the regulatory implications of the Endangerment Findingto othertypes of emission
sources. When Congress intended the EPA to regulate fuel, it provided express and detailed
authority to do so, such as through the Renewable Fuel Standards (RFS) program.
EPA Summary of Comments
Commenters also said the Endangerment Finding did not substantially restructure an
entire market nor did it purport to fill statutory gaps under the guise of asserting regulatory
jurisdiction over an entire industry for the first time in its history, so it did not decide a major
question.
EPA Response
The EPA disagrees that the Endangerment Finding and vehicle rules are dissimilar from the
generation-shifting at issue in West Virginia. As addressed in the final action and this RTC,
the regulatory history demonstrates the EPA's regulations resulted in an increasing trend
towards EV production, affecting a significant sector of the American economy -
transportation. The regulations encouraged the transition from one type of fuel,
gasoline/diesel, to another, electricity.
EPA Summary of Comments
Commenters argued that the Endangerment Finding is about pollution control and
regulation and hardly compares in impact to that of the generation-shifting of the entire
American energy market at issue in West Virginia. Commenters state that emission
standards do not effectively overhaul the marketplace or eliminate an energy source as in
West Virginia and if they did, the Court in Massachusetts would have agreed with the EPA's
reliance on Brown & Williamson.
EPA Response
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The EPA disagrees with the commenters' suggestion that if GHG emission standards
violated the major questions doctrine, the Court would have agreed with the agency's
invocation of Brown & Williamson in Massachusetts for the reasons articulated in section
2.1.2.1.1 of this RTC.
2.1.2.1.3 The Endangerment Finding was a transformative expansion in
agency power
EPA Summary of Comments
Commenters stated that the Endangerment Finding transformed the EPA's authority: the
2009 Endangerment Finding triggering authority to promulgate GHG vehicle standards
under CAA section 202(a) has a far greater effect than just on new motor vehicles.
Commenters argued that the Endangerment Finding launched the EPA into becoming the
GHG regulator for the nation and served as a primary justification for regulating GHGs
across the CAA, including for the Obama administration's CPP that was struck down by the
Supreme Court in West Virginia. Commenters argue that if the major questions doctrine
was the basis for shooting down that rule, it is difficult to understand how the authority to
regulate GHGs under CAA section 202(a) and the Endangerment Findingthat was a
predicate for the CPP and other rules would not necessarily need to be shot down on major
questions grounds as well.
Commenters further argued that notwithstanding the CAA, the 2009 Endangerment Finding
invented a regulatory regime affecting virtually every aspect of the American economy,
from the cars people drive to the electricity that powers their homes and businesses.
Commenters argue that this is the kind of transformative assertion of power that the
Supreme Court has said requires a clear statement from Congress. E.g., Biden v. Nebraska,
600 U.S. at 514 (Barrett, J., concurring) ("This expectation of clarity is rooted in the basic
premise that Congress normally intends to make major policy decisions itself, not leave
those decisions to agencies."). Yet, commenters argue, the EPA based its action on Section
202(a)'s vague and general authority to "prescribe ... standards" for vehicle emissions.
Commenters stated that such "modest words" and "subtle devices" are not the clear and
explicit authorization required by the doctrine, and argued that an agency cannot use a
long-extant, ancillary provision of a statute to enact a fundamental reordering of the
national economy. West Virginia, 597 U.S. at 747 (Gorsuch, J., concurring) ("[A]n agency's
attempt to deploy an old statute focused on one problem to solve a new and different
problem may also be a warning sign that it is acting without clear congressional
authority.").
EPA Response
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The EPA agrees that the Endangerment Finding was a transformative expansion of the
Agency's authority under CAA section 202(a)(1) for the reasons discussed in the final action
preamble and this document.
EPA Summary of Comments
Some commenters said that regulating GHGs does not transform the EPA's authority under
CAA section 202(a)(1), arguing that GHGs are not inherently different than other air
pollutants that the EPA sets vehicle emission standards for.
EPA Response
The Endangerment Finding was an unprecedented and transformational assertion of the
EPA's authority under CAA section 202(a)(1). It was the first time in history that the federal
government had taken the first critical step to regulate GHG emissions from motor vehicles
under section 202(a)(1). As noted in the final action in section IV.B. 1, that history is telling
because section 202(a)(1) has existed in substantially similar form since 1967, yet the EPA
never regulated in this manner despite having issued many prior rules governing vehicle
and engine emissions. The theory of regulation in the Endangerment Finding is different
than other actions issued under section 202(a)(1). The theory of endangerment and
causation for GHGs was fundamentally different because it required extrapolating to a
global scale, finding phenomena attributed to the increased GHG concentrations such as
increased temperature and sea level rise, then findingthat those phenomena, and not the
gases themselves, eventually trickle down into adverse impacts on health or welfare. See
73 FR 44354, 44427 (July 30, 2008) ("Current and projected levels of ambient
concentrations of the six GHGs are not expected to cause any direct adverse health
effects, such as respiratory or toxic effects, which would occur as a result of the elevated
GHG concentrations themselves rather than through the effects of climate change.
However, there are indirect human health risks (e.g., heat-related mortality, exacerbated air
quality, extreme events) and benefits (e.g., less cold-related mortality) that occur due to
climate change." See also Coalition for Responsible Regulation, Inc. v. EPA, 2012 U.S. App.
LEXIS 25997, *41 -42 (D.C. Cir. 2012) (Brown, dissenting from denial of rehearing en banc)
("In order to reasonably anticipate that a pollutant will contribute to air pollution that
endangers public health or welfare, the Agency would have to conclude that pollution
created by C02 or another GHG is a reasonably direct cause of the damage to public health
and welfare. To find that C02 may ultimately endanger public health and welfare because
sea levels will rise tells us nothing about whether C02 concentrations in the ambient air
directly harm public health and welfare.").
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As discussed in RTC section 2.1.2.1.2, before 2009, the EPA never used CAA
section 202(a)(1) to launch a new area of regulation outside the scope of Congress'
direction identified in specific CAA section 202 provisions by regulating GHG emissions in
response to global climate change concerns. As such, it is like other statutory provisions
that courts have considered to be a highly unlikely mechanism through which Congress
would delegate a decision of economic and political significance. See West Virginia, 597
U.S. at 724-25. It is immaterial that the vehicles may already be subject to other emissions
standards; the agency may not impose regulatory burdens that it has no statutory authority
for.
EPA Summary of Comments
Commenters also argued that vehicle GHG standards are not based in a rarely used subtle
device, nor does it depend on a strained understanding of the text, but that regulating
GHGs from vehicles is squarely within the EPA's expertise. These commenters argued that
there is nothing unusual about the EPA issuing consequential regulations under section
202(a), nor does the nature of the authority change when applied to GHGs. Regulating
GHGs does not increase the number or types of sources subject to Section 202(a)
standards, they argue, but instead, it simply subjects sources that already emit multiple
pollutants regulated under section 202(a) to an additional standard.
EPA Response
The EPA disagrees with the commenters who argued that regulating GHGs under section
202(a) is not a rarely used subtle device nor is it based on a strained understanding of the
text. The EPA further disagrees that the EPA has special expertise in regulating GHGs from
new motor vehicles, particularly when it issued the Endangerment Finding in 2009. The
statutory history shows the scope of pollutants Congress directed the EPA to regulate
under section 202(a)(1), and the regulatory history shows the EPA staying within the scope
of those pollutants until its novel and transformative approach in the 2009 Endangerment
Findingto regulate GHG emissions from motor vehicles in response to global climate
change concerns. Textual plausibility is insufficient under the major questions doctrine;
clear congressional authorization is needed. As to agency expertise in regulating GHG
emissions from motor vehicles, the EPA did not have extensive climate science expertise in
2009 in regulating GHG emissions from new motor vehicles. The EPA has significant
experience in regulating vehicle and engine emissions, but specific to regulating
conventional air pollutants that cause harm through local or regional exposure, not in
response to global phenomena.
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Everything the EPA does with SIPs, criteria pollutants, and HAPs is one set of expertise. The
EPA has developed legal and methodological frameworks that cut across these areas. GHG
regulation is an entirely different field, and the EPA has struggled to develop separate legal
and methodological frameworks that work. The Supreme Court has consistently pushed
back on our attempts to do so, and they've remained controversial. Nor has Congress
taken them up into the CAA, as they did with certain of our criteria and HAP decisions (e.g.,
CAA section 112 expressly incorporating our Benzene NESHAP methodology for risk
reviews). As noted in the 2008 ANPRM, "[t]he implications of a decision to regulate GHGs
under the [Clean Air] Act are so far-reaching that a number of other federal agencies have
offered critical comments and raised serious questions... Rather than attempt to forge a
consensus on matters of great complexity, controversy, and active legislative debate, the
Administrator has decided to publish the views of other agencies and to seek comment on
the full range of issues that they raise." 73 FR 44354, 44354 (July 30, 2008).
EPA Summary of Comments
Some commenters asserted that the argument for regulating GHGs as transformative
based on the EPA's considering increased electrification and adopting standards that
require manufacturers to switch from using internal combustion engines to electrified
technology only criticizes a particular type of GHG regulation and is therefore unresponsive
to the question at hand. Commenters stated that increased electrification clearly falls
within the statutory scope as a technology that prevents or controls vehicular pollution.
EPA Response
The EPA disagrees with the assertion that the Endangerment Finding was not a
transformative use of the Agency's authority, for the reasons addressed in the final action
preamble and elsewhere in this document. The EPA views the comment regarding
increased electrification as within the statutory scope as a technology that prevents or
controls vehicular pollution as out of scope for this rulemaking as it is about other
pollutants and not whether the EPA has statutory authority to regulate GHG emissions from
motor vehicles in response to global climate change concerns.
EPA Summary of Comments
Commenters further argued that there is no indication that Congress has considered and
rejected the EPA's authority to regulate GHGs under CAA section 202(a). Commenters
stated that statutory enactments such as the AIM Act do not indicate the agency lacks
authority to act under other earlier enacted statutory provisions. Further, commenters
contended, those enactments postdate the 2009 Endangerment Finding and therefore
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were not enacted against a regulatory backdrop of disclaimers of regulatory authority.
Commenters stated that neither the OBBBA nor recent CRA resolutions address the EPA's
authority to regulate GHGs under section 202(a), attempts to revoke the EPA's authority to
regulate GHGs under the CAA have consistently failed, and other statutory enactments
since 2007 confirm Congress's understanding that GHGs are pollutants under CAA section
202(a). Commenters stated that the AIM Act was Congress' solution to a specific air
pollution problem, the rapid rise of a specific pollutant, in specific circumstances and it
was legislating against the backdrop of existing CAA provisions; it is no basis to constrain
the broad authority Congress clearly delegated to the EPA under CAA section 202(a)(1).
Commenters state that with one exception, the OBBBA merely rescinded appropriations
from the IRA and did not explicitly modify underlying program authority delegated to the
EPA. Commenters stated that Congress's disapproval of the methane waste emissions
charge and the California waiver do not retroactively create a major question because they
do not pertain to the Endangerment Finding and don't indicate any Congressional intent
regardingthe Endangerment Finding.
EPA Response
As further discussed later in this response and in the final action in section IV.B. 1, the AIM
Act, OBBBA, and CRA resolutions demonstrate that when Congress has addressed
GHGs, it has chosen to do so through more targeted means than the claimed broad
authority under CAA section 202(a)(1) to "prescribe ... standards", suggesting section
202(a)(1) should not be read in a way that is contrary to how Congress has legislated when
addressing GHGs.
Additionally, these commenters misstate the major questions doctrine. MQD does not
create an expectation that Congress affirmatively enact legislation to constrain prior
unauthorized assertions of authority. Rather, when Congress has considered but not
adopted legislation authorizing GHG regulation in response to global climate change, and
Congress has made relevant policy decisions by authorizing an agency to address
specifically identified problems within express frameworks for regulation, such as in the
AIM Act discussed in the final action and below, the agency must act within the scope of its
prescribed statutory authority.
Indeed, the legislative history in Congress since 2009 reveals at least congressional
ambivalence toward addressing climate change, and, particularly in the 119th
congressional session, Congress has become explicitly hostile toward programs to reduce
GHGs, repealing even the incentive programs and other funding programs related to GHG
emissions or climate change that it previously supported. These enactments and their
legislative history, as well as the many failed bills that would have more aggressively
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regulated emissions of GHGs, indicate that Congress has continued to consider the
regulation of GHGs a politically and economically significant issue in which it must play the
decisive role.
As discussed in the preamble, Congress considered but failed to enact legislation between
2007 (when Massachusetts was decided) and late 2009 (when the Endangerment Finding
issued). In that time period, Congress considered legislation - supported by the President
and Administrator in office at the time of the Endangerment Finding-that would have
authorized or required the EPA to prescribe emissions regulations for GHGs. For example,
the Safe Climate Act of 2007 would have adopted findings and policies with respect to
limiting global temperature increase, required various forms of international cooperation,
and added a new title VII to the CAA instructing the EPA to achieve phased GHG emission
reduction targets and regulate GHG emissions under CAA section 202.11 Also duringthis
time period, in a hearing concerning climate change legislation, Rep. John Dingell, one of
the lead co-authors of the 1990 CAA Amendments, stated that Massachusetts' holding that
GHGs can be air pollutants was "not what was intended by the Congress and by those of
who [sic] wrote that legislation."12
Upon taking office, President Obama understood that Congress needed to legislate to
address climate change. In his first State of the Union address in 2009, he called on
Congress to enact comprehensive climate legislation.13 But Congress failed to enact that
legislation. See West Virginia v. EPA, 142 S. Ct. 2587, 2614:
At bottom, the Clean Power Plan essentially adopted a cap-and-trade scheme, or
set of state cap-and-trade schemes, for carbon. See 80 FR 64734 ("Emissions
trading is... an integral part of our BSER analysis."). Congress, however, has
consistently rejected proposals to amend the Clean Air Act to create such a
program. See, e.g., American Clean Energy and Security Act of 2009, H.R. 2454,
111 th Cong., 1 st Sess.; Clean Energy Jobs and American Power Act, S. 1733,111 th
11 H.R.1590 (110th Cong.). This bill was presented in the House and never received a vote.
12Hr'g before the Subcomm. on Energy & Air Quality, House Comm. on Energy & Commerce at 8 (110th
Cong.Apr.10, 2008), available at https://wvwv.congress.gov/110/chrg/CHRG-110hhrg51574/CHRG-
110hhrg51574.pdf.
13 See Darren Samuelsohn, Climate bill needed to 'save our plant,'says Obama, N.Y. Times (Feb. 25, 2009),
available at https://archive.nytimes.eom/www.nytimes.com/cwire/2009/02/25/25climatewire-emissions-bill-
needed-to-save-our-planet-oba-9849.html?pagewanted=all. See also Evan Lehmann & Nathanael Massey,
Obama Warns Congress to Act on Climate Change, or He Will, Scientific American (Feb.13, 2013),
https://www.scientificamerican.com/article/obama-warns-congress-to-act-on-climate-change-or-he-will/
('"But if Congress won't act soon to protect future generations, I will,' Obama said. 'I will direct my Cabinet to
come up with executive actions we can take, now and in the future, to reduce pollution, prepare our
communities for the consequences of climate change, and speed the transition to more sustainable sources
of energy.'").
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Cong., 1 st Sess. (2009). It has also declined to enact similar measures, such as a
carbon tax. See, e.g., Climate Protection Act of 2013, S. 332,113th Cong., 1 st Sess.;
Save our Climate Act of 2011, H.R. 3242, 112th Cong., 1st Sess.
Examples of climate legislation that have failed to pass in Congress illustrate what a clear
statement to unambiguously authorize the EPA to regulate GHGs could look like. For
example, the failed Clean Energy Jobs and American Power Act of 2010, Senate Bill 1733,
would have set up its own comprehensive regulatory scheme while section 128 of that bill
would have then prohibited the EPA from regulating GHG emissions as NAAQS or HAPs air
pollutants under the Act.14 Similarly, section 331 of the failed American Clean Energy and
Security Act of 2009, H.R. 2454, would have prohibited the EPA from listing GHGs as a
criteria air pollutant or as a hazardous air pollutant.15 These examples illustrate attempts at
creating a comprehensive regulatory scheme for GHGs and how Congress could have
specified how the EPA is and is not to go about regulating GHG emissions, but Congress
has so far failed to enact these or any similar legislation.
These failed attempts stand in contrast to Congress's successful enactment of programs to
address other global air pollutants, such as regulation of stratospheric ozone layer
depleting substances in Title VI of the CAA. Indeed, when Congress has addressed GHGs
individually or collectively, it has not granted the EPA broad regulatory authority
comparable to our authority to "prescribe ... standards" under CAA section 202(a). With
respect to HFCs, Congress enacted a comprehensive phaseout scheme in the 2020
American Innovation and Manufacturing (AIM) Act, which includes detailed instructions,
timelines, and requirements for implementation and allows some uses to continue under
certain conditions.16 As another example, under CAA section 211, Congress set out
detailed requirements for the EPA's renewable fuel standards (RFS) program.
Indicative of the continuing political and economic significance of whetherto regulate GHG
emissions, most recently, the current Congress has begun actively removing the EPA's and
other agencies' authority to address GHGs and climate change more generally. In the
OBBBA, enacted on July 4, 2025 (Public Law 119-21), Congress:
• Repealed the GHG reduction fund (section 60002)
• Rescinded fundingfor GHG corporate reporting (section 60010)
• Rescinded fundingfor GHG air pollution plans and implementation grants (section
60013)
14 See S. 1733,111th Cong., https://www.congress.gov/biU/111th-congress/senate-biU/1733.
15 See H. 2454,111th Cong., https://www.congress.gOv/biU/111th-congress/house-biU/2454.
16 Pub. L. 116-260, Div. S (codified at 42 U.S.C. § 7675 etseq.).
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• Rescinded funding for environmental and climate justice block grants (section
60016)
• Rescinded fundingfor environmental and climate data collection (section 60018)
• Repealed, limited, or reduced many other tax incentives for clean energy and lower-
or zero-emitting sources of generation (see, for example, sections 70503-70509,
terminating numerous energy efficiency and clean energy tax credits).17
In supporting the OBBBA's termination of section 60002, Senator Capito referred to the
need to rein in spending on climate change that had been authorized in the Inflation
Reduction Act but lacked adequate oversight, noting Congress's "deep concern with
reducing the deficit."18 And Representative Alford emphasized that cutting these programs
would "rescind[] billions in green new scam funding."19
Congress also has expressed its opposition to reducing GHG emissions by passing CRA
resolutions blocking California from implementing state-specific GHG regulations for its
motor vehicle fleet under EPA-granted waivers. On June 12, 2025, President Trump signed
into law three resolutions adopted by Congress under the CRA to void waivers we granted
under CAA section 209 that allowed California and participating States to enforce GHG
emission regulations for motor vehicles and engines, up to and including zero-emissions
standards that mandated a shift to electric vehicles.20
As President Trump stated in his signing statement on June 12, 2025:
As the Congress's joint resolutions make clear, California's attempts to impose an
electric vehicle mandate, regulate national fuel economy, and regulate greenhouse
gas emissions are not eligible for waivers of preemption under section 209 of the
Clean Air Act. This provision of the Clean Air Act authorizes the Environmental
Protection Agency (EPA) to grant waivers to California to address only compelling
and extraordinary localized issues. It can never again be misused to regulate
greenhouse gas emissions, which inherently do not have localized effects, much
less compelling and extraordinary local effects, or vehicle emissions across the
Nation.21
17 See https://wvwv.congress.gOv/biLL/119th-congress/house-biLL/1/text.See also
https://www.novoco.com/notes-from-novogradac/the-finaL-one-big-beautifuL-biLL-act-is-bad-news-for-soLar-
wind-home-energy-efficiency-other-cLean-energy-tax-credits.
18 See H.R. 1,171 Cong. Rec. S4080 (June 30, 2025).
19171 Cong. Reg. H3039 (JuLy 2, 2025).
20 H.R.J. Res. 87; H.R.J. Res. 88; H.R.J. Res. 89; see also Diamond Alt. Energy, LLC v. EPA, 606 U.S.100,107 n.1
(2025); Statement by the President (June 12, 2025), https://www.whitehouse.gov/briefings-
statements/2025/06/statement-by-the-president.
21 See https://www.whitehouse.gov/briefings-statements/2025/06/statement-by-the-president.
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Representative Balderson said in support of the resolutions disapproving the EPA waivers,
"overturning] this waiver, protects] the right of every American to choose the vehicle that
works best for them.... Yet, the Biden administration chose to team up with radical climate
activists to support the one-size-fits-all electric vehicle mandate that the market and the
American people have clearly rejected."22 Senator Capito explained that "over the past two
decades, California has used its waiver authority to push its extreme climate policies on
the rest of the country, which was never the intent of the Clean Air Act's decision to grant
the waiver. As the EPA recognized in 2008, the rationale for California's ability to
seek waivers does not extend to greenhouse gases, as these levels are not unique
to California but are global in nature."23
As a final example, on May 19, 2025, President Trump signed into law a resolution adopted
by Congress under the Congressional Review Act (CRA) to void our final rule implementing
the waste emission charge added to the CAA in 2021.24
This give-and-take is not new. The legislative record going back to at least the 1980s
reflects a longstanding dialogue within Congress concerning the appropriate approach to
GHG emissions. Where Congress amended the CAA in 1990, it took a nonregulatory and/or
information gathering approach. See, e.g., 42 U.S.C. § 7403(g)(1), 7671 a(e), and 7651 k note.
And Congress enacted several statutory provisions outside the CAA that mandate research
and inter-agency coordination. See, e.g., 15 U.S.C. § 2901 et seq.; 15 U.S.C. § 2901 note; 15
U.S.C. § 2921-2938; 7 U.S.C. § 6701 et seq.; 42 U.S.C. § 13381-13388. Congress also
considered and expressly rejected proposals authorizing the EPA to regulate GHGs under
the CAA. See S. Rep. No. 101-228, at 377 (1989), as reprinted in 1990 U.S.C. §C.A.N. 3385,
3760. It has been estimated that hundreds of proposed bills have been introduced in
Congress to regulate GHGs between 1990 and 2009.25
All of these legislative developments indicate that Congress never intended to give the EPA
carte blanche authority to regulate GHGs under CAA section 202(a)(1), and the regulation
of GHGs is an issue of political and economic significance in Congress.
2.1.2.1.4 The Endangerment Finding has vast economic and political
significance
EPA Summary of Comments
22171 Cong. Rec. H1748 (Apr.30, 2025).
23171 Cong. Rec. S3086(May21, 2025).
24 Pub. L. No. 119-2; see 90 FR 21225 (May 19, 2025).
25 Abigail R. Moncrieff, Reincarnating the "Major Questions" Exception to Chevron Deference As A Doctrine of
Noninterference (or Why Massachusetts v. EPA Got It Wrong), 60 ADMIN. L. REV. 593, 636-37 (2008).
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Some commenters argued that the Endangerment Finding has a tremendous economic
cost- perhaps the most significant price tag of any major questions case the Supreme
Court has considered. Commenters stated that the EPA and others estimate that the seven
GHG emission standard regulations it has promulgated based on the Endangerment
Finding have "an aggregate cost of more than $1 trillion." EPA Press Off.,; see also
James Broughel, The Behavioral Economics Battle Lurking in EPA's Endangerment Finding
Repeal, FORBES (Aug. 11, 2025, 8:49 a.m.), https://tinyurl.com/ywtt97xb. and that these
enormous costs are a strong indicator that the major-questions doctrine applies. See
Ala. Ass'n of Realtors v. HHS, 594 U.S. 758, 764 (2021) (citing program's billion[s]" in
"economic impact"); King, 576 U.S. at 485 (same).
Commenters further said that Congress refused to pass bills requiring GHG emission
reductions, and that this resistance cametoa head duringthe 1990 CAA amendments.
Duringthat session, commenters stated, Congress considered multiple such bills. See,
e.g., S. 1224,101 st Cong. (1989); H.R. 5966,101st Cong. (1990); Arnold W. Reitze, Jr., 4
Century of Air Pollution Control Law: What's Worked; What's Failed; What Might Work, 21
Env't L. 1549,1633 (1991) ("Global warming issues are largely ignored by the 1990
Amendments."). Commenters stated that Congress even "explicitly considered the
adoption of vehicle emission controls" after "[a] provision to require such controls was
approved by the Senate Committee on Environment and Public Works, but was stricken
before final passage of the bill due to heated opposition." Jonathan H. Adler, Warming Up to
Climate Change Litigation, 93 Va. L. Rev. In Brief 63, 70 (2007). Commenters stated that
Congress refused any action along these lines. Henry A. Waxman, supra, at 2018
(bemoaning that even after the 1990 CAA amendments the CAA's "mobile source
provisions" fail to address the "important" "problem of global warming"). Commenters
stated that indeed, not only did Congress refuse to give the EPA regulatory power over
GHGs like carbon dioxide, but when the Cannon Memo suggested the EPA had the power to
unilaterally regulate GHGs, Congress "responded with appropriations riders explicitly
barring the expenditure of any EPA funds on developing or implementing such rules." Adler,
at 70. Commenters stated that all this was for many years considered strong evidence that
Congress has not given the EPA the authority to do so under general CAA provisions. See
Arnold W. Reitze, Jr., Global Warming, 31 ENV'T L. REP. 10,253, 10,259 (2001) ("Reitze
2001").
Commenters stated that a last signal of a major question pertains to federalism: when a
rule upsets the proper balance between the States and the federal government, that is
another good indication that the agency has overreached, at least absent a go-ahead from
Congress. To be sure, commenters argued, interstate air pollution has long been a federal
concern, especially considering Congress's choice to delegate authority to the EPA in this
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space. See City of New York v. Chevron Corp., 993 F.3d 81, 91 (2d Cir. 2021), Am. Elec.
Power Co. v. Connecticut, 564 U.S. 410,429 (2011). But, commenters contended, the scale
of federal interference engendered by the Endangerment Finding specifically extends
this particular regulatory effort beyond a national problem. By tackling GHG emissions in
this manner, commenters argued, the EPA has purported to interfere with all manner of
micro-level, intrastate, localized activities-transportation, manufacturing, local land use,
and more.
Commenters also argued that the consequences of the EPA's claimed authority are
themselves reason to demand a showing of clear congressional authorization, but there is
another reason too: the evidence shows that regulating GHG emissions from new motor
vehicles will have minimal effects at most. See EPA, Revised 2023 and Later Model Year
Light Duty Vehicle GHG Emissions Standards: Regulatory Impact Analysis 5-6 (2023)
(showing projected net reductions in cumulative C02 emissions of 78 million metric tons
from 2023 to 2030); Hannah Ritchie & Max Roser, C02 Emissions (Jan. 2024),
https://ourworldindata.org/co2-emissions (showing China's annual carbon dioxide
emissions at 11,902 metric tons annually); cf. Massachusetts, 549 U.S. at 544-46 (Roberts,
J., dissenting) (noting causation and redressability problems with regulating vehicle GHG
emissions to address climate change concerns). Commenters argued that regulating GHG
emissions entails complex policy tradeoffs. It is not plausible that Congress "gave EPA the
authority" to adopt so burdensome a regulatory scheme in return for so little, on such
uncertain grounds. West Virginia, 597 U.S. at 735.
EPA Response
The EPA agrees with the commenters and asserts that the economic and policy
consequences of the Endangerment Finding, in addition to the history and breath of the
asserted authority, provide a reason to hesitate before concluding that Congress intended
the EPA to regulate GHG emissions from motor vehicles, as discussed in the final action
preamble and elsewhere in this document.
EPA Summary of Comments
Commenters argued that high economic and political significance and congressional
action or inaction are not the sole or determinative criteria for when MQD applies.
Commenters contended that an agency action may have large or even significant political
and economic consequences and would not trigger MQD when the action fits neatly within
the language of the statute and aligns with the agency's statutory role.
EPA Response
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The EPA agrees that economic and political consequences are not the determinative
factors for when the major questions doctrine applies based on Supreme Court precedent;
however, for the reasons discussed in the final action preamble and elsewhere in this
document, the doctrine applies here because of the nature of the authority asserted
combined with the economic and political consequences of that assertion.
EPA Summary of Comments
Other commenters argued that the economic and political significance of regulating GHGs
under CAA section 202(a) is not different in kind than that of regulating other pollutants.
Commenters argued that the EPA would need to show that every conceivable exercise of
CAA section 202(a) authority to regulate GHGs would have extreme political and economic
significance that are different in kind than issuing emissions standards for other pollutants
under section 202(a) because the EPA is proposing it has no authority whatsoever to
regulate GHGs under section 202(a).
EPA Response
The economic consequences of the Endangerment Finding, aggregated through
the multiple rules imposing GHG emission standards, is significant, as discussed in
sections 2.1.2.5 and 2.1.2.2.2. The EPA disagrees with the suggestion that the agency
would need to show every rule it could hypothetically issue under section 202(a)(1) to
regulate GHG emissions has economic and political significance that are different in kind
than other emissions standards. The political significance of regulating GHGs from motor
vehicles is evident, as global climate change and how to respond is the subject of earnest
and profound debate across the country, as discussed in sections 2.1.2.6 and 2.1.2.2.2.
The EPA disagrees with the assertion that GHGs are not different than other conventional
air pollutants as discussed elsewhere in this document.
2.1.2.1.5 Economic Consequences
EPA Summary of Comments
The EPA received comments stating that the Endangerment Finding resulted in significant
economic consequences. Commenters stated that when the EPA decided to make the
Endangerment Finding and regulate GHGs under Section 202(a)(1), it claimed sweeping
authority with significant consequences. Cf. 2025 Regulatory Impact Analysis 33
(recognizing that cars and trucks are an $800 billion industry that "delivers] freedom,
mobility, and reliability" as an integral part of American society). Commenters further
stated that when the EPA initially established vehicle emissions standards for GHGs
following the Endangerment Finding, it identified $51.62 billion in anticipated manufacturer
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costs over the succeeding five years. Env'tl Prot. Agency, Final Regulatory Impact Analysis:
Rulemaking to Establish Light-Duty Vehicle Greenhouse Gas Emission Standards and
Corporate Average Fuel Economy Standards 6-12 (Apr.1, 2010) (identifying anticipated
manufacturer costs of $4.94 billion in 2012, $7.96 billion in 2013, $10.34 billion in 2014,
$12.74 billion in 2015, and $15.64 billion in 2016) (hereinafter "2010 Regulatory Impact
Analysis"). Commenters stated that these costs flow to the consumer; researchers
estimate that federal safety and emissions regulations account for 25% of the price of
vehicles. See Kyle Conrad et al., The Benefits and Costs of Automotive Regulations for Low-
Income Americans, J. Benefit-Cost Analysis (Nov. 16, 2021), https://tinyurl.com/3ndaupeh.
Commenters stated that these costs delaythe purchase of newvehicles, leaving older,
costlier vehicles on the road longer. See 85 FR 24626 (discussingthe effect of newvehicle
fuel economy and emissions standards on fleet turnover). Commenters stated that the EPA
has estimated the aggregate costs of this regulation at $1 trillion to date. Env'tl Prot.
Agency, EPA Releases Proposal to Rescind Obama-Era Endangerment Finding, Regulations
that Paved the Way for Electric Vehicle Mandates (July 29, 2025),
https://tinyurl.com/mva7umv3.
Some commenters argued that the Endangerment Finding has resulted in power generation
shifting to more expensive energy sources, and these new energy sources have lower
reliability, and that this reduced reliability and inability to use traditional energy sources
artificially restricts supply, further increasing costs and causing capital investments to be
allocated to low-carbon projects with higher costs and lower returns. Commenters argued
that the Endangerment Finding has also led to reduced consumer choice in the form of
higher costs for substitutable goods and mandates on manufacturers to produce low
carbon appliances and vehicles.
EPA Response
The EPA agrees with the commenters noting the significant economic consequences of the
Endangerment Finding. The Endangerment Finding, by triggering a duty to regulate,
imposed costs that were foreseeable and that the EPA at the time foresaw. See 73 FR
44354, 44355 (July 30, 2008) ("The potential regulation of greenhouse gases under any
portion of the Clean Air Act could result in an unprecedented expansion of EPA authority
that would have a profound effect on virtually every sector of the economy and touch every
household in the land."). Additionally, the Endangerment Finding acknowledged that
severing the findings and standards was a choice. As discussed in the preamble and
elsewhere in this RTC, treating it as a choice was improper under the best reading of the
statute. As such, it is also appropriate to considerthe economic impact of the standards
the EPA subsequently issued in concluding that the Endangerment Finding imposed
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significant costs. See RTC section 2.1.2.2.2 belowfora discussion of the economic
consequences of the EPA's GHG emission standards for motor vehicles.
EPA Summary of Comments
Other commenters said that the economic consequences of regulating GHGs under CAA
section 202(a)(1) do not implicate the major questions doctrine. They argued that the
potential for significant costs - including incidental and indirect costs - is inherent in
setting vehicle emissions standards, and Congress recognized and accepted as much
when it enacted Section 202(a). See Motor & Equip. Mfrs.Ass'n v. EPA, 627 F.2d 1095,1118
(D.C. Cir. 1979). In this context, commenters contend, significant consequences are not
enough to trigger the doctrine: there would have to be vast economic and political
consequences that are different in kind from the consequences of other types of emissions
regulations. Moreover, commenters argue, because the EPA is proposing that it has no
authority whatsoever to regulate GHGs under CAA section 202(a), it would not be enough
to show that some exercises of section 202(a) authority could have extreme political and
economic significance. Instead, commenters assert, the Agency would need to show that
every conceivable exercise of CAA section 202(a) authority to regulate GHGs would have
those consequences.
EPA Response
The EPA disagrees with the commenters and concludes that the Endangerment Finding
imposed significant economic consequences, as discussed in the final action preamble
and elsewhere in this document. The EPA also disagrees that it needs to demonstrate that
every conceivable exercise of its authority under its broader interpretation of CAA section
202(a)(1) would trigger the major questions doctrine in order for it to apply, as discussed
elsewhere in this document.
EPA Summary of Comments
Commenters also stated that the proposed Rule makes no effort to demonstrate that it is
impossible to set vehicle emissions standards for GHGs without imposing costs that are
different in kind than those associated with other standards. Commenters argued that any
attempt to do so would face the strong headwinds of 15 years of GHG vehicle emissions
standards, all concluding that the costs of regulating were reasonable and justified in light
of the countervailing benefits. See, e.g., 89 FR 27899-901. Commenters contend that
motor vehicle manufacturers have, in practice, adapted to those regulations and in any
event, standards designed to reduce GHG emissions are often based on technologies that
simultaneously reduce other types of pollutants. Commenters assert that the EPA could in
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many cases establish criteria pollutant standards based on the same technologies, such
as electric vehicles, regardless of whether the Agency may regulate GHGs. See 89 FR
28099; Light/Medium Duty Response to Comments 302-03; see also 65 FR 6746.
Commenters argue that these points are sufficient to defeat any argument that the
economic consequences of regulating GHGs are inherently different in kind than regulating
other pollutants emitted by vehicles. But because the proposal is so focused on the
particulars of the GHG standards the EPA has actually enacted, commenters state, it bears
noting that those specific standards do not impose the kinds of economic consequences
that trigger major-questions concerns.
EPA Response
As discussed elsewhere in this document, the EPA disagrees that its GHG emissions
standards did not impose significant economic consequences. Whether vehicle
manufacturers have adjusted the EPA's regulation of GHG emissions from motor vehicles
is immaterial and does not inform whether the Agency possesses the statutory authority to
regulate in the first instance. The EPA views the comment regarding establishing criteria
pollutant standards based on the same technology as out of scope for this rulemaking.
2.1.2.1.6 Political Consequences
EPA Summary of Comments
Some commenters argued that the Endangerment Finding and the EPA's regulation of
GHGs under CAA section 202(a)(1) were of vast political consequence. These commenters
noted that for decades, Congress had avoided thorny question of GHG regulation. These
commenters asserted that anthropogenic global warming had been a prominent national
and international issue since the 1980s, when scientific discussions about the possibility
of global climate change led to growing public concern both in the U.S. and abroad, yet
from the late 1970s through 2009, Congress repeatedly considered climate change
legislation, and consistently refused to authorize regulatory controls on GHG emissions.
EPA Response
The EPA agrees that the Endangerment Finding was of vast political consequences as
discussed in the final action preamble and elsewhere in this document.
EPA Summary of Comments
Commenters also said that political consequences of regulating GHGs under CAA section
202(a)(1) do not implicate the major questions doctrine. Commenters said that the EPA's
suggestion that the prominence of climate issues makes regulating GHGs too politically
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consequential is contrary to Supreme Court precedent recognizing the EPA's authority to
regulate GHGs in Massachusetts, AEP, UARG, and is contrary to the best reading of 202(a)
and a long chain of congressional and administrative action.
EPA Response
The Endangerment Finding, by triggering a mandatory duty to regulate GHG emissions from
new motor vehicles, attempted to solve an issue of vast political significance: how the
nation should respond to global climate change. Global climate change and how to
respond is the subject of earnest and profound debate across the country, both in 2009
and now. The EPA disagrees with the commenters' characterization of Massachusetts, AEP,
and UARG for the reasons discussed in the final action preamble and elsewhere in this
document. The EPA also disagrees with the assertion that its action is contrary to the best
reading of CAA section 202(a)(1) and congressional and administrative action as addressed
elsewhere in this document.
EPA Summary of Comments
Commenters also said that application of the major questions doctrine raises the
important question of how to determine when an executive branch assertion of authority
has vast economic and political significance. The Court has suggested that when the
executive branch exploits an ambiguity or gap in the law to take an action that Congress
would not have agreed to delegate, that may be indicative of political significance. One
commenter noted that opponents of federal regulation are attempting to capitalize on the
failed-legislation argument in litigation challenging an EPA rule that regulates GHG
emissions from cars and trucks under the CAA. See Initial Brief for Private Petitioners at 56,
Texas v. EPA (No. 22-1031) (D.C. Cir., Nov. 3, 2022) (citations omitted),
https://www.courtlistener.com/recap/gov.uscourts.cadc.38471/gov.uscourts.cadc.38471.1
208467839.1_2.pdf#page= 56. These commenters stated that before the DC Circuit,
petitioners argued that both Houses of Congress have previously considered and rejected
multiple bills will similar effects to the EPA's rule, and that this argument encourages the
court to accept the notion that when Congress does not enact an introduced bill, Congress
has rejected that bill. These commenters argue that this is not an accurate way to identify
rejected legislation - if rejected legislation is a key trigger for understanding where the
major question doctrine should be applied, then the history suggests that the EPA's
proposal to rescind the GHG vehicle standards would be a better candidate for the
doctrine than the established rules the agency now seeks to repeal. Commenters stated
that Congress has conspicuously and repeatedly declined to enact legislative proposals
that rescind the GHG vehicle standards.
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EPA Response
The EPA notes that the Supreme Court has looked to whether Congress has considered
and rejected proposals to create a climate change program through legislation that the
agency is seeking to do through regulation in determiningthe political significance of the
agency's asserted authority. West Virginia, 597 U.S. at 731-32. As discussed in the final
action preamble in section V.B.1 and in section 2.1.2.1.3 of this document, from 2007 to
2009, Congress considered legislation - supported by the President and Administrator in
office at the time of the Endangerment Finding - that would have authorized or required the
EPA to prescribe emissions regulations for GHGs. For example, the Safe Climate Act of
2007 would have adopted findings and policies with respect to limiting global temperature
increase, required various forms of international cooperation, and added a new title VII to
the CAA instructing the EPA to achieve phased GHG emission reduction targets and
regulate GHG emissions under CAA section 202. Similarly, the American Clean Energy and
Security Act of 2009 would have required international cooperation and added new titles to
the CAA requiring the EPA to, among other things, regulate GHG emissions under CAA
section 202. Neither bill was enacted through the legislative process, and Congress has
since declined to adopt similar legislation. This legislative history emphasizes the political
significance of the EPA's attempt to achieve through regulation what Congress has
declined to enact through legislation.
2.1.2.2 Applicability of MQDto 2024 Vehicle Rules
EPA Summary of Comments
Some commenters said that they support the EPA's application of the major questions
doctrine to the vehicle standards that effectively mandated EVs as a purported emissions
control measure for motor vehicles powered by internal combustion engines. They stated
that as the EPA points out in the Proposed Rule, effectively mandating a shift away from
internal combustion engine vehicles under CAA section 202(a) is conceptually
indistinguishable from the EPA's failed attempt to mandate generation shifting by reduced
utilization of coal-fired power plants under CAA section 111. Commenters argued that both
actions involve claims of novel and expansive regulatory authority under longstanding law,
both have fundamental effects on key national industries and on the national economy,
Congress has grappled repeatedly over time with whether and how GHG emissions from
these industries should be regulated, and neither action is grounded in a clear statutory
mandate.
Commenters also said that the Phase 3 Standards, without question, meet all the criteria
for rescission underthe major questions doctrine. Indeed, they argued, the Supreme Court
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in West Virginia v. EPA, 597 U.S. 697 (2022), has held open the door for the rescission of
sweeping ZEV-truck mandates that impact broad segments of the national economy.
Commenters argued that the Phase 3 GHG Standards are a direct analogue to the
regulations invalidated in West Virginia.
Commenters stated that in its GHG emission standards, just as in West Virginia, the EPA
claimed the power to effect a wholesale shift in energy policy: moving the Nation's light-,
medium-, and heavy-duty vehicle fleets from vehicles powered by internal-combustion
engines ("ICEs") that use liquid fuels to vehicles powered by battery-operated electric
motors. Commenters stated that at a more specific level, the Supreme Court in West
Virginia identified several clues from the statutory and regulatory scheme indicating that
the EPA needed clear congressional authorization for its Clean Power Plan, and that those
same clues are present in the EPA's emission standards. Commenters argued that the
lesson should be unavoidable: the EPA needs clear support from Congress to redefine the
source and replace the kind of vehicles America drives on its roads and uses for work and
delivery of goods that keep the economy running. Through its emission standards,
commenters argue, the EPA has claimed the power to radically change numerous sectors
in the economy that depend on LDVs, MDVs, and HDVs alike, including for every day
personal transportation and for services that deliver goods, supplies and equipment
throughout the country, as well as the numerous sectors that depend on the liquid fuels
(and related byproducts) on which such vehicles currently run.
Commenters also stated that forced electrification is inconsistent with legislation
Congress has enacted relating to transportation fuel and the environment. See UARG, 573
U.S. at 321. Commenters argued that the statutory scheme addressing GHG emissions
from the transportation sector shows a preference for continued reliance on conventional
vehicles powered by liquid fuels and promotion of corn ethanol and other biofuels, which
are used in conventional vehicles and which - unlike electric-vehicle components - can be
sourced domestically. See, e.g., I.R.C. § 40A (as amended by Pub. L. No. 117-169,136 Stat.
1932 § 13202, (2022)); id. § 45V (as amended by Pub. L. No. 117-169, 136 Stat. 1935-41, §
13204 (2022)); 7 U.S.C. § 8103 (as amended by Pub. L. No. 117-169, 136 Stat. 2020, § 22003
(2022)). Commenters contended that forcing electrification is at cross-purposes with Title
ll's Renewable Fuel Standard Program; the obvious reason for the mismatch is that
Congress has not decided to mandate electrification - nor has it placed that power in the
EPA's hands. See West Virginia, 142 S. Ct. at 2633 (Kagan, J., dissenting) (noting that when
the agency's "action, if allowed, would have conflicted with, or even wreaked havoc
on, Congress's broader design" it should not be allowed based on normal statutory
interpretation of a broad delegation of authority).
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Commenters stated that skepticism is warranted when an agency asserts an "unheralded
power representing a transformative expansion in its regulatory authority." West Virginia,
142 S. Ct. at 2610 (internal quotation marks omitted). Commenters further stated that
previously, to the extent the EPA addressed electric vehicles, it treated them as a
compliance "option" or "flexibility." They stated that up through the 2021 GHG standards
for LDVs, the EPA claimed that manufacturers could comply without using EVs, though
electrification was an option. Commenters stated that for subsequent standards, however,
the EPA's modeling clearly demonstrated that OEMs were expected to comply by increasing
production of battery electric vehicles (BEVs) and fuel cell electric vehicles (FCEVs) while
phasing out production of ICEVs. Commenters argued that indeed, forced electrification
had never before even been on the table for MDVs (and other HDVs), nor had the EPA
previously utilized its criteria pollutant standards in a thinly-cloaked strategy to
disincentivize further ICEV production in favor of vehicle electrification, as it did in the
multi-pollutant standards for MY 2027 and beyond.
EPA Response
The EPA concludes that the major questions doctrine applies to the GHG emissions
standards for light-duty, medium-duty, and heavy-duty vehicles that the Agency
promulgated in 2024, as discussed in the final action preamble and elsewhere in this
document.
To show how important the Endangerment Finding was, it led to a series of EPA GHG
vehicle regulations that pushed an EV mandate. Before the 2024 GHG regulations resulted
in an assumed compliance pathway that would require over 50 percent of new vehicles
being EVs, in 2010 the EPA explicitly expressed a desire to push EVs despite market
preferences. The EPA did not finalize as proposed a credit multiplier applying to EVs due to
adverse comments.
For example, in 2010, the EPA's final rule states:
EPA is finalizing provisions that provide a temporary regulatory incentive for
the commercialization of certain advanced vehicle power trains—electric
vehicles (EVs), plug-in hybrid electric vehicles (PHEVs), and fuel cell vehicles
(FCVs).... The purpose of these provisions is to provide a temporary incentive
to promote technologies which have the potential to produce very large GHG
reductions in the future, but which face major challenges such as vehicle cost,
consumer acceptance, and the development of low-GHG fuel production
infrastructure. . . . EPA notes that EVs, PHEVs, and FCVs are potential GHG
"game changers" if major cost and consumer barriers can be overcome and if
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there is a nationwide transformation to low-GHG electricity (or hydrogen, in
the case of FCVs).26
The EPA continued use of the "game changer" terminology in the 2012 final rule, this time
establishing the credit multiplier for EVs the Agency had contemplated in the 2010 rule:
In orderto provide temporary regulatory incentives to promote the penetration
of certain "game changing" advanced vehicle technologies into the light duty
vehicle fleet, EPA is finalizing, as proposed, an incentive multiplier for C02
emissions compliance purposes for all electric vehicles (EVs), plug-in hybrid
electric vehicles (PHEVs), and fuel cell vehicles (FCVs) sold in MYs 2017
through 2021. The incentives are expected to promote increased application
of these advanced technologies in the program's early model years, which
could achieve economies of scale that will support the wider application of
these technologies to help achieve the more stringent standards in MYs 2022-
2025.27
This is a clear example of the EPA utilizing the authority under section 202(a) to force a shift
by providing a multiplier that is not tied to GHG emissions but to force "game changing"
non-ICE vehicles technologies as part of the regulatory regime. Additionally, the EPA took
into account the multiplier when establishing GHG emission standards in their regulations.
EPA Summary of Comments
Some commenters stated that the major questions doctrine did not apply to the 2024
standards and the EPA has not explained or shown awareness of its complete change in
position from its detailed consideration and rejection of the same major questions doctrine
arguments last year in its 2024 rulemakings. Commenters raised that the EPA previously
distinguished West Virginia and UARG from its 2024 vehicle rules, that the Inflation
Reduction Act supported the EPA's authority, that there's no inconsistency between
regulating GHGs under section 202(a)(1) and the RFS program, that the CAA authorizes the
EPA to consider electrification technologies when it sets standards under section 202(a)
and that consideration of those technologies is not a transformation of the EPA's well-
established authority, that the 2024 regulations imposed an "EV mandate," and that
Congress vested the EPA authority to adopt regulations that would have an indirect effect
on the demand for oil and gas.
EPA Response
26 75 FR 25434, 25436 (May 7, 2010).
27 77 FR 62624, 62629 (Oct.15, 2012).
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The EPA acknowledges that it had previously asserted that the 2024 vehicle standards did
not violate the major questions doctrine; however, it now believes that is no longer the
case. The arc of regulation since the EPA issued the Endangerment Finding in 2009,
culminating in the 2024 rules, evidences an effort to accelerate the transition to EVs.
Accelerating the transition to EVs is realistically the only way to have any chance of
addressingthe dangers identified in the Endangerment Finding given the nature of the
problem. As discussed in the final action, even a complete elimination of all GHG
emissions from new motor vehicles and engines would not address the risks attributed to
elevated global concentrations of GHGs.
At least two auto manufacturers noted the compliance challenges with the current
standards and cast doubt on their attainability, particularly in light of reduced EV demand.
Toyota commented: "In short, the GHG and criteria pollutant standards in the
Multipollutant final rule combine to form a back-door electric vehicle (EV) mandate at
levels Toyota believes are not feasible in today's market. For example, by 2032 MY, the light-
duty GHG standards project a 70% EV market share... Today's 9.5% EV market share must
triple by 2027 MY and grow seven-fold by 2032 MY to meet EPA's projected range assumed
for compliance. Such aggressive growth is extremely unlikely and is further challenged by
the elimination of various EV tax credits upon which the Multipollutant final rule heavily
relied." Similarly, Ford commented that: "Leading up to the 2027MY and beyond GHG
programs, EPA's 2023-2026 standards were themselves already very challenging, with year-
over-year stringency increases of 5-10%, far outstripping the historical trend of roughly 1-
2% improvement in internal combustion engine vehicle GHG emissions. This is creating a
large compliance shortfall for the industry even before reaching 2027MY, and Ford supports
stringency relief for these earlier model years. Given the current state of the EV market,
Ford also believes the 2027MY and beyond GHG standards are infeasible and inappropriate
across the light-, medium-, and heavy-duty vehicle classes and supports a reduction in the
stringency of the standards finalized in the MPR and HD GHG Phase 3 rules." As
demonstrated by these manufacturers' comments, the EPA's GHG emissions standards are
likely difficult to achieve without increasing EV production.
Further, certain events have overtaken aspects of the EPA's analysis in its prior
rulemakings. For example, the Inflation Reduction Act was largely overtaken by the OBBBA,
and Congress has disapproved of the EPA's approval of the California waiver under the
CRA. The market has also changed since the 2024 rule: EV demand is down, gas prices are
generally down and EV prices are generally higher than the EPA originally approximated.
See, e.g., Regulatory Impact Analysis ch. 2.
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In effect, the main compliance option for the EPA's GHG emissions standards was for
manufacturers to increase EV production. As discussed in greater detail below, the EPA
first incentivized EV production in 2010 and projected that compliance with many of its
standards in the years since then would include surpassing the amount of EVs that
manufacturers would have produced based on market forces alone. Additionally, during
this time the EPA approved waivers allowing California to implement an EV mandate, an
additional EPA action contributing to the trend towards increasing EV production. See, e.g.,
90 FR 642 (Jan. 6, 2025) (the EPA's decision granting CARB's request for a waiver of CAA
preemption for its Advanced Clean Cars II regulations); see generally
https://www.epa.gov/state-and-local-transportation/vehicle-emissions-california-waivers-
and-authorizations. The totality of the EPA's actions, when viewed holistically, show a clear
path towards a changed reality on the ground of more EVs.
2.1.2.2.1 The 2024 vehicle rule was an unheralded and transformative use
of agency power
EPA Summary of Comments
Commenters said that as in West Virginia, the EPA cannot unilaterally reshape the
transportation and goods movement sectors in such a manner by unilaterally expanding its
statutory authority. Commenters contended that MDHD vehicles transport students and
commuters, move consumer goods across the country, deliver ourfood and medicines,
remove garbage and snow, and otherwise quite literally drive our national economy. As a
result, commenters state, the question of whether and how ICE-powered trucks should be
phased-out in favor of electric vehicles is thus consequential - it involves millions of jobs,
the restructuring of entire industries, and directly impacts the nation's energy
independence. Commenters argue that if the federal government is going to require that
major shift, then Congress, not the EPA, must say so.
Commenters further said that to force electrification, the EPA would need to understand
and weigh "many vital considerations of national policy." l/l/esf Wrg/'n/'a, 142 S. Ct. at 2612.
They stated that the policy judgments here involve not only climate impacts but millions of
jobs, the restructuring of entire industries, the Nation's energy independence and
relationship with hostile powers, and supply-chain and electric-grid vulnerabilities, and
that the EPA does not have any expertise in those matters. Commenters stated that the
judgments here are not ones "Congress presumably would" entrust to "an agency [with] no
comparative expertise," but are "ones Congress would likely have intended for itself." West
Virginia, 142 S. Ct. at 2612-13.
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Commenters also asserted that the EPA is not the expert in setting fuel economy
standards, but it is in effect setting fuel economy standards through its GHG vehicle
standards. Commenters argued that the EPA's lack of comparative expertise in setting fuel
economy standards and NHTSA's unquestioned exclusive role and expertise on such
standards is yet another factor showing the EPA's GHG vehicle standards violate the major
questions doctrine.
Some commenters argued that the EPA's previous vehicle rules were transformative, and
that nothing in Section 202(a) allows the EPA to transform the automotive industry any
more than the EPA was authorized to transform the electric power industry. In fact,
commenters contended, the electric vehicle mandate in the Multipollutant Heavy-Duty
Rules is more ambitious than the Clean Power Plan regulations because it reaches a
broader swath of the economy- millions of vehicles for personal use and commercial
vehicles such as for interstate trucking (which affects nationwide inflation for basic
consumer goods, includingfood, clothing, and electronics). Commenters stated that the
rules would also require a rapid buildout of electric generation infrastructure, including
new generating units and transmission lines, at a pace beyond what is feasible without, at
least, Congress granting such projects broad waivers from environmental permitting and
review requirements. Simply put, commenters argue that implementing the electric vehicle
mandate on the timeline set out in these rules would require a nearly unprecedented
national effort, without a word of approval from Congress, much less proper consideration
of the logistical, permitting, and site access realities that make such a buildout infeasible
without supportive Congressional action.
One commenter stated that the EPA believes it can use its standard-setting authority not
only to set requirements for new truck emissions, but also to set requirements for the very
design and power sources for new trucks going forward. Commenters stated that the
"breadth of the authority that [the EPA] has asserted" is so broad that it provides all the
more "reason to hesitate before concluding that Congress meant to confer such authority."
Commenters stated that in West Virginia, the Court found it significant that the EPA's rule
would put the agency in the position of "balancingthe manyvital considerations of national
policy implicated in the basic regulation of how Americans get their energy." 142 S. Ct. at
2612. Commenters contended that the Court was concerned that the agency would decide
"how much of a switch from coal to gas" the grid could tolerate, and "how high energy
prices [could] go" before becoming "exorbitant." Id. Here, too, commenters argue, the EPA's
emission standards that it proposes to rescind put it in the position of deciding"how much
of a switch" to electrification the nation's power grids can tolerate, and how high vehicle
and electricity prices can climb without being "exorbitant." Commenters also state that the
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EPA's previously asserted authority also implicates another key "consideration[] of national
policy": national security. Co mm enters state that NHTSA has acknowledged that the
United States "has very little capacity in mining and refining any of the key raw materials"
for electric vehicles. 86 FR 49,602, 49,797 (Sept. 3, 2021). Commenters state that unlike
biofuels and petroleum, most of the supply of critical components of batteries and motors
for electric vehicles is controlled by hostile or unstable foreign powers, in particular China.
Commenters state that shifting to electric vehicles would thus make the American
automotive industry critically dependent on one of the Nation's primary geopolitical rivals.
EPA Response
The EPA concludes that its vehicle standards were a transformative use of its authority
under CAA section 202(a)(1), as discussed elsewhere in this document.
EPA Summary of Comments
Other commenters asserted that setting standards based on increased electrification is
not transformational, and that the EPA's 2024 vehicle emissions standards specifically was
not transformative and was supported by regulated industry.
Commenters also said that the vehicle GHG standards were a straightforward application
of section 202(a), employingthe same regulatory approaches and the same consideration
of all applicable technologies, that the EPA has exercised under that provision for decades.
Commenters stated that the standards are imposed on the same class of entities as prior
section 202(a) emission standards; they involve the same sort of policy judgments as
previous standards under section 202(a); and they do not impose demands of a
significantly different character from those traditionally associated with section 202(a)
regulations.
Commenters also contended that the CAA has long been understood to promote the
application of a range of possible approaches to controlling emissions. They stated that the
EPA's consideration of EVs in the standards was rooted in a long-standing approach that
looked beyond end-of-tailpipe controls. Commenters argued that CAA motor vehicle
emissions controls have long recognized that reductions may come from the means of
propulsion, and that indeed, the EPA has considered EVs in every 202(a) rulemaking since
2000. Commenters state that prior standards acknowledged technological developments
such as increasing vehicle hybridization and techniques like engine shut down while idling
as a potential compliance solution.
Commenters also argued that while the standards may motivate automakers to increase
their production of electric vehicles, this is a performance standard where manufacturers
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retain substantial flexibility in how to comply. Commenters contended that it would be
feasible to meet the standards without additional zero emission vehicles beyond the
volumes already sold, and that the standards merely enhance the stringency of vehicle
emissions control requirements to reflect new developments of technology. As such,
commenters argue, these standards do not represent an EPA exercise of unheralded
power. Commenters further stated that the regulations were technology-neutral and did
not prescribe any particular technology solution and allowed automakers to choose the
best strategy for themselves to meet the fleet-average emissions rate target.
Commenters argued that as the EPA extensively documented in its prior rulemaking, and
as evident in the legislative history and DC Circuit caselaw, Congress understood and
expected that internal combustion engines would eventually need to be replaced, likely by
electric vehicles. Commenters state that, as the DC Circuit noted in International
Harvester, contemporaneously with the CAA of 1970, "it is the belief of many experts-both
in and out of the automobile industry-that air pollution cannot be effectively checked until
the industry finds a substitute for the conventional automotive power plant-the
reciprocating internal combustion {i.e., 'piston') engine. It is clear from the legislative
history that Congress expected the Clean Air Amendments to force the industry to broaden
the scope of its research-to study new types of engines and new control systems."
EPA Response
The vehicle standards reflect an increasing trend towards a transition to EVs for nearly all
classes of LD, MD, and HD vehicles. As discussed in 2.1.2.1.2, given the regulatory history
of 202(a)(1), this trend reflects the novelty and transformative nature of the vehicle GHG
standards. Before the Endangerment Finding and vehicle standards, the EPA did not
incentivize or force a transition towards EVs in response to global climate change
concerns.
The EPA first introduced electrified technologies as a means of reducing GHG emissions in
its Light-Duty Vehicle GHG emissions standards and CAFE standards in 2010. 75 FR 25324.
"Although many of these technologies are available today, the emissions reductions and
fuel economy improvements finalized in this notice will involve more widespread use of
these technologies across the light-duty vehicle fleet. These include improvements to
engines, transmissions, and tires, increased use of start-stop technology, improvements in
air conditioning systems, increased use of hybrid and other advanced technologies, and
the initial commercialization of electric vehicles and plug-in hybrids." 75 FR at 25328. The
EPA also finalized a provision in 2010 that incentivized advanced technologies, including
EVs: "EPA is providing an additional temporary incentive to encourage the
commercialization of advanced GHG/ fuel economy control technologies - including
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electric vehicles (EVs), plugin hybrid electric vehicles (PHEVs), and fuel cell vehicles (FCVs)
- for model years 2012-2016." Id. at 25341. Further, the "EPA also recognizes that this rule
would enhance the development and limited use of more advanced technologies, such as
PHEVs and EVs." Id. At 25404. While the EPA anticipated that EVs would play an increasing
role in reducing GHG emissions and included an incentive for manufacturers to produce
EVs, our final technology penetration projections did not include EVs to meet the 2012-
2026 FHF emission standards in the 2010 rulemaking.
In the EPA's next light-duty rule for MY 2017 and later, the EPA continued to provide
incentives for EVs: "In order to provide temporary regulatory incentives to promote the
penetration of certain "game changing'" advanced vehicle technologies into the light duty
vehicle fleet, EPA is finalizing, as proposed, an incentive multiplier for C02 emissions
compliance purposes for all electric vehicles (EVs), plug-in hybrid electric vehicles
(PHEVs), and fuel cell vehicles (FCVs) sold in MYs 2017 through 2021." 77 FR at 62628. The
EPA projected that electrified technologies would continue to penetrate the light-duty
vehicle fleet: "For example, while today less than three percent of annual vehicle sales are
strong hybrids, plug-in hybrids and all electric vehicles, by MY 2025 we estimate in our
analyses for this final action that these technologies could represent 3-7%...". The final
projected EV penetrations were generally limited to smaller volume manufacturers:
Daimler at 7%; Ferrari at 16%; Volvo at 6%; and Mazda at 12%. Id. at 62632 n.23. The EPA
continued to incentivize EVs, though EV penetrations were still expected to be modest in
the MY2017 rulemaking.
In the mid-term evaluation of GHG emissions standards for MY 2022-2025 for light duty
vehicles, the EV projected fleet average of EV penetration for cars ranged from 1.6% (GM) to
29.9% (Jaguar-Land Rover). EPA Draft Technical Assessment Report: Midterm Evaluation of
Light-Duty Vehicle Greenhouse Gas Emission Standards and Corporate Average Fuel
Economy Standards for Model Years 2022-2025 (July 2016), p.12-27, available at
https://nepis.epa.gov/Exe/ZyPDF.cgi/P1 OOOXEO.PDF?Dockey=P1 OOOXEO.pdf. For trucks
the fleet average was 0.4% with Subaru at 1.7%, Mazda at 1.3% and Honda at 1.0%. Id. at
p.12-28. The EPA concluded "For some manufacturers, strong electrification is expected to
be utilized, however, for the overall fleet EPA has projected a minimal amount of strong
electrification technology penetration." Id. at p.12-25.
In the 2023 and later rulemaking, EV projections started to increase significantly to meet
MY2026 standards. The projected fleet penetration for BEVs and PHEVs rose to 17% in
MY2026. As we concluded at the time:
"The pace of introduction of new EV and PHEV models is rapidly increasing. For
example, the number of EV and PHEV models available for sale in the U.S. has more
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than doubled from about 24 in MY 2015 to about 60 in MY 2021.117 Even under the less
stringent SAFE standards, manufacturers have indicated that the number of EV and
PHEV models will increase to more than 80 by MY 2023, with many more expected to
reach production before the end of the decade.118
Despite the increased penetration of electrified vehicles that we are projecting for the
final standards, the large majority (more than 80 percent) of vehicles projected to be
produced by manufacturers in complying with the final standards would draw from the
various advanced gasoline vehicle technologies already present in many vehicles within
today's new vehicle fleet. This projection is consistent with the EPA's previous
conclusions that a wide variety of emission reducingtechnologies are already available
at reasonable costs for manufacturers to incorporate into their vehicles within the
timeframe of the final standards.
Although the projected penetrations of BEVs and PHEVs are higher than in the proposal,
we find they more accurately reflect the current momentum and direction of
technological innovation in the automotive industry. By all accounts, a shift to zero-
emission vehicle technologies is well underway, and it presents a strong potential for
dramatic reductions in GHG and criteria pollutant emissions. Major automakers as well
as many global jurisdictions and U.S. states have announced plans to shift the light-
duty fleet toward zero-emissions technology.
As noted in the proposed rule, a proliferation of recent announcements from
automakers signals a rapidly growing shift in investment away from internal-
combustion technologies and toward high levels of electrification.
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Company
BEV+PHEV Penetration Rate in MY 2026
(% of sales)
BMW
22
Daimler
36
FCA (Stellantis)
18
Ford
18
General Motors
16
Honda
14
Hyundai Kia-H
19
Hyundai Kia-K
9
Jaguar Land Rover
34
Mazda
17
Mitsubishi
10
Nissan
15
Subaru
1
Tesla
100
Toyota
12
Volvo
20
VW
21
Total
17
86 FR at 74485-86, Table 33. Although we projected a significant increase in electrification
to meet the revised MY2026 standards, advanced gasoline technologies were still expected
to carry most emissions reductions.
Most recently, the multi-pollutant emissions standards for model years 2027 and later
projected a significant increase in BEV penetration to meet the MY 2032 GHG standard. 89
FR 27842. Similar to the MY 2023 rule, the EPA relied on manufacturer statements
regarding increased electrification of their products and the Inflation Reduction Act
incentives for manufacturers and purchasers of EVs. See, e.g., id. at 27846-52. The EPA
analyzed three main compliance scenarios: Pathway A- Higher BEV (central case), which
relied primarily on the penetration of BEV's to meet the MY 2032 standards. Pathway B -
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Moderate HEV and PHEV Pathway, increased the reliance on hybrid and plug-in hybrid
vehicles to meet the standards. Pathway C - Higher HEV and PHEV Pathway, which put the
lowest emphasis on BEV penetrations. Id. at 27855-56. The results for MY 2032 are shown
below for these scenarios:
Pathway
Technology
2032 (percent)
Pathway A - Higher BEV
ICE
29
HEV
3
PHEV
13
BEV
56
Pathway B - Moderate HEV
and PHEV
ICE
21
HEV
6
PHEV
29
BEV
43
Pathway C - Higher HEV
and PHEV
ICE
17
HEV
13
PHEV
36
BEV
35
Id. at 27856, Table 3. The EPA recognized that the standards are performance based and
that multiple technology pathways existed to meet the new standards; but our analysis
projected a significantly higher penetration of BEVs in MY 2032 across all scenarios. MY27
and later resulted in more significant EV penetration and went beyond what manufacturers
would have produced but for our regulation.
For heavy-duty vehicles, EVs could be used to comply beginning with HD GHG Phase 1,
with the first standards taking effect in MY 2014. 76 FR 57106. The first time we used EVs in
our feasibility assessment for setting GHG standards was with HD GHG Phase 3 (2024 rule)
which takes effect in MY 2027. 89 FR 29440.
As this history shows, the EPA has considered EVs as a means of reducing GHG emissions
as early as its first GHG emissions standards rulemaking and incentivized their
development. For example, this is clear from our 2012 projection that EVs, hybrids, and
plug-in hybrids could represent 3-7% of the vehicle fleet to our 2024 projection that BEVs
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could represent anywhere from 35 to 56% of the light-duty vehicle fleet. These rules were
the predictable outcome of the Endangerment Finding and demonstrate that through the
GHG emission standards for motor vehicles, the EPA increasingly trended towards
mandating a shift from gas- and diesel-fueled vehicles to EVs.
EPA Summary of Comments
Commenters also argued that the vehicle GHG standards were not based in a subtle
device that had rarely been used in the preceding decades, nor did the EPA's authority
depend upon a strained understanding of the statute. They argued that the EPA's authority
to promulgate GHG standards is grounded in core provisions of the CAA that are written in
starkly broad terms and that speak directly to the agency's mandate to regulate air
pollutant emissions from new motor vehicles that endanger public health or welfare,
including through effects on climate. Commenters contended that setting standards based
on increased electrification is not transformational, nor would stripping the EPA of its
authority to regulate GHGs under section 202(a) prevent the adoption of future standards
relying on electrification. Commenters stated that increased electrification is an effective
technology for reducing many regulated pollutants, not just GHGs.
Commenters said that West Virginia is distinguishable because vehicle standards based on
increased electrification are run-of-the-mill technology-based standards. Commenters
argued that batteries or other technologies that run in whole or part on electricity are an
available technology that can be incorporated into an individual vehicle to make it run more
cleanly, and increasing electrification to reduce or eliminate emissions caused by burning
gasoline has been part of the EPA's toolkit since well before the Endangerment Finding.
Commenters contended that the possibility that more stringent vehicle emissions
standards could lead to greater use of electrification technology in vehicles and potentially
decreased use of internal combustion engines was understood by Congress as early as the
1960s, including the Senate report accompanying the 1970 CAA amendments.
Commenters also argued that fuel switching motor vehicle standards are not an
extraordinary departure from the forms of regulation discussed at the time of the CAA's
passage. Commenters provided the following examples:
(1) In 1965, Frank Ikard, president of the American Petroleum Institute, spoke to
members at its annual meeting about the release of the President's Science
Advisory Committee ("PSAC") report, Restoring the Quality of Our Environment.
One of the report's most important predictions, Ikard said, was that "carbon dioxide
is being added to the Earth's atmosphere by the burning of coal, oil, and natural gas
at such a rate that by the year 2000 the heat balance will be so modified as possibly
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to cause marked changes in climate beyond local or even national efforts." He
further noted, quoting directly from the report, that a "nonpolluting means of
powering automobiles, buses, and trucks is likely to become a national necessity."
(2) In a July 16,1970, Executive Session on the CAA Amendments of 1970, Senator
Howard Baker spoke on the application of national air pollution standards: "[Y]ou
may have enormous unanticipated economic impact because there may be some
industry that can't continue to operate that will completely destroy the economy of
a particular city. I don't mean to imply that I think we shouldn't face that challenge if
we need to, but I think we need to be fully aware of what we are doing." Senator
Muskie replied, "when you take into account the very real questions that I am
beginningto have at least about the possibility of cleaning up the internal
combustion engine... you legitimately inquire as to whether or not you ought to be
finding the pressure point to develop other forms of power sources."
(3) In an August 4,1970, Executive Session on the CAA Amendments of 1970,
Senator Muskie noted that a draft version of section 202(a) "makes it possible or
gives the Secretary authority to, in effect, outlaw the internal combustion engine."
The staff director of the Senate Subcommittee on Air and Water Pollution, Leon
Billings, confirmed that by "giving the Secretary authority to prescribe a standard
which could not be met by the internal combustion engine, it would, in effect, give
him that authority, yes, sir. In other words, if it was technically feasible to design an
engine system which could result in a pollution-free vehicle, [the Secretary] found
that to be practicable, and promulgated it as a standard, and the internal
combustion engine couldn't meet it, then the internal combustion engine would
have to go by the board."
(4) Later in the August 4,1970 Executive Session, Senator Muskie phrased debate
over the language of section 202(a) as a question of "at what point should we require
or should we make it possible, let's put it that way, for the Secretary to shift, for the
country to shift, from the internal combustion engine to some other power source?"
(5) Senator Thomas Eagleton framed the challenge of drafting section 202(a) as
follows: "I think what we are striving toward is that over a period of time the vigorous,
alert, Secretary of HEW [a precursor to the EPA Administrator] would nudge, strongly
nudge, the industry away from internal combustion into Utopian engines." These
historical examples contradict the EPA's suggestion that regulations requiring shifts
in vehicle fuel sources are categorically impermissible under the CAA.
EPA Response
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The EPA disagrees with the commenters for the reasons addressed in the final action
preamble and elsewhere in this document. The Endangerment Finding and subsequent
GHG emissions standards were not based in the best reading of CAA section 202(a)(1). The
Agency further disagrees with the commenters' assertion that its vehicle standards were
not transformative, as discussed in the previous comment response.
2.1.2.2.2 The 2024 vehicle rules were ofvast economic and political
significance
EPA Summary of Comments
Some commenters argued that previous vehicle rules were of vast economic and political
significance, and as such, presented a major question. They contended that the economic
significance of the EPA's Phase 3 Standards is immense and that by the EPA's own
projection, the rule will cost vehicle manufacturers well over $20 billion through 2055.
Commenters assert that given the projected impacts of the rule, there can be "no serious
dispute" that the EPA is claiming "authority to exercise control over 'a significant portion of
the American economy.'" Commenters argue that the political significance of the EPA's rule
Phase 3 Standards is equally transformational and that whether to require greater
electrification of the MDHD vehicle market by government mandate is "the subject of an
earnest and profound debate across the country," and around the world. Commenters
assert that the EPA's Phase 3 Standards are also inconsistent with Congress' broader
statutory scheme for addressingvehicle emissions through renewable fuels.
Commenters also stated that the Multipollutant Rule sought to force a monumental shift in
consumer purchasing patterns overthe course of just a few years, given that not even one
in ten new car buyers purchase an electric vehicle. Commenters argued that the electric
vehicle mandate thus requires consideration of numerous issues of "vast economic and
political significance," including, but not limited to: (1) consumer resistance to vehicle
electrification, due in part to cost and the reduced flexibility of recharging electric vehicles
compared to internal combustion engine vehicles; (2) the need to rapidly construct
charging infrastructure, which has proven challenging; (3) the consequences of
dramatically reducing the existing gasoline infrastructure for vehicles and implications for
road construction and repair from reduced gasoline tax revenue; (4) the capacity for
existing electricity generation and transmission to accommodate a shift to an increasingly
electric fleet at the same time as artificial intelligence and data centers need substantial
new capacity; (5) foreign policy concerns related to the importation of critical rare earth
minerals; and (6) the practical difficulties of using electric vehicles for many applications,
such as in rural areas and in heavy-duty trucking.
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Commenters argued that at the threshold, the economic significance of the EPA's emission
standards that it proposes to rescind is staggering, in both its direct effects and the
implications of the authority the EPA claims. Commenters asserted that the EPA's prior
approach to setting the standards for LDVs, MDVs, and HDVs was plain - the standards
require replacing ICE vehicles with BEVs or FCEVs. Forcing such a transition, commenters
argued, has dramatic consequences, including increased consumer acquisition costs, lack
of adequate public and personal charging infrastructure (e.g., multi-family housing and
rural areas), increased charging times (particularly for those relying on public charging
stations), increased demand for electricity, increased wear on public roads from heavier
electric vehicles, and increased tire wear, among others.
Commenters further asserted that through its emission standards, the EPA
likewise sought to "substantially restructure" the American vehicle markets, and with
them, many sectors and supply chains in the U.S. economy. Commenters argued that the
overall cost and economic impact of this restructure is staggering - despite the EPA's prior,
gross understatements to the contrary. And they further argued that the EPA's failure to
consider the full extent of this economic impact in setting such standards is indicative of
its limited authority; if Congress truly meant to grant such an awesome power to the EPA, it
would not have restricted the EPA's cost considerations to vehicle manufacturers
only. Indeed, commenters argued that the effects of the EPA's standards extend well
beyond the vehicle manufacturing industry and personal, consumer use. Commenters
state that the standards will impact, among other sectors, the refining, agriculture, and
manufacturing industries, how and to what extent they operate, where they source their
supply chains, and how and whether they continue to produce products that are essential
to modern life, and will also impact the trucking hauling industry, how it operates, and how
it delivers goods around the country. Commenters argue that these impacts, in turn, will
have ripple effects throughout the economy, both with regard to supply chain costs and
availability and, ultimately, increased costs to consumers. Moreover, commenters
contend, many industries dependent upon the refining sector, such as the asphalt,
petrochemical and sulfur industries (all of which are, ironically, essential to increased EV
production), will see their supply chains reduced and prices increased to the extent the
proposal reduces liquid fuel demand and, consequently, impacts refining.
Commenters also stated that Congress has recently set forth exactly what it thinks of the
Biden EPA's attempts to force electrification in a closely related area. They stated that by
using the CRA to disapprove three EPA waivers that would have allowed California to
impose similar EV mandates, Congress sent a clear signal that neither federal nor state
agencies should dictate consumer vehicle technology. Commenters stated that allowing
an agency to impose such mandates raises major economic and political questions
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regarding everything from the price of new cars to the stability of our national energy
infrastructure - questions that may only be decided by Congress.
Commenters stated that the target of the EPA's standards - to say nothing of climate
change more generally - is "the subject of an earnest and profound debate across the
country." West Virginia, 142 S. Ct. at 2614. Commenters state that Congress too continues
to debate this very issue, which makes the EPA's previous claim to policymaking authority
"all the more suspect." West Virginia, 142 S. Ct. at 2614; see FDA v. Brown & Williamson
Tobacco Corp., 529 U.S. 120,155 (2000). Commenters assert that Congress has yet to
reach an answer and instead remains in factfinding mode as it considers the benefits and
risks of electrification. Commenters state that Congress enacted the Infrastructure
Investment and Jobs Act of 2021, which requires several agencies - notably not the EPA - to
prepare three separate reports for Congress on the implications of electrifying the Nation's
vehicle fleet. Pub. L. No. 117-58, §§ 25006, 40435, 40436, 135 Stat. 429, 845-49, 1050
(2021) (requiring reports on "the cradle to grave environmental impact of electric vehicles"
and "the impact of forced labor in China on the electric vehicle supply chain," among other
things).
EPA Response
The EPA agrees that its vehicle standards were of vast economic and political significance,
for the reasons discussed elsewhere in this document.
EPA Summary of Comments
Other commenters stated that the impacts of the 2024 standards did not impose
economic consequences that would trigger MQD and were not of vast political
significance. Commenters said that the EPA makes no effort to demonstrate that it is
impossible to set vehicle emissions standards for GHGs without imposing costs that are
different in kind than those associated with other standards.
For economic impacts, commenters pointed to the EPA's analysis in 2024 concluding that
the average cost per vehicle in the final year of the phase-in fall within the range of prior
rules and are relatively small to what Congress itself accepted in enacting CAA section
202. Commenters argued that for consumers, the lower operating costs for vehicles
substantially outweigh the increased technology costs of meeting the standards over the
life of the vehicles. Commenters contended that while the standards were expected to
cause indirect impacts, there is nothing different in kind about the impacts of the final
action compared to the impacts of prior rules; the presence of such impacts merely
reflects the ordinary nature of the global supply chain for motor vehicles. Commenters
argued that even if the EPA were to consider indirect regulatory impacts, the 2024 vehicle
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standards caused no significant indirect harms, has the potential for positive impacts, and
on balance provides positive net benefits to society. Commenters asserted that many of
the indirect impacts of the 2024 vehicle standards are close analogs of impacts Congress
recognized and accepted. Specifically, commenters pointed to the 2024 standards and
contend that they will not cause significant adverse impacts on electric grid reliability or
resource adequacy, that there will be sufficient battery production and critical minerals
available to support increasing electric vehicle production including due to large increases
in domestic battery and critical mineral production, that there will be sufficient lead-time
to develop charging infrastructure, and that the rule will have significant positive national
security benefits. Commenters asserted that the 2024 standards were expected to create
positive indirect impacts, includingthe significant benefits of mitigating air pollution
including both criteria pollutants, which contribute to a range of adverse effects on human
health including premature mortality, and GHGs, which contribute to climate change and
pose catastrophic risks for human health and the environment, water supply and quality,
storm surge and flooding, electricity infrastructure, agricultural disruptions and crop
failures, human rights, international trade, and national security, as well as reduced
dependence on foreign oil and increased energy security and independence, increased
regulatory certainty for domestic production of pollution control technologies and their
components and for the development of electric charging infrastructure, with attendant
benefits for employment and US global competitiveness in these sectors, and increased
use of electric charging and potential for vehicle-to-grid technologies that can benefit
electric grid reliability. Commenters argued that the 2024 standards would have estimated
annualized net benefits of $110 billion through the year 2055 when assessed at a 2 percent
discount rate (2022$).
EPA Response
The EPA concludes that the GHG emission standards for motor vehicles had vast economic
and political significance. Whether examining the amount of money involved for regulated
and affected parties, the overall impact on the economy, or the number of people affected,
the GHG emission standards have had vast economic consequences. As one commenter
noted, 90% of Americans own a motorvehicle. Another pointed to the importance of the
automobile industry to Americans, assertingthat cars and trucks are an $800 billion
industry that deliver freedom, mobility, and reliability as an integral part of American
society. Another raised that when the EPA initially established vehicle emissions standards
for GHGs followingthe Endangerment Finding, it identified $51.62 billion in anticipated
manufacturer costs over the succeeding five years. Env'tl Prot. Agency, Final Regulatory
Impact Analysis: Rulemakingto Establish Light-Duty Vehicle Greenhouse Gas Emission
Standards and Corporate Average Fuel Economy Standards 6-12 (Apr. 1, 2010) (identifying
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anticipated manufacturer costs of $4.94 billion in 2012, $7.96 billion in 2013, $10.34 billion
in 2014, $12.74 billion in 2015, and $15.64 billion in 2016). Further, the economic
consequences of the EPA's most recent rules were significant. Commenters noted the
EPA's 2024 vehicle standards would likely impose billions of dollars of costs on
manufacturers and consumers. The scale of these impacts demonstrates the economic
significance of the EPA's Endangerment Finding and subsequent GHG emission standards.
The EPA further concludes that its GHG emission standards for motor vehicles had vast
political consequences. As discussed in the final action preamble and elsewhere in this
RTC, how the Nation should respond to global climate change is the subject of profound
and earnest debate. Multiple instances of recent legislation addressing GHGs individually
and through distinct regulatory approaches suggests that Congress views such policy
decisions as economically and politically significant and not adequately addressed by
general statutory authorities enacted in response to different problems.
2.1.2.3 The Major Questions Doctrine does not preclude rescinding the
Endangerment Finding
EPA Summary of Comments
Some commenters said that if MQD is relevant here, its principles cut against the EPA's
novel interpretation of CAA section 202(a)(1). Commenters argued that for nearly 20 years,
Congress has declined to legislatively overturn any of the decisions upholding the EPA's
regulatory authority or to amend 202 to eliminate the EPA's broadly understood obligation
to promulgate GHG emission standards. Commenters contended that rescinding the
Endangerment Finding would itself create an abrupt reordering in an area of economic and
political significance and is an assertion of authority that would be both novel and dubious.
There was always an open question whether agency assertions of authority to sweep away
existing regulations could trigger MQD. Commenters also stated that the EPA's novel
attempt to rewrite the statute to fit the agency's policy preferences is a greater threat to
separation of powers.
Commenters asserted that under MQD, the EPA is not able to reverse its longstanding
interpretation in the Endangerment Finding without being given authority by Congress to do
so. Commenters stated that Congress has enacted numerous laws that have recognized
GHGs are air pollutants subject to regulation under the CAA. Commenters argued that
Massachusetts and the Endangerment Finding have been established law since 2009 more
than 15 years ago and that Congress has known about and enacted legislation on
numerous occasions that recognize and affirm the legal interpretations made in
Massachusetts and the Endangerment Finding.
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EPA Response
The EPA disagrees with commenters and concludes the major questions doctrine supports
the rescission of the Endangerment Finding and repeal of the vehicle standards. The EPA's
interpretation of CAA section 202(a)(1) is not novel; it was the agency's longstanding
application of the provision before 2009. Repeal of the standards does not trigger MQD as it
is not an unheralded assertion of regulatory authority. Rather, it is returning the agency to
its previous and better reading of its authority under section 202(a)(1). Because the EPA
concludes that the agency lacks statutory authority, the regulatory framework cannot stand
solely because parties have relied on it or because of their view of its importance.
Commenters inadvertently reinforce why the major questions doctrine applies to the
Endangerment Finding and necessitates its rescission. If rescindingthe Endangerment
Finding would trigger the major questions doctrine because of the significance of the EPA's
GHG regulatory framework for motor vehicles, then there would be no question that
imposing the Endangerment Finding triggered the doctrine in the first instance.
2.1.2.4The statute does not provide clear congressional authorization
EPA Summary of Comments
Commenters argued that the CAA does not provide clear congressional authorization for
the GHG emission standards. Commenters contended that as evidence that the judgments
here belong to Congress rather than the Executive, both Houses of Congress have
previously "considered and rejected" multiple bills with effects similar to the emission
standards the EPA proposes to rescind. West Virginia, 142 S. Ct. at 2614 (quotingBrown &
Williamson, 529 U.S. at 144). Commenters stated that Congress even rejected one bill that
would have mandated a level of electric-vehicle penetration roughly equal to the 50%-by-
2030 target the EPA embraced in its prior LDV/MDV standards. See, e.g., Zero-Emission
Vehicles Act of 2019, H.R. 2764, 116th Cong. (2019); ZeroEmission Vehicles Act of 2018, S.
3664,115th Cong. (2018); see also 116 Cong. Rec. 19238-40 (1970) (proposed amendment
to Title II that would have banned internal-combustion vehicles by 1978). Commenters
argued that Congress's "consistent judgment" against the very sorts of mandates imposed
by the EPA undercuts any claim of congressional authorization. Brown & Williamson, 529
U.S. at 147-48,160; accord West Virginia, 142 S. Ct. at 2614. Indeed, Commenters stated,
the U.S. House and Senate passed a joint resolution nullifying the EPA's rule on HDVs
relatingto air pollution, including ozone and particulate matter; the resolution was
subsequently vetoed by President Biden. Commenters stated that the fact that prior
administrations were required to rely on executive actions to force electrification of the
vehicle fleets demonstrates the lack of congressional authority.
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Commenters further stated that when Congress enacted the CAA in 1963 and later
amended it, debates over climate change were barely on its radar. See Massachusetts, 549
U.S. at 508-09. Instead, commenters stated, as the EPA recognized prior to the
Endangerment Finding, and as the pollutants specifically listed in the CAA reflect,
Congress was concerned with noxious substances (e.g., those that cause smog and acid
rain) which posed direct, immediate risks to human health and welfare. See 90 FR at
36,300. Commenters argued that while this authority did encompass certain secondary
pollutants like ground-level ozone, these secondary pollutants still resulted in direct
effects due to contamination.
EPA Response
The EPA agrees with the commenters that stated that Congress did not clearly authorize
the Endangerment Finding or the Agency's vehicle standards. The EPA's attempt to regulate
GHG emissions from motor vehicles to address global climate change concerns based on
statutory language authorizing the EPA to "prescribe...standards" is comparable to other
agency uses of broad statutory language found to insufficiently clear for major questions
doctrine purposes. See Nebraska, 600 U.S. at 506-07 ("the words 'waive or modify' do not
mean 'completely rewrite'; and that our precedent - old and new- requires that Congress
speak clearly before a Department Secretary can unilaterally alter large sections of the
American economy"); West Virginia, 597 U.S. at 720 ("the issue here is whether
restructuring the Nation's overall mix of electricity generation, to transition from 38% coal
to 27% coal by 2030, can be the 'best system of emission reduction' within the meaning of
Section 111"); Ala. Ass'n of Realtors, 594 U.S. at 764-65 (CDC's authority to adopt
measures "necessary to prevent the...spread of" disease did not authorize it to institute
nationwide eviction moratorium in response to COVID-19 pandemic). See also In re MCP,
2024 U.S. App. LEXIS 19815, *9-10 (6th Cir. 2024) ("The more an agency asks of a statute, in
short, the more it must show in the statute to support its rule. Net neutrality is likely a major
question requiring clear congressional authorization ... The Communications Act likely
does not plainly authorize the Commission to resolve this signal question. Nowhere does
Congress clearly grant the Commission the discretion to classify broadband providers as
common carriers. To the contrary, Congress specifically empowered the Commission to
define certain categories of communications services - and never did so with respect to
broadband providers specifically or the internet more generally."), aff'd on other grounds by
Ohio Telecom Ass'n v. FCC, 124 F.4th 993, 1009 (6th Cir. 2025) ("In sum, applying the plain
meaning of § 153(24) to the interconnected nature of the Internet, we conclude that
Broadband Internet Service Providers at the very least "offer[]" consumers the "capability"
of "retrieving" "information via telecommunications." Accordingly, the FCC's contrary
conclusion is unlawful. Given our conclusion that the FCC's reading is inconsistent with
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the plain language of the Communications Act, we see no need to address whetherthe
major questions doctrine also bars the FCC's action here."). In short, Congress has not
clearly authorized the agency to regulate GHG emissions from motor vehicles in response
to global climate change concerns through CAA section 202(a)(1).
See section 2.1.2.1.3 of this document for further discussion of failed legislative efforts to
regulate GHGs and other legislative developments relevant to the EPA's authority under
CAA section 202(a)(1) and the political significance of the EPA's assertion and exercise of
its authority in the Endangerment Finding and vehicle standards.
EPA Summary of Comments
Commenters asserted that even if the major questions doctrine applies here, CAA section
202(a) clearly authorizes the EPA to regulate GHG emissions from motor vehicles. They
contended that Massachusetts held that the CAA unambiguously authorizes the EPA to
regulate GHGs under Section 202(a); under Loper Bright, that is the single, correct meaning
of the statute and is not subject to revisiting by the EPA. Another commenter argued that
"clearly authorize" is not the correct standard and "best reading" of the statute is.
Commenters also argued that other CAA provisions further emphasize section 202's
application to GHGs. They argued that this most notably includes the CAA's definition of
"welfare," which includes "effects on soils, water, crops, vegetation, manmade materials,
animals, wildlife, weather, visibility, and climate." Commenters stated that the fact that
"welfare" as used in section 202 expressly includes climate impacts indicates that Section
202 encompasses pollutants that affect the climate. The fact that Congress was aware that
GHGs cause climate change when it enacted Section 202, commenters argued, only
further emphasizes that section 202 encompasses climate pollutants.
Commenters also stated that much of the justification in the proposal refers to the
administration's energy policy. The commenter represented the Court's opinion in Loper
Bright, 603 U.S. 369 (2024) as stating: "For policy goals not explicitly authorized by
Congress, agencies can no longer rely on a silent or ambiguous statute to justify their
actions. This shift has been described as reining in the regulatory reach of agencies." Also,
citing Nat'lAss'n of Home Builders v. Defenders of Wildlife, 551 U.S. 644 (2007),
commenters stated, "an agency has no power to 'tailor' legislation to bureaucratic policy
goals by rewriting unambiguous statutory terms. Agencies exercise discretion only in the
interstices created by statutory silence or ambiguity; they must always 'give effect to the
unambiguously expressed intent of Congress.'" Commenters argue that GHGs meet the
statutory definition of air pollutants and how they are a danger, which are the only statutory
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criteria. Commenters further argue that policy goals that conflict with statutory language
cannot be used to justify regulations.
Commenters also said that Congress issued a clear statutory command - here, in sections
202(a) and 302(h) of the CAA-yetthe executive seeks to avoid it, leaving courts to referee
conflicts that should never arise. Commenters said that by proposing to erase an
Endangerment Finding that Congress itself made unavoidable, the EPA is not exercising
discretion but asserting power to nullify a legislative mandate. Commenters state that that
is a direct affront to the separation of powers the Framers designed and that it signals to
the public that agencies can disregard Congress when inconvenient- a message
that corrodes both legal accountability and democratic trust. Commenters asserted that
the EPA must therefore explain how its rescission comports with Congress's unambiguous
command, or else admit it is claiming authority to override Congress outright. Commenters
contended that under Loper Bright, the agency does not receive Chevron deference; courts
will adopt the best reading of section 202(a) - a precautionary endangerment standard
Congress wrote. Commenters stated that the EPA must therefore identify a statutory hook
for rescinding the 2009 finding notwithstanding section 302(h)'s explicit inclusion of
climate in 'welfare,' or else concede it is asserting authority to negate a clear congressional
command.
EPA Response
The EPA disagrees with the commenters' arguments that Congress clearly authorized the
Agency to regulate GHG emissions from motor vehicles in response to global climate
change concerns through CAA section 202(a)(1) forthe reasons discussed in the final
action preamble and elsewhere in this document. The best reading of CAA section
202(a)(1), as informed by Loper Bright and principles of statutory interpretation, does not
authorize the EPA to assert jurisdiction over GHG emissions based on global climate
change concerns in a standalone Endangerment Finding. The EPA notes that one
commenter misattributed a quote to the Court's opinion in Loper Bright and partly
misattributed a quote from UARGXo Nat'lAss'n of Home Builders.
2.1.2.4.1 Constitutional concerns and nondelegation doctrine
EPA Summary of Comments
Commenters stated that resorting to MQD is not necessary to avoid constitutional
concerns. They contended that while some jurists have characterized MQD as a
presumption necessary to avoid nondelegation or other constitutional questions, that is
not the universal view of courts and regulating GHGs does not create constitutional
concerns.
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Some commenters raised constitutional concerns with the EPA's authority to regulate GHG
emissions. For conventional air pollutants with local effects or welfare impacts, such as
carbon monoxide, oxides of nitrogen, and particulate matter, commenters stated that
section 202 sets forth some intelligible principles. For example, commenters noted, it
directs the EPA to require heavy-duty vehicles or engines manufactured after 1983 to adopt
"standards which reflect the greatest degree of emission reduction achievable through the
application of technology which the Administrator determines will be available for the
model year to which such standards apply, giving appropriate consideration to cost,
energy, and safety factors associated with the application of such technology." 42 U.S.C. §
7521 (a)(3)(A)(i). Similarly, commenters stated, section 202 specifies how the EPA is to
classify vehicles, explaining that the EPA may consider "gross vehicle weight, horsepower,
type of fuel used, or other appropriate factors." Id. § 7521 (a)(3)(A)(ii). Commenters asserted
that other CAA provisions are likewise replete with language that serves to guide the EPA
decision-making. See, e.g., id. §§ 7409(b), 7411(b)(1)(A), 7412, 7511 b(f). Commenters
argued that when it comes to GHG emissions; however, section 202 provides far less
information about the general policy the EPA is to pursue and the boundaries of its
delegated authority. Commenters stated that section 202 does not specify the degree of
emissions reduction that the EPA is to achieve, the considerations that should inform any
standards, or how the resulting standards are supposed to work. Section 202(a)(1) simply
gives an open-ended command to adopt "standards," id. § 7521 (a)(1), commenters stated.
EPA Response
Regardless of whether MQD is a tool of statutory interpretation or a presumption to avoid
nondelegation issues, it applies to the Endangerment Finding. The best reading of the
statute articulated in the final action is necessary to avoid nondelegation issues, which is
further informed by the major questions doctrine. If CAA section 202(a)(1) is truly
unbounded by MQD, then the authority is boundless. In other words, if it is true that
Congress wanted to delegate an unbounded authority for the EPA to address any and all
problems that arise, then it violated the nondelegation doctrine.28 But it did not, for the
statutory reasons we offer and because, per the MQD, we do not presume that Congress
delegated major policy questions to agencies absent a clear statement.
EPA Summary of Comments
28 One commenter noted that at Least three Justices have expressed skepticism about the validity of the
intelligible principle standard to sufficiently safeguard against constitutionally impermissible delegations,
citing Justice Gorsuch's dissent, joined by Justices Thomas and Alito, in FCC v. Consumers' Research.
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Commenters disputed that a limited interpretation is necessary to avoid nondelegation
concerns. Commenters stated that CAA section 202(a) provides an intelligible principle
and thus does not pose a nondelegation problem. They argued that Congress provided the
EPA with sufficient direction about when and howto regulate under section 202(a).
Commenters contended that the EPA's limiting principle does not prevent uses of its
authority it now calls unduly broad. Citing Whitman v. American Trucking, at least one
commenter argued that the EPA cannot interpret away any potential nondelegation issue
as it is attempting to do in the proposed rule. Commenters argued that a potential rather
than actual nondelegation problem would not warrant invocation of constitutional
avoidance and that any hypothetical pollutant that the EPA would seek to regulate, like
water vapor or frisbees, would still need to meet the other statutory criteria for regulation
and be a reasonable exercise of the EPA's authority, one which would be subject to judicial
review.
Other commenters said that CAA section 202(a)(1) does not on its own provide an
intelligible principle to guide the EPA's discretion in prescribing GHG standards and on its
face is unconstitutional.
EPA Response
The EPA disagrees with the commenters' claim that regulating GHG emissions from motor
vehicles in response to global climate change under CAA section 202(a)(1) poses no
constitutional issues. A more limited construction of CAA section 202(a)(1) is the best
reading of the statutory text and is necessary to avoid absurd results and nondelegation
concerns. Commenters' interpretation, which was also the EPA's interpretation in the
Endangerment Finding, needlessly introduces a constitutional concern that can and
should be avoided. Commenters' arguments that there is an intelligible principle is not
consistent with their expansive interpretation of the condition that supposedly sets out the
principle.
The final action discusses what types of substances could be regulated under the
commenters' overly broad interpretation. For example, under this interpretation, the EPA
could attempt to regulate water vapor or nitrogen gas. Another commenter suggested that
GHG emissions have direct impacts by citingto cancer incidents near oil and gas facilities
and power plants, implying that CAA section 202(a)(1) can encompass GHGs based on the
entities involved in producing or utilizing them emitting other pollutants that have adverse
impacts, demonstrating the overbreadth of their interpretation.
The EPA continues to believe that its limiting principle is necessary, despite commenters'
assertion that the EPA's limiting principle is ineffective at preventing unduly broad uses of
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its authority. The central interpretation in this final action is that CAA section 202(a)(1) does
not authorize the EPA to regulate GHG emissions from motor vehicles in response to global
climate change concerns. In contrast to the EPA's expansive statutory interpretation of CAA
section 202(a)(1) in the Endangerment Finding, which contained the broadest, rather than
the best, interpretation of each relevant term in order to address global climate change, the
EPA's more limited statutory interpretation in this final action hews closely to that section's
central purpose of addressing local or regional, instead of global, exposure. Accordingly,
the EPA's views in this rulemaking do not affect our authority to regulate criteria pollutants.
GHGs differfrom criteria pollutants in how they each may endanger public health. In the
Endangerment Finding, the EPA found GHGs endanger through global-scale elevated
concentrations resulting in global temperature increases, sea level rise, and other
phenomena which in turn were asserted to play a causal role in environmental phenomena
with adverse impacts on public health and welfare - a long chain of causation, and
addressing that danger was always going to require getting towards zero emissions {i.e.,
EVs, given current and reasonably foreseeable technology). For criteria pollutants, the EPA
has found endangerment based on air pollution that itself endangers public health or
welfare through local or regional exposure. Accordingly, the endangerment can be
addressed through more measured reductions with many more options to address the
harm. In addition, Congress has added specific provisions for certain pollutants, like
criteria pollutants, into the rest of CAA section 202 that inform any use of 202(a)(1).
The EPA further disagrees with the suggestion that Whitman v. Am. TruckingAss'n, 531 U.S.
457 (2001) prevents our ability to invoke the principle of constitutional avoidance. Whitman
involved the Supreme Court's rejection of the D.C. Circuit's remedy. The D.C. Circuit held
that the "EPA had interpreted the statute to provide no 'intelligible principle' to guide the
agency's exercise of authority" and that "the EPA could perhaps avoid the unconstitutional
delegation by adopting a restrictive construction of § 109(b)(1)." 531 U.S. at 463. "[I]nstead
of declaring the section unconstitutional the court remanded the NAAQS to the agency." Id.
The Supreme Court disagreed on both fronts, holdingthat CAA section 109(b)(1) included
an adequate intelligible principle and that the D.C. Circuit had erred in remandingto the
agency for a limiting construction. Id. at 472-76.
In a nondelegation challenge, the question is whether Congress delegated legislative
power to the agency, not whether the agency can voluntarily limit itself to only exercising
delegated power to the constitutional limit. That is what the Court meant when it said: "We
have never suggested that an agency can cure an unlawful delegation of legislative power
by adopting in its discretion a limiting construction of the statute.... The idea that an
agency can cure an unconstitutionally standardless delegation of power by declining to
exercise some of that power seems to us internally contradictory. The very choice of which
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portion of the power to exercise - that is to say, the prescription of the standard that
Congress had omitted - would itself be an exercise of the forbidden legislative authority.
Whether the statute delegates legislative power is a question for the courts, and an
agency's voluntary self-denial has no bearing upon the answer." Id. at 474.
Here, the EPA asserts that the best reading of the statute is that it does not confer on the
EPA the discretion to regulate GHGs in response to global climate change concerns.
Constitutional avoidance is one reason to reach that conclusion; even if the statute were
ambiguous, the canon tells us to err on the side of avoiding constitutional concerns. This is
essentially the opposite situation as in Whitman. Commenters seems to assume that the
statute is unconstitutional. If that were the case, then a reviewing court should, per
Whitman, invalidate the statute rather than accept a limiting construction. But the statute
already includes a limiting construction that avoids nondelegation problems; the
Endangerment Finding and adverse commenters here are misreadingthe statute and
thereby introducing a potential constitutional flaw. See Edward J. DeBartolo Corp. v. Fla.
Gulf Coast Bldg. & Constr. Trades Council, 485 U.S. 568, 575 (1988) ("[W]here an otherwise
acceptable construction of a statute would raise serious constitutional problems, the
Court will construe the statute to avoid such problems unless such construction is plainly
contrary to the intent of Congress."); see also Consolidation Coal Co. v. United States, 528
F.3d 1344 (Fed. Cir. 2008) ("Even if we were to assume that the statute is ambiguous as to
the meaning of 'coal produced,' the government's construction must still prevail as it is the
only reasonable construction which preserves the constitutionality of the statute."); Agape
Church, Inc. v. FCC& United States, 738 F.3d 397, 413 (D.C. Cir. 2013) (Kavanaugh, J.,
concurring) ("[T]he FCC also invoked the principle of constitutional avoidance to support
its result here. In my view, the Commission was right to perceive a serious First
Amendment problem with the Viewability Rule."). Here, the Endangerment Finding asserted
overbroad authority and if the adverse commenters' interpretation is correct, there is a
constitutional problem that must be confronted. See, e.g., Ga. v. President of the United
States, 46 F.4th 1283 (11th Cir. 2022) (Anderson, J., concurring in part and dissenting in
part) ("the major questions doctrine is essentially a clear statement rule) (citing West
Virginia, 142 S. Ct. at 2616 (Gorsuch, J., concurring)); Heating v. EPA, 71 F.4th 59, 67 (D.C.
Cir. 2023) ("Whereas the major-questions doctrine has a constitutional basis -
safeguarding the 'separation of powers' by ensuring that agencies do not use statutory
ambiguities to make decisions vested in our elected representatives - the [rule of
interpretation that Congress does not alter the fundamental details of a regulatory scheme
in vague terms or ancillary provisions] rests on a more modest intuition about how we use
language.").
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The EPA further disagrees with the commenters that asserted a potential, rather than an
actual, nondelegation problem, would not warrant invoking the canon of constitutional
avoidance. Case law demonstrates that is precisely when constitutional avoidance is
appropriate. See Crowell v. Benson, 285 U.S. 22, 62 (1932) ("When the validity of an act of
the Congress is drawn in question, and even if a serious doubt of constitutionality is raised,
it is a cardinal principle that this Court will first ascertain whether a construction of the
statute is fairly possible by which the question may be avoided."); N.M. Cattle Growers'
Ass'n v. U.S. Fish & Wildlife Serv., 148 F.4th 755, 767 (D.C. Cir. 2025) ("[constitutional
avoidance] is a canon of statutory construction that comes into play only when, after the
application of ordinary textual analysis, the statute is found to be susceptible of more than
one construction") (internal citations and quotes omitted). To the extent the commenters
believe that section 202(a) provides an intelligible principle regarding regulation of GHGs
from motor vehicles in response to global climate change concerns, the authority in CAA
section 202(a)(1) is overbroad in that respect as discussed in the final action and this RTC.
The authority in CAA section 202(a) to "prescribe ... standards" for emissions by any class
or classes of new motor vehicles and engines is limited by the requirement that the
Administratorfind such emissions cause or contribute to air pollution that may reasonably
be anticipated to endanger public health and welfare. The best reading of the
statute recognized in this final action circumscribes this authority to air pollution that itself
endangers health or welfare through direct exposure. Underthe interpretation adopted in
the Endangerment Finding, however, our authority under CAA section 202(a) would have no
readily discernible limiting principle, particularly in combination with the authority asserted
to sever the analysis of endangerment and causation or contribution. Any "air pollutant"
emitted by vehicles or engines at more than de minimis volumes would trigger our authority
and obligation to prescribe standards so long as emission of the "air pollutant" from any
and all sources globally contributes to "air pollution" that, in turn, can be said to have any
causal relationship to adverse impacts on public health and welfare, broadly defined.
Additionally, the EPA disagrees with the commenters' suggestion that any hypothetical
pollutant that the EPA would seek to regulate would still need to be a reasonable exercise
of the agency's authority, subject to judicial review, as a backstop for nondelegation
concerns. The nondelegation doctrine serves to ensure that Congress doesn't
unconstitutionally delegate its authority to the Executive Branch; an agency may still
comply with the necessary process under the CAA and APA but abiding by the statutory
process cannot save the statute.
Section 202(a)(1) provides an intelligible principle to guide the EPA's discretion in setting
standards for air pollutants, excluding GHGs. The statute authorizes the EPA to prescribe
emission standards for air pollutants which, in his judgment, cause or contribute to air
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pollution which may reasonably be anticipated to endanger public health or welfare.
Congress provided guidance as to almost every other pollutant regulated under CAA
section 202(a)(1) by adding provisions elsewhere in CAA section 202 related to criteria
pollutants and air toxics. Some of those provisions are independent authorities, while
others layer on top of CAA section 202(a)(1). See, e.g., NRDC v. EPA, 655 F.2d 318, 322 (D.C.
Cir. 1981) ("Section 202(a)(1) of the [Clean Air] Act confers on the EPA Administrator the
general power to prescribe by regulation 'standards applicable to the emission of any air
pollutant from any class or classes of new motor vehicles or new motor vehicle engines,
which in his judgment cause, or contribute to, air pollution which may reasonably be
anticipated to endanger public health or welfare.' These provisions are supplemented and
qualified by various specific provisions relating to particular classes of vehicles or
pollutants. E.g., Act §§ 202(a)(3)(A)(i), 202(a)(3)(F), 202(b)(6)(A)."). When properly
interpreted, the statute does not raise constitutional concerns.
2.2 Futility of Eliminating GHG Emissions from All Motor Vehicles
2.2.1 Significance of the material impact of emission standards on public
health or welfare when making an Endangerment finding
EPA Summary of Comments
Commenters allege that futility as a basis not to prescribe GHG standards is incompatible
with the statutory text of CAA section 202(a)(1). They say that the text of section 202(a)(1)
does not require that standards achieve some "measurable" impact on the harms caused
by the air pollution, but asks whether vehicle emissions "cause or contribute" to air
pollution to trigger regulation. They say that the EPA assigns itself the role of determining
when a regulatory control program is appropriate and reasonable. Commenters claim
further that Congress decided this threshold question in section 202(a)(1), decidingthat
standards should be set if vehicle emissions contribute to air pollution and the air pollution
endangers.
Commenters contend that the futility rationale is inconsistent with binding precedent. They
argue that Massachusetts underscored that the EPA must ground action under 202(a)(1) in
a "contribution-and-endangerment" inquiry and cannot refuse to act based on policy
skepticism about incremental steps. They say the futility argument introduces extra
statutory factors into the inquiry.
They note the court in Massachusetts also rejected an argument about a measurability
threshold, stating it "rests on the erroneous assumption that a small incremental step,
because it is incremental, can never be attacked in a federal judicial forum. Yet accepting
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that premise would doom most challenges to regulatory action. Agencies, like legislatures,
do not generally resolve massive problems in one fell regulatory swoop." Further, they note
the Court recognized that a "reduction in domestic emissions would slow the pace of
global emission increases, no matter what happens elsewhere."
Commenters note that the D.C. Circuit rejected the argument that the EPA is required to
show that regulations "meaningfully mitigate the alleged endangerment" in Coalition for
Responsible Regulation. They note that the D.C. Circuit in Catawba County and Bluewater
Network considered the word "contribute" in the context of the CAA and rejected
arguments that it required any level of "significance." They say that whether the elimination
of GHGs from one kind of source would have a meaningful impact on the problem is not
relevant to the contribution analysis.
Commenters in support of the proposed action also note that regulations based upon even
the most optimistic assumptions yield de minimis and "truly trivial" impacts on GHG
emissions reductions and increased human welfare and are thus arbitrary capricious and
unlawful.
Commenters in support also noted the lack of CAA authority to regulate attenuated
"unquantifiable climate impacts."
EPA Response
The EPA recognizes that CAA section 202(a)(1) authorizes preventative regulation that need
not fully ameliorate the identified harms, but the agency disagrees with commenters that
argue futility is not material in applying CAA section 202(a)(1). In discussing the statute's
preventative nature, the EPA and reviewing courts consistently understood that regulation
must be capable of having at least a material impact on the identified danger. In enacting
and amending CAA section 202(a)(1), Congress legislated against background legal
principles. These include principles of causation and proximate cause. See, e.g., Bank of
Am. Corp. v. City of Miami, 581 U.S. 189, 201 (2017); Lexmark Int'l, Inc. v. Static Control
Components, Inc., 572 U.S. 118,132 (2014); Univ. of Tex. Sw. Med. Ctr. v. Nassar, 570 U.S.
338, 347 (2013); City of Oakland v. Wells Fargo & Co., 14 F.4th 1030 (9th Cir. 2021) (en
banc).
In addition, courts have long recognized the "background" legal principle "against which all
enactments are adopted" that general language does not encompass de minimis concerns
- de minimis non curat lex ("the law cares not for trifles"). Wisconsin Dep't of Rev. v.
William WrigleyJr., Co., 505 U.S. 214, 231 (1992); see UARG, 573 U.S. at 309 n.1. Unless the
statute provides otherwise, agencies have implied authority to exempt de minimis
concerns "when the burdens of regulation yield a gain of trivial or no value." Ala. Power Co.
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v. Costle, 636 F.2d 323, 360-61 (D.C. Cir. 1979). Courts have recognized the applicability of
this principle to the CAA in other contexts. Id.; Ethyl Corp. v. EPA, 541 F.2d 1, 29-32 (D.C.
Cir. 1976) (en banc). The EPA recognized in the Endangerment Finding that CAA section
202(a) incorporates de minimis principles, stating that the contribution of motor vehicle
and engine GHG emissions to the "air pollution" must be more than trivial. See 74 FR
66506, 66509, 66542-43. In Wisconsin Dep't of Revenue, the Supreme Court recognized
that it would be "especially unreasonable" to not apply the de minimis principle where a
statute operates in a "stark, all-or-nothing fashion," as commenters suggest that CAA
section 202(a)(1) operates.
An additional background legal principle against which we must interpret section 202(a)(1)
is the presumption against ineffectiveness, the idea that Congress presumably does not
enact useless laws, a corollary of which would be that Congress does not enact legislation
that requires useless regulatory efforts, and it is not appropriate for an agency to presume
Congress would enact legislation requiring the agency to perform ineffective regulatory
exercises, barring unmistakably clear direction or express authorization to the contrary.
See Jackson v. S.S. Archimedes, 275 U.S. 463,468 (1928) ("a purpose so wholly futile is not
to be attributed to Congress"); Garland v. Cargill, 602 U.S. 406, 427 (2024) (citing United
States v. Castleman, 572 U.S. 157,178 (2014) (Scalia, J., concurring in part and concurring
in judgment)). This principle, like the de minimis principle, is presumed to be implied in all
statutory schemes. There is no indication in the statutory text, nor any contention by
commenters, that this principle should not apply to section 202(a)(1).
These background principles inform our interpretation of CAA section 202(a)(1) by
suggesting that the provision does not encompass the attenuated chain of causation
required to invoke the authority to regulate GHG emissions to address global climate
change concerns where regulations cannot have more than a trivial impact on the
identified dangers to health and welfare. The inability of new motor vehicle and engine
GHG emission standards to have any material impact on the health and welfare impacts
associated with global climate change suggests that it is unreasonable to read the statute
in a way that permits regulation in response to global climate change concerns. This
concern is de minimis because the regulation of GHGs would have no material impact on
the danger, and furthermore any GHG standards established would be nothing more than
an "ineffective regulatory exercise," which we must presume Congress would not have
intended.
An examination of the text of CAA section 202(a)(1) demonstrates that the provision is not
"extraordinarily rigid" such that these background principles would not apply. Regulation
under section 202(a)(1) is first a foremost predicated on the Administrator's "judgment."
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This suggests that the Administrator should not apply the statute in a rigid or mechanical
way, but rather use reasonable judgment to determine whether the statutory standard for
regulation is met. The Administrator's judgment extends to making determinations
regarding causation and contribution, as well as what may "reasonably be anticipated to
endanger," which itself indicates that the Administrator has some discretion in assessing
what he or she considers "reasonable" before making an Endangerment Finding underthe
statute. Therefore, it is clear that section 202(a)(1) is far from a binary "on/off" switch under
which vehicle emissions either contribute or do not, as commenters allege, but rather
implicit in the discretion given to the Administrator to exercise reasonable judgment, there
is ample room for the de minimis and futility principles to operate.
An additional statutory point lends additional support to the understanding that regulatory
futility underlies the statutory scheme in CAA section 202(a)(1). As discussed in the final
action and section 2.1.1.3 of this RTC, the best reading of section 202(a)(1) is to require at
least some nexus between "contribution" and "endangerment" to satisfy the standard for
regulation. Regulatory futility naturally becomes part of this analysis where the EPA must
consider contribution alongside the alleged dangers associated with the air pollution to
which motorvehicle emissions contributes. Put more plainly, if the complete elimination of
a pollutant from section 202(a) sources would have no material impact on public health or
welfare, it cannot be said that such sources truly "contribute" to the pollution that causes
those impacts, at least in more than a de minimis manner. By expressly relying on statutory
silence to sever the findings from the standards, the Endangerment Finding was also able
to sidestep the futility analysis and achieve its preferred regulatory outcome, but in the
process stretched the text of section 202(a)(1) beyond its breaking point - particularly in
the wake of Loper Bright.
Further, the futility determination reached in this final action is different in kind from the
policy arguments previously addressed in Massachusetts and Coalition for Responsible
Regulation, which focused on the cost-benefit balance of potential regulatory responses
and general concerns about the most efficient way to regulate in response to global
climate change concerns. The problem of futility here is not a policy concern, as
commenters allege, but rather a matter of statutory interpretation, based in the two
background principles identified above. Based on these principles we conclude that CAA
section 202(a)(1) requires that emission standards be capable of having a material impact
on the identified danger for the Administrator to conclude that the emissions "contribute"
to air pollution that may "reasonably be anticipated" to endanger public health and
welfare. If controlling or eliminating the emissions would not materially impact the
identified danger, the emissions do not "contribute" to the air pollution. And because the
emitted "air pollutant" and the "air pollution" are defined in this context as the "six well-
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mixed GHGs," the air pollution cannot "reasonably be anticipated" as endangering health
or welfare in the CAA section 202(a) context if controlling or eliminating all vehicle and
engine emissions would have no impact on the public health and welfare impacts of global
climate change. Put another way, the inability of GHG emission standards to have any
material impact demonstrates that GHG emissions from new vehicles and engines do not
contribute to dangerous air pollution that endangers public health or welfare. That
determination is relevant to the findings required by CAA section 202(a)(1).
As to the specific statements made by the Supreme Court in Massachusetts that
commenters claim foreclose interpreting CAA section 202(a)(1) in this way, an examination
of each discussion in its relevant context reveals that neither is speaking to the proper
interpretation of section 202(a)(1) or rejecting the interpretation put forward by the EPA
here regarding the regulation of de minimis concerns and futile regulatory exercises. First,
where commenters point to the Supreme Court's statement in Massachusetts purporting
to reject a measurability threshold in section 202(a)(1), it is crucial to recognize that the
Court's discussion was in the standing section of the Supreme Court's opinion.
Massachusetts, 549 U.S. at 524-25. When assessing standing, courts presume the merits
of the underlying arguments to determine whether the injury as alleged is traceable to the
challenged action and redressable. The Court accepted for the purpose of the standing
analysis the allegation that any amount of emissions contributes to global climate change
and therefore in turn that any amount of emission reduction reduces global climate
change. Consistent with the Court's ultimate remand to the EPA, we are concluding here
that this allegation is not correct - even eliminating all domestic motor vehicle emissions
would have no material benefit for the ultimate object of the statutory provision, namely
the public health and welfare concerns associated with global climate change.
The EPA also disagrees with commenters that argue Catawba County and Bluewater
Network foreclose our interpretation of section 202(a)(1) to not permit futile regulations.
These cases are discussed more fully in section 2.1.1.3.2 of this RTC ("Threshold for Cause
or Contribution"), and that discussion is fully applicable here. To briefly reiterate, most
crucially for the purposes of this discussion, neither of these cases consider norforeclose
the application of the de minimis principle implicit in section 202(a)(1), which we must
presume applies in all cases absent indication to the contrary.
Additionally, the D.C. Circuit's statement in Coalition regarding "meaningful mitigation of
alleged endangerment" was in the context of rejecting petitioners' challenge that the
Tailpipe Rule was arbitrary and capricious because the EPA failed "to show that the
proposed standards would meaningfully mitigate the alleged endangerment." 684 F.3d at
127. The court emphasized that what was at issue was ultimately a record determination,
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and the court rejected the argument because it determined that the record was "fulsome"
and sufficient to support the EPA's findings that vehicle emissions significantly contribute
to domestic GHG emissions and that the emissions standards would result in meaningful
mitigation of those emissions. Id. at 128.
Here, the EPA is not contesting the emissions reduction potential of GHG standards.
Rather, our position is that the very regulation of GHGs in response to global climate
change concerns is not permissible under CAA section 202(a)(1) because such an exercise
is futile. The EPA maintains that the Agency was previously concerned with the wrong
impacts - emission reduction potential is irrelevant under the statutory scheme, which
requires regulation upon a findingthat air pollution endangers public health or welfare.
Where standards established under the provision would befutilein addressing those
dangers, we must assume the statute does not permit regulation regardless of any
decrease in raw emissions. The Endangerment Finding itself did not seriously engage with
the impacts of regulating GHGs under section 202(a)(1), instead sidesteppingthe issue by
severing both findings from standards and the contribution and endangerment analyses.
To the extent that the EPA previously conducted any impact analysis analogous to the
modeling that we have done here regarding sea level rise and temperature increase, this
was done in the context of assessing the impacts of the GHG standards in previous light-,
medium-, and heavy-duty GHG rules and the results are largely in line with the modeling
that the EPA conducted for this rule. For the analysis of the impacts of the 2010 light-duty
vehicle GHG rule, the EPA found atmospheric C02 concentration to be reduced by
approximately 2.7 to 3.1 parts per million (ppm), global mean temperature was projected to
be reduced by approximately 0.006-0.015°C by 2100, and global mean sea level rise was
projected to be reduced by approximately 0.06-0.14 cm by 2100. The levels of the
projected reductions due to the light-duty GHG rule are in line with, but less than, the
overall contribution of the LD vehicle sector modelled by the EPA in 2025. The EPA
assessed the impact of the HD GHG Phase 2 emission standards on the global climate in
2016 based on the projected change in atmospheric C02 concentration, global mean
surface temperature, sea level rise, and ocean pH in 2100 compared to a baseline without
the rule. The reduction in global atmospheric C02 concentration in 2100 was projected to
be between 1.2 to 1.3 ppmv. The reduction of the global mean surface temperature was
projected to be 0.0027 to 0.0065 degrees C in 2100. The reduction in sea level rise was
projected to be 0.026 to 0.058 cm in 2100. The levels of the projected reductions due to the
HD GHG Phase 2 rule are in line with, but less than, the overall contribution of the HD
vehicle sector modelled by the EPA in 2025.
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While the modeling that the EPA did for this rule regarding these impacts is in line with the
EPA's prior analyses - finding exceedingly small impacts on sea level rise and temperature -
the EPA previously approached the question from a different analytical framework. The
rules that the previous modeling was associated with accepted the Endangerment Finding
as a baseline, and thus had no occasion to assess whether such impacts might have
informed making such a finding at all.
Since the Endangerment Finding, the EPA has used social cost of carbon (SCC) metrics to
work around the problem of regulatory futility associated with regulating GHGs under
section 202(a)(1). Again, as the Endangerment Finding itself did not even attempt to assess
impacts, what we are doing here is distinct from any prior analysis in that it asks whether
there is any material impact that would satisfy the statutory standard for regulation. In fact,
the same FaIR model and BRICK model used here to model sea level rise and global
temperature are used as inputs to estimate global mean surface temperature and sea level
rise when calculating SCC. However, after ascertaining those impacts, the SCC analysis
would translate those climate impacts into monetary figures purporting to represent public
health and welfare impacts. However, the EPA now recognizes there are significant
uncertainties associated with performing monetized impacts quantifications, and such
quantifications can be readily manipulated to support a preferred regulatory outcome. The
EPA's recognition of the problems and inherent biases in SCC calculations aligns with
Executive Order (E.O.) 14154, "Unleashing American Energy," which withdrew earlier
guidance on calculatingthe social cost of carbon, as well as the subsequent memorandum
from the Office of Management and Budget (OMB), M-25-27, which directed agencies not
to quantify or monetize the impacts of GHG emissions, except to the extent required by
law, "because the uncertainties in performing monetized impacts quantifications are too
great."
Finally, insofar as commenters or others have concerns that the futility problems identified
by the EPA in this case would logically extend to other pollutants currently regulated under
CAA section 202(a)(1), this is simply not true. The futility problem arises from the unique
nature of global climate change and the inherent mismatch between climate change
concerns and section 202(a)(1). Unlike GHGs, other pollutants regulated under section
202(a)(1) are associated with "local and regional" air pollution problems. Therefore, even if
emission standards do not have a material impact on the pollution problem on a global, or
even national, scale, it cannot be said that the standards are futile where there are local
and regional benefits related to public health and welfare. Here, because the
Endangerment Finding was concerned with the health and welfare impacts associated with
global climate change, which the Endangerment Finding itself acknowledged would require
global action to meaningfully address, we cannot say that there are any material benefits of
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this nature. This again underscores that section 202(a)(1) was never designed or intended
for the purpose of addressing GHGs and global climate change.
2.2.2 Contribution determination and de minimis emissions
EPA Summary of Comments
Commenters reject the proposal's argument that the Endangerment Finding based its
contribution determination on a determination that motor vehicles contributed to GHG air
pollution because they emit GHGs above de minimis levels. Rather, they contend that the
Endangerment Finding found that "contribution from section 202(a) source categories is
significant because their emissions are larger than the great majority of emitting countries
and constitute one of the largest parts of the US emissions inventory."
EPA Response
These commenters misunderstand the nature of the errors that the EPA has identified in
the Endangerment Finding regarding futility. The EPA does not dispute the contribution
finding that was made in the Endangerment Finding. What we do take issue with, however,
is how the Endangerment Finding evaded the futility problem by stating that section
202(a)(1) only required a finding of contribution above de minimis levels but maintaining
that whether regulation would have any impact on health or welfare was irrelevant by
severing the contribution and endangerment findings as well as severing the findings from
the responsive regulation. Because of this, while the EPA recognized in the Endangerment
Finding that CAA section 202(a) incorporates de minimis principles, stating that the
contribution of motor vehicle and engine GHG emissions to the "air pollution" must be
more than trivial, we avoided consideration of this limitation in the remainder of the
analysis. See 74 FR 66506, 66509, 66542-43. We asserted that requiring the Agency to
show that control measures "would prevent at least a substantial part of the danger" would
"be an unworkable interpretation, calling for the EPA to project out the result of perhaps
not one, but even several, future rulemakings stretching over perhaps a decade or
decades." 74 FR 66507-08. After the Endangerment Finding, we focused on estimates of
GHG emission reductions and, in RIAs not relied upon to justify the standards, attempts to
monetize such reductions using the SCC methodology. See, e.g., 89 FR 29440, 29675 (Apr.
22, 2024) (HD GHG emission standards); 75 FR 25324 (May 7, 2010) (Tailpipe Rule). That
was not consistent with the best reading of the statute, which provides that the proper
focus is not on the emissions themselves, but on the possible dangers to health or welfare.
Recognizing that section 202(a)(1) must be read against the background principles
discussed above, it was impermissible forthe EPA to dismiss any discussion of material
impact as irrelevant. Again, the inquiry is not simply (as commenters allege) what level of
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contribution is required to determine that "contribution" is satisfied, but rather whether
regulating GHGs from motor vehicles would be addressing a de minimis concern and
constitute a futile regulatory exercise because of the inability of such regulations to
materially address the public health and welfare concerns associated with global climate
change.
2.2.3 Application of the futility rationale to other pollutants, sources, and
global GHG emissions
EPA Summary of Comments
Commenters assert that interpreting CAA section 202(a)(1) to require the meaningful
reduction of pollution in order to regulate at all is at odds with how the EPA approaches
contributions to large national and global pollution problems elsewhere in the CAA. They
say that the EPA does not attempt to square this position with prior conclusions that
smaller contributions still "significantly contribute" to dangerous pollution and that their
reductions reduce endangerment. Commenters say this includes the regulation of GHGs
from aircrafts under CAA section 231 which had no associated GHG emission reductions,
as well as for nonroad engines under 213. Rather than dismissing such standards as
"futile," the EPA concluded the standards would prevent backsliding, protect global
competitiveness and carry substantial benefits for future international cooperation on
worldwide emission reductions. They note that the proposal does not mention these
benefits, despite their relevance. Commenters also say that the CAA specifically requires
regulation of stratospheric ozone depleting substances, despite no single country
being responsible for the majority of such emissions and regulation requiring global
cooperation.
Commenters also state that under the EPA's proposed standard, where a source category
could only be regulated if its pollution is single-handedly responsible forthe harm, many
conventional pollutants likely could not be regulated because controlling any individual
source category would not meaningfully address the aggregate health problem. They say
that considering section 202(a), this interpretation if applied to the regulation of criteria
pollutants would threaten the existence of the entire program.
Commenters also assert that the EPA fails to confront the outcome of its position if other
countries were to adopt it. Commenters argue that under the proposal's logic, no country
would mitigate vehicle GHG emissions since the contribution of vehicles from any
particular country is too small a portion of the whole problem to have a meaningful
impact.
EPA Response
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Commenters here misstate the EPA's argument in regard to "meaningful" and seem to
generally misunderstand this part of the discussion. To clarify, in this part of the discussion
the EPA is generally stating that regulation cannot be futile, meaning regulation needs to
have at least a non de-minimis impact on the identified dangers. This discussion of futility
is tied to section 202(a)(1) and what the EPA considers the best reading of the specific text
in that provision, including that the emission must cause or contribute to the danger posed
by the air pollution to a sufficient extent to satisfy the standard for regulation. The policy
implications of the futility argument in other contexts is not (and cannot be) something the
agency considers in this rulemaking.
Next, to be clear, this action focuses squarely on the specific text in section 202(a)(1) so
the comments on how the EPA approaches regulating pollutants in other parts of the CAA
are outside the scope of this action. However, for commenters' benefit, we will explain this
in some more detail as it relates to the various provisions raised. As to commenters
statements related to aircraft and nonroad engine regulations, commenters are comparing
two very different programs that fall under different statutory provisions and are informed
by different contexts, so the two cannot be equated in this way. For example, CAA section
231 rulemakings have to contend with international treaty obligations and consider global
issues like exports, which is an entirely different set of factors and analysis than exists
under CAA section 202(a)(1). Therefore, these comments are not relevant and are out of
scope.
Commenters note that the CAA specifically requires regulation of stratospheric ozone
depleting substances, despite no single country being responsible for the majority of such
emissions and regulation requiring global cooperation. While this provision is out of scope,
the EPA agrees that this type of provision is precisely what Congress can choose to write
into the statute in circumstances where it wants to legislate on an issue of global concern.
When Congress wanted to address depletion of the ozone layer, it enacted an entirely new
title with different authorities that speak expressly to that issue and its relation to global
concerns. When presented with the option to do something similarthrough legislation for
GHGs in 2007-2009, Congress did not do so. Because Congress chose not to act on this
topic does not mean the EPA can stretch its authority under CAA section 202(a)(1), that is
not within the discretion of an executive agency. CAA section 202(a)(1) simply does not
authorize the EPA to prescribe standards for GHG emissions based on global climate
change concerns. Finally, commenters' assertions related to criteria pollutants are off base
and not at issue, as this rulemaking is specific to GHGs. Also, because other pollutants
regulated under section 202(a)(1) "cause or contribute" to local or regional air pollution
problems, setting standards will have an impact on the local or regional level. Therefore, it
cannot be said that such standards are futile even if they do not meaningfully impact the
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pollutant's total concentration globally. Conversely, the Endangerment Finding directly ties
GHG standards to global climate change - a problem that they are futile in addressing. All
of this to say, the pollutants clearly regulated under CAA section 202(a)(1) do not involve
the same unique problems and unique approach as occurs in the Endangerment Finding.
In regard to commenters' concern that if other countries adopt the EPA's approach to
futility, no country would mitigate vehicle emissions, the EPA acknowledges commenters
concern and again asserts that if true, this is a question for Congress to address, and
Congress did not do so when it enacted CAA section 202(a)(1) in 1965. Additionally, the
CAA includes only a few provisions addressing international emissions and none of those
apply here. The one provision that authorizes the EPA to require States to restrict emissions
through state implementation plans that impact foreign countries require separate
findings, and that the other country have reciprocal protections in place.
Additionally, there are flaws in commenters' logic. First of all, finding futility as to vehicle
emissions is not the same thing as finding futility for all U.S. emissions, and again
demonstrates the blurring of lines that has occurred from the flaws in the 2009
Endangerment Finding analysis. Secondly, the EPA is finding futility only with respect to the
tools that Congress provided in CAA section 202(a)(1). Just because the tool provided does
not fit the problem, does not mean that the United States or the global community is
powerless to address the problem, if those parties decide it is a problem. As discussed in
the context of stratospheric ozone, Congress can and has previously provided additional
authorities to address global problems where it sees fit. Congress and the Executive have
also engaged internationally in treaty negotiations where they see fit.
The potential inability of Congress or the global community to come to agreement on
whether and howto address a potential global problem does not justify interpreting CAA
section 202(a)(1), a general backstop provision dating back to 1965, to confer such
authority. As the Supreme Court noted in West Virginia, "Capping carbon dioxide emissions
at a level that will force a nationwide transition away from the use of coal to generate
electricity may be a sensible "solution to the crisis of the day." New York v. United States,
505 U. S. 144, 187, 112S. Ct. 2408, 120 L. Ed. 2d 120(1992). But it is not plausible that
Congress gave the EPA the authority to adopt on its own such a regulatory scheme in
Section 111 (d). A decision of such magnitude and consequence rests with Congress itself,
or an agency acting pursuant to a clear delegation from that representative body." West
Virginia v. EPA, 597 U.S. 697, 735 (2022). Please see the final action preamble and RTC
sections on the Major Questions Doctrine for a comprehensive discussion on this topic.
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2.2.4 Factual support for futility of the GHG motorvehicle emission standards
EPA Summary of Comments
Commenters allege that even taken on its own terms, the futility argument is contrary to
overwhelming evidence, such that the EPA cannot reasonably determine that regulation of
GHGs would be futile. They suggest that overwhelming scientific evidence shows that US
on-road vehicles make a meaningful impact on the identified danger. They comment that
the U.S. is the second largest emitter of GHGs after China and transportation is the largest
source of US GHG emissions, the majority of which is from light duty vehicles. They
comment that US new motor vehicles comprise 1.8% of global GHG emissions, which is
more than all but eight countries' total emissions.
Additionally, commenters say that the contribution of US vehicles to national emissions is
most relevant to the EPA's authority to regulate under the CAAand that the EPA is
effectively proposing that it should ignore the largest source of GHG emissions within U.S.
borders. Furthermore, they say GHG regulations of the U.S. vehicle sector have significant
impacts on global vehicle manufacturing.
Commenters argue that the EPA's new position contradicts the EPA's previous findings
that regulating GHGs has resulted in measurable decreases in GHG emissions and
quantifiable improvements in public health (including in fuel efficiency regulations). They
argue that the proposal confuses statistical variance in global warming trends with the
concept of a quantity of GHG whose emission will make no difference. They say that in the
context of our present-day circumstance, where humanity's use of fossil fuels has caused
us already substantially to overshoot the safe level of atmospheric C02, there is really no
de minimis additional contribution from a major source unless one is considering a
quantity that is truly undetectable by any pertinent instrument or sensor.
Some commenters also assert that the empirical foundations of the EPA's previous
findings, the models relied upon, and based GHG scenarios have all failed to materialize
and are empirically false based upon "updated evidence [which] overwhelmingly
undermines every core justification" in the Endangerment Finding.
EPA Response
The EPA first would like to note that the proposed climate science basis is not being
finalized, and therefore many of the comments made are out of scope and no longer
relevant. The EPA also reminds commenters that the futility argument is not about the
amount of GHG emissions that originate from section 202(a) sources, but about the impact
that regulating these sources would have on the harms to public health and welfare caused
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by global climate change. Whether or not the U.S. is the second largest emitter of GHGs
after China, does not mean that regulation is not futile if regulation will have a de minimis
impact on the danger identified. Whether or not transportation is the largest source of US
GHG emissions, does not mean that regulation is not futile if regulation will have de
minimis impacts on the danger identified. Whether or not US new motor vehicles comprise
1.8% of global GHG emissions, does not mean that regulation is not futile if the regulation
will have a de minimis impact on the danger identified. The EPA reminds commenters of
what is discussed throughout the preamble and RTC for this rule: the potential inability of
Congress or the global community to come to agreement on whether and how to address a
potential global problem does not justify interpreting CAA section 202(a)(1), a general
backstop provision dating back to 1965, to confer such authority. Commenters' data
points, if true, may or may not point to a global problem, but the existence of a problem
does not magically confer new authority into CAA section 202(a)(1) that Congress did not
intend.
That said, to commenters' points that relate to futility, commenters misunderstand some
key realities and do not explain the necessary context around many statements. First, while
the EPA has previously found that regulating GHGs has resulted in measurable decreases
in GHG emissions on new vehicles, even after several rounds of GHG regulations, we see at
the global level, the most recent available data show that GHG emissions are continuing to
increase.29 In 2022, energy-related emissions grew to the highest level ever of 41.3 G
tonnes C02 equivalent. These GHG emissions are primarily from C02 combustion (89
percent) with the remainderfrom methane emissions from combustion and oil and gas
extraction.30 Second, while the EPA found that regulating GHGs has resulted in quantifiable
improvements in public health by usingthe social cost of carbon for monetizing the
impacts of GHG emission reductions, the Executive Order (E.O.) 14154, "Unleashing
American Energy" withdrew earlier guidance on calculating the social cost of carbon.31 In
response, the Office of Management and Budget (OMB) issued Memorandum M-25-27
providing current guidance on the consideration of GHGs in regulatory decision-making.32
That Memorandum directed agencies not to quantify or monetize the impacts of GHG
emissions, except to the extent required by law, "because the uncertainties in performing
291EA (2023), C02 Emissions in 2022. https://vwvw.iea.org/reports/co2-emissions-in-2022
30 Energy-related emissions include C02, CH4, N20 emissions from fuel combustion and fugitive emissions,
across the following sectors: Electricity & Heat production, Industry & Manufacturing, Transport, and
Buildings.
31 90 FR 8353 (Jan. 29, 2025) "UnleashingAmerican Energy."
32 https://www.whitehouse.gov/wp-content/uploads/2025/Q2/M-25-27-Guidance-lmplementing-Section-6-
of-Executive-Qrder-14154-Entitled-Unleashing-American-Energy.pdf. and posted in the docket for this rule.
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monetized impacts quantifications are too great." The EPA agrees with Memorandum M-25-
27 that it is inappropriate to utilize the SCC due to the significant uncertainties.
The proposal does not include confusion about statistical variance in global warming
trends, and that comment is generally out of scope due to the fact that the EPA is not
finalizingthe climate science basis. Additionally, the argument that because global C02
emissions have already passed "safe" levels, there is no de minimis additional contribution
from a major source unless it is a quantity that is undetectable by any pertinent instrument
or sensor, is again a flawed argument for reasons already discussed in this section and
others. While commenters may or may not identify a global problem to be addressed, that
does not mean Congress gave authority to the EPA in CAA section 202(a)(1). And as noted
in other sections, the EPA and reviewing courts consistently understand that regulation
must be capable of having at least a material impact on the identified danger. Congress
does not require useless regulatory efforts, and it is not appropriate for an agency to
presume Congress would enact legislation requiring the agency to perform ineffective
regulatory exercises, barring unmistakably clear direction or express authorization to the
contrary. See Jackson v. S.S. Archimedes, 275 U.S. 463, 468 (1928).
And here, the total elimination of GHGs from vehicles would barely impact global
emissions (as supported by commenters' data points above), so any finding that regulation
of GHGs from new motor vehicles would have any impact on public health and welfare
associated with climate change simply cannot be true. The EPA cannot change the
meaning of section 202(a)(1) so that it will support regulation of a pollutant based on the
share of U.S. emissions of that pollutant where a contribution/endangerment finding
cannot be made because regulation would be futile.
2.2.5 Independent basis for repealing GHG emission standards
EPA Summary of Comments
Commenters allege that to the extent the EPA proposes that "futility" is a valid basis not to
prescribe GHG standards even after a finding of endangerment and contribution, that
position is incompatible with the statutory text. They also say that as long as the
Endangerment Finding remains in place, under section 202(a) of the CAA, regulation is
mandated and the EPA has no discretion to decline to regulate and has no delegated power
to apply policy or politics to avoid what Congress mandated.
EPA Response
As explained in the final action preamble, the EPA is finalizingthe futility rationale as a
standalone basis for repealing the GHG emission standards. Even if the CAA section 202(a)
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authorized the Endangerment Finding as a standalone decision, it would be unreasonable
and impermissible to retain a regulatory program that imposes immense costs while
providing no material value in furtherance of a legitimate statutory objective. This
alternative basis turns on the statutory language in CAA section 202(a) more generally,
including the cost consideration requirements of CAA section 202(a)(2).
As the Supreme Court explained in Michigan, agencies are bound to consider cost unless
the statute expressly provides otherwise. See Michigan v. EPA, 576 U.S. 743, 752 (2015)
("One would not say that it is even rational, never mind 'appropriate,' to impose billions of
dollars in economic costs in return for a few dollars in health or environmental benefits.").
Here, where the costs of regulation are certain and immense but the health and welfare
value of regulation are uncertain and de minimis, it is futile and thus unreasonable to
maintain the GHG emissions program. However, as explained in RTC sections 2.1 and 2.2,
while the EPA did consider costs, the EPA does not base its decision here upon cost, but on
the primary rationales laid out in the preamble.
2.2.6 Modeling of Global Climate Change Impacts Attributed to U.S. Motor
Vehicles
EPA Summary of Comments
Several commenters cited work from a June 2025 publication from the Texas Public Policy
Foundation which modeled the impacts of eliminatingthe U.S. power sector C02
emissions using the Model for the Assessment of Greenhouse Gas Induced Climate
Change (MAGICC) model, as well as the impact of eliminating all U.S. C02 emissions
(referencing "The Materiality of U.S. C02 Emissions on Global Climate Change," Brent
Bennet for TPPF, June 2025). These commenters stated that eliminating all U.S. power
sector C02 emissions by 2030 would reduce global C02 concentrations in 2050 by 3.4 parts
per million (ppm), or 0.7 percent, and reduce the mean global surface temperature in 2050
by 0.015 °C. The commenters stated that eliminating all U.S. C02 emissions by 2030
(including light-, medium-, and heavy-duty vehicles) would reduce global C02
concentrations in 2050 by 11.4 ppm, or 2.3 percent, and reduce the mean global surface
temperature in 2050 by 0.052 °C. One of the commenters stated the modeled temperature
increase impacts are not measurable in the global context as they fall within the
measurement error for global temperatures.
One commenter said that "under assumptions likely to exaggerate the future impacts of
those emissions, the EPA climate model predicts that net-zero U.S. emissions would
reduce year 2100 global temperatures by 0.137 °C. That effect would be either
undetectable or barely detectable depending on the structure of an applied statistical test,
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and in any event is trivial as a policy matter. The effect of a reduction in all vehicle
emissions or Clean Air Act (CAA) Section 202(a) vehicle emissions would be vastly smaller."
Further, this commenter stated "If we apply the EPA climate model (MAGICC 7) under an
assumed equilibrium climate sensitivity of 3°C, net-zero U.S. GHG emissions achieved by
2050 would reduce global temperatures by 0.137°C. (In a recent analysis, Lewis reports a
range for ECS of 1.55°C-3.2°C for a 5%-95% confidence interval.) Note that the standard
deviation of the surface temperature record is very likely to be between 0.08°C and 0.11°C.
Accordingly, the year 2100 temperature impact of U.S. net-zero GHG emissions would be
either undetectable or barely detectable depending on the structure of an applied
statistical test, and in any event is trivial as a policy matter. The 2009 Endangerment
Finding in Table 1 reports that 2005 CAA Section 202(a) GHG emissions were 23.5 percent
of all U.S. GHG emissions. If we apply a linearity assumption, net-zero emissions from CAA
Section 202(a) sources would yield a reduction in year 2100 global temperatures of
0.032°C, an outcome obviously not statistically significant and thus undetectable."
Several commenters cited modeling work by Benjamin Zycher, including one commenter
who stated "Because of foreign GHG emissions, moving the entire U.S. economy to 'net-
zero' emissions would have only a trivial effect on global average temperatures. Using the
MAGICC model [previously] employed by the EPA, see https://magicc.org/, expert
Benjamin Zycher demonstrated that 'Net-zero U.S. GHG emissions effective immediately
would yield a reduction in global temperatures of 0.173°C by2100.That effect would be
barely detectable given the standard deviation (about 0.11°C) of the surface temperature
record.' Left Holding the Bag: The Cost of Oil Dependence in a Low-Carbon World: Hearing
Before the S. Comm. on the Budget, 118th Cong. 1, 36 (Mar. 9, 2023) (statement of
Benjamin Zycher, Senior Fellow, Am. Enter. Inst.), https://tinyurl.com/4vsy7df6. So
eliminating U.S. carbon dioxide emissions will have almost no effect on temperatures, and
therefore no measurable effect on public health or welfare."
Citing modeling work from Benjamin Zycher "If the U.S. reduced C02 and other GHG
emissions to net zero effective immediately, rather than waiting until 2050, what does the
MAGICC model predict the effect on global temperatures would be in 2100? Virtually
nothing, 0.17 °C (0.31° F)."
Another comment stated "At the time of the Endangerment Finding, the EPA reported that
US carbon dioxide-equivalent emissions in 2005 totaled 7,109 million tons or 18 percent of
global annual emissions. If one assumes 3.0 °C climate sensitivity, then achieving NetZero
US emissions by 2050 would reduce global warming in 2100 by 0.137 °C. Assuming former
NASA scientist James Hansen's standard deviation estimate of 0.11 °C, 'the year 2100
temperature impact of U.S. net-zero GHG emissions would be either undetectable or
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barely detectable.' At the time, the EPA estimated that Section 202 vehicles accounted for
23.5 percent of total US GHG emissions. Thus under a simplifying assumption of linearity,
achieving NetZero for Section 202 US motor vehicles would reduce year 2100 global
temperatures by 0.032 °C, 'an outcome obviously not statistically significant and thus
undetectable.'"
Another commenter discussed work which appears to be based on work by Benjamin
Zycher, though without citation. This commenter stated "Moreover, even if every
Endangerment Finding projection had been correct, U.S. GHG reductions remain globally
trivial. EPA's own MAGICC model—using assumptions that exaggerate warming (RCP 8.5,
ECS = 4.5 °C)—shows that net-zero U.S. emissions through 2100 would avert only 0.137 °C
of warming. That effect is undetectable, immaterial, and irrelevant to human welfare.
Vehicle emission rules under Section 202(a) would yield reductions several magnitudes
smaller."
A commenter asserted that the EPA's own statement that the light- and medium-duty GHG
standards would result in 'an approximate 3 percent reduction in predicted warming
trends' concedes the agency's own belief that the GHG standards do in fact mitigate global
warming and that such impacts can be quantitatively assessed. They said that the EPA has
actually modeled the physical climate impacts of its prior GHG rules. The commenter said
that in the 2010 Light-Duty GHG Rule, the EPA applied a widely-used and peer-reviewed
model to estimate the physical climate effects of its regulations and identified "small, but
quantifiable, reductions in atmospheric C02 concentrations, projected global mean
surface temperature and sea level resulting from this action, across all climate
sensitivities. They say that as a result of the emission reductions from this action, the
atmospheric C02 concentration is projected to be reduced by an average of 2.9 parts per
million (ppm), the global mean temperature is projected to be reduced by approximately
0.006-0.015 °C by 2100, and global mean sea level rise is projected to be reduced by
approximately 0.06-0.14cm by 2100." The commenter said that the EPA also concluded
that "[tjhough the magnitude of the avoided climate change projected here is small, these
reductions would represent a reduction in the adverse risks associated with climate
change... across all climate sensitivities," and the resulting "differences in climate effects
(C02 concentration, temperature, sea-level rise, ocean pH)... yield results that are
repeatable and consistent within the modeling frameworks used."
A commenter stated that they had used the MAGICC model version 6 to quantify the
climate impact of eliminating all GHG emissions from motor vehicles. The commenter
found that, "even assuming a climate sensitivity of 5.0°C, the upper bound of estimated
climate sensitivities indicated by the UN IPCC, eliminating greenhouse gas emissions from
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motor vehicles would reduce global temperatures by less than 0.0305°C by 2050, and less
than 0.0644°C by 2100."
A commenter asserted that in section V of the proposal, the EPA claims that 'reducing GHG
emissions from such vehicles to zero would not measurably impact GHG concentrations in
the atmosphere or the rate of global climate change.' This is inaccurate." This commenter
also stated "After fragmenting estimates of national emissions multiple times, the EPA
estimates that eliminating emissions from United States light and medium duty vehicles
would reduce global GHG emissions by 1.8%. The commenter said that in 2024, the NOAA
Global Monitoring Laboratory determined a single-year increase in atmospheric C02
concentrations of 3.73 ppm, with an uncertainty of 0.09 ppm (Lan et al., 2025). 1.8% of this
increase corresponds to 0.067 ppm in a single year. The emissions reduction would
therefore be measurable in less than two years." This commenter also stated "Using the
IPCC's Absolute Global Temperature change Potential (AGTP) estimate of carbon dioxide of
6.8 x 10"16 °C/kg C02 emitted (IPCC, 2013), an estimated 1 billion metric tons of C02
emitted annually from US light and medium duty vehicle emissions would cause0.01 °C
warmingin about 15years if the emissions are not reduced (though multiple uncertainties
remain in this calculation)." Thus, the commenter argues, the temperature change arising
solely from US light and medium duty vehicle emissions would be measurable after roughly
15 years.
A commenter argues that since 2009 updates to climate models have occurred with the
newest models available under the Coupled Model Intercomparison Project 6 (Eyring et al.,
2016). The commenter states that as a group, these models have improvements to process
representation and include additional capabilities. They say that for example, advances
have been made since 2009 in the ability for model ensembles to quantify the influence of
internal climate variability on projections (Kay et al., 2015) and in model resolution. They
state that these improvements have enabled the use of models for new applications, such
as multi-year prediction of flood frequency (Zhang et al., 2025) and extending the time
horizon of tropical cyclones forecast to seasons (Murakami et al., 2025).
A commenter states that the negligible effect of the rule is confirmed by well-established
climate models used forthat purpose. They say that using MAGICC model- a simple
climate model frequently used by the EPA and the IPCC - one can analyze the effect of the
multi-pollutant rule's emissions reductions against a likely future emissions pathway
[citing M. Meinshausen, et al., The MAGICC charge model for climate change and air
pollution, 4 Geosci. Model Dev. 1443 (2011)]. They state that under the IPCC's SSP2-4.5
scenario, global temperature rises of 4.5°F (2.5°C) over the pre-industrial baseline are
projected to occur by 2100. The commenter also says that when the 7.2 billion metric tons
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of carbon-dioxide-equivalent emission reductions projected from the EPA's rule are
subtracted from this pathway through 2055, the effect on global temperature is
infinitesimal [citing"Calculation made using MAGICC7, with emissions data from the SSP
database and subtractions based on 89 FR at 28,097"]. They also say that the model
indicates the rule could reduce projected mean global surface temperatures by 0.05°F
(0.03°C) by 2100. According to the commenter, this temperature change is scientifically
and statistically meaningless - it is far too small to be detected and is at least an order of
magnitude smaller than the model's own uncertainty and the climate's natural annual
variability. The commenter says that the inescapable conclusion is that the rule's effect on
the climate is indistinguishable from zero.
One commenter stated that the EPA should utilize a different metric for consideration of
futility that is not temperature change or sea-level rise. The commenter suggested using
something like the impact on public health per ton of emission emitted.
EPA Response
The EPA generally agrees with those comments that stated that modeled temperature
change is immaterial and that the temperature change is at least an order of magnitude
smaller than the model's own uncertainty and the climate's natural annual variability. As
discussed in section V.A of the preamble, the EPA recognizes that there are significant
uncertainties related to climate modeling and recognizes that there is still significant
dispute regarding climate science and modeling. Nevertheless, the EPA performed climate
modeling in support of this final action and is utilizing that climate modeling to help
illustrate that even if we accepted the assumptions of the climate models (which the EPA
does not), that removing all GHG emissions from new LD, MD, and HD vehicles would not
materially address the health and welfare dangers attributed to global climate change
concerns in the Endangerment Finding. The EPA's climate modeling is documented in a
technical memorandum available in the docket for this final action.
The EPA utilized the EPA Optimization Model for reducing Emissions of GHGs from
Automobiles (OMEGA model) to estimate the global GHG contributions from U.S. light- and
medium duty vehicle engines, and the EPA's MOtor Vehicle Emission Simulator (MOVES
model) to estimate the global contribution from U.S. heavy-duty vehicle engines (Table 1).
The EPA used the Finite amplitude Impulse Response (v2.2.3) climate emulator model
(FaIR model) to quantify changes in global C02 concentration and global surface
temperature associated with the marginal change in emissions from each vehicle scenario
relative to the baseline. The FaIR model is an open-source emulatorthat reasonably
reflects the best available information and science but does not include all possible Earth
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system processes. In FaIR, GHG lifetimes are based on a four-box decay model that is also
a function of atmospheric and ocean temperatures and emissions of other gases. The
model accounts for radiative forcingfrom GHGs, aerosols, albedo changes due to land
use, solar cycles, and volcanic eruptions, given an externally defined time path for each.
FaIR uses three layers for the ocean component, as heat uptake by the ocean controls how
fast atmospheric temperature changes after a change in radiative forcing. FalRv2 includes
uncertainty estimates that are based on a calibration to global climate models, historical
observations, and parameter uncertainty ranges from the Intergovernmental Panel on
Climate Change. Uncertainties in climate model parameters considered in FaIR, include
the sensitivity of climate to increases in atmospheric C02 concentrations, forcing from
aerosol interactions with radiation and clouds, forcing from black carbon on snow, and
carbon cycle parameters. All simulations were run with historical volcanic and solar cycle
forcing, with values held constant (solar) after 2022.
Many of the commenters on the proposal provided climate modeling projections based on
use of the MAGICC model. The MAGICC and the FaIR models are two reduced complexity
climate models that have been widely used by the scientific community, most notably in
the Assessment Reports of the Intergovernmental Panel on Climate Change. Reduced
complexity models rely on simplified numerical expressions and parameterizations of
physical and chemical processes to efficiently emulate or replicate the output of more
complex Earth System of Global Climate models. This enables the use of reduced
complexity models to rapidly assess multiple scenarios or various aspects of climate
uncertainty. MAGICC has a decades-long history of being used for both IPCC Assessments
and Integrated Assessment Modeling (1AM), while FaIR has been developed more recently.
Both models follow the same general approach where they 1) map emissions to
atmospheric gas concentrations using gas-cycle modules, 2) map concentrations to
effective radiative forcing using forcing expressions and aerosol parameterizations, and 3)
map radiative forcing to changes in temperature using energy balance modules. Where
MAGICC and FaIR differ is in their approach to each step. For example, to convert
emissions to atmospheric concentrations, FaIR uses an impulse-response carbon cycle
and simplified chemistry for short-lived gases, whereas MAGICC uses explicit land/ocean
carbon flux equations and more detailed chemistry parameterizations. Both models,
however, can be calibrated to produce probabilistic projections of future changes in global
temperature that are consistent with the latest IPCC 6th Assessment Report (AR6). For
example, to increase the robustness of AR6, both MAGICC and FaIR were used to provide
central estimates and "likely" ranges for each future SSP warming scenario. In terms of
useability, both MAGICC and FaIR are publicly available models, but the fully transparent
and open-source nature of FaIR provides greater ease of use of FaIR for custom scenario or
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policy analyses. In its own modeling completed for this final action, the EPA ran the latest
version of FaIR with AR6-calibrated parameters. Based on a review of the public comments
submitted to the EPA in response to this proposed rule, it is unclear whether the version of
MAGICC used by the commenterwas also run using AR6-calibrated parameters.
The EPA also used the Building Blocks for Relevant Ice and Climate Knowledge (BRICK)
model to quantify changes in global sea level rise associated with the marginal
temperature changes from each vehicle emissions scenario. Commenters in general did
not identify modeling projections for global sea level rise - for details on the EPA results for
global sea level rise please see the EPA technical memorandum and the preamble for this
final action.
The EPA modeling described above projects that global atmospheric concentrations of C02
will be 420.5 parts per million by volume (ppmv) (with an associated 95 percent confidence
interval (95 percent CI) of 419.1-422.1 ppmv) in 2027 and are projected to increase in the
baseline scenario to a median of 475.4 ppmv by 2050 and 533.6 ppmv by 2100. The 95
percent CI reflects the uncertainty in the FaIR model input parameters and ranges from
461.8-484.3 ppmv in 2050 to 482.5-565.4 ppmv in the year 2100. Relative to 2027,
concentrations of C02 are projected to increase in 2050 and 2100, by 55.0 ppmv and 113.3
ppmv, respectively. GHG emissions from on-road vehicle exhaust in the United States are
projected to contribute 2.8 ppmv (or 5 percent) and 7.4 ppmv (or 7 percent) to this global
increase by 2050 and 2100, respectively, as shown in the table below.
EPA Modeling: Absolute global C02 concentrations (ppmv), by scenario*
Scenario
Estimated Media
2027
n (95% Confidenc
2050
3 Interval) (ppmv)
2100
#1 Baseline (SSP2-4.5)
#2 Baseline without All On-Road Contribution
#2a. Baseline without LD, MD Contributio
#2b. Baseline without HD Contributio
420.5
(419.1-422.1)33,34
475.4
(461.8-484.3)
172.7(459.4-481.3
173.6(460.3-482.3,
174.4(461.0-483.2,
533.6
(482.5-565.4)
526.1 (477.7-556.8)
529.0 (479.6-560.2)
530.7 (480.6-562.1)
Contributions may not sum due to rounding.
As shown in the table below, the EPA modeled global mean surface temperature (GMST) in
2027 is projected to be 1.35 °C above pre-industrial temperatures, defined as the average
between 1850 and 1900 (Table 4). GMST in the baseline scenario is estimated to increase
33 Average annual observed C02 concentrations in 2024 were 423 ppmv.Source: Trends in Atmospheric
Carbon Dioxide (C02) from: https://gmLnoaa.gov/ccgg/trends/globaLhtmL
34 Note that observed data do not exactly correspond with the modeled estimates, as the FaIR and BRICK
modeling start in 1750 (or 1850) for estimation of both historical and future projected GHG concentrations,
temperatures, and sea level rise.
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to 1.89 °C (95 percent CI: 1.44-2.37 °C) and 2.66 °C (95 percent CI: 1.86-3.87 °C) above
preindustrial temperatures by the years 2050 and 2100, respectively. These changes are
+0.53 °C (95 percent CI: 0.32-0.84 °C) and +1.28 °C (95 percent CI: 0.67-2.42 °C) above
2027 temperatures. GHG emissions from on-road vehicle exhaust in the United States are
projected to contribute to 0.013 °C (95 percent CI: 0.009-0.017 °C) of this increase in global
temperature by 2050 and 0.037 °C (95 percent CI: 0.024-0.054 °C) of this increase by 2100.
EPA Modeling: GMSTrelative to pre-industrial (1850-1900), by scenario*
Scenario
Estimated Med
2027
an (95% Confidenc
2050
e Interval) (°C)
2100
#1 Baseline (SSP2-4.5)
#2 Baseline without All On-Road Contribution
#2a. Baseline without LD, MD Contributor
#2b. Baseline without HD Contributior
1.35(1.06-1,64)35
1.89(1.44-2.37)
1.88(1.43-2.36)
1.88 (1.44-2.36)
1.88 (1.44-2.37)
2.66(1.86-3.87)
2.62(1.83-3.82)
2.63(1.84-3.84)
2.64(1.85-3.85)
Contributions may not sum due to rounding.
As summarized above, the EPA received a number of public comments in response to the
EPA proposal which included modeling of the impacts of US GHG emissions and US motor
vehicle emissions on global surface temperature. Several commenters made us of
MAGICC6 or MAGICC7 modeling as a basis fortheir comments. Based on the public
comments, the EPA was not able to verify the details of how models were run or the
specific inputs, but in general, the public comments modeling found results similar to the
EPA projections using the FaIR model. For example, one commenter modeled the
elimination of US power sector GHG emissions, which GHG emissions are of similar
magnitude to US motor vehicle emissions, and projected the impact on 2050 global
surface temperature was a 0.015 °C in 2050. As discussed above, the EPA's projection for
the impact of all on-road vehicles (LD, MD, and HD) in 2050 is a contribution of 0.013 °C,
with a 95% confidence interval of 0.009 °C to 0.017 °C, so of similar magnitude as the
commenter. Many of the commenters pointed to MAGICC modeling performed by Zycher,
which projected that a net zero scenario for all US GHG emissions (not just motor vehicles)
would change global surface temperature by 0.137 °C in 2100. Another commenter used
an assumption of linearity to project a global temperature decrease of 0.032 °C in 2100
from the elimination of all GHG emissions from US motor vehicles. The EPA's modeling
performed for this final action projects that US on-road vehicle contribution to global
surface temperature increase of 0.037 °C in 2100, with a 95 percent confidence interval of
35 GMST observations in 2024 were 1.55 (1.42-1.68) °C relative to 1850-1900 to present from
https://wmo.int/publication-series/state-of-globaL-climate-2024. The uncertainty in observed temperatures
is due to the uncertainty in temperature before 1900, due to the sparsity of observations during that period.
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0.024-0.054 °C, thus the commenters assessment is of similar magnitude as the EPA
modeling.
While not endorsing any individual commenters modeling results, the EPA finds that in
general commenters who performed climate modeling projected changes in global surface
temperature impacts similar to the EPA's modeling. As discussed in detail in section IV.C
(Eliminating GHG Emissions from Motor Vehicles and Engines Would be Futile) of the final
action, the EPA finds the modeled projected impacts from the complete elimination of
GHG emissions from US on-road vehicles to be de minimis, and as discussed in the
preamble, the impacts from potential EPA GHG standards for U.S on-road vehicles, which
would not result in a complete elimination of GHG emissions, to be even smaller and thus
also de minimis.
Regardingthe comments which cite the EPA 2010 final action for light-duty vehicle GHG
standards and modeling the EPA performed at that time, which found the projected
reductions in global temperature decreases would be 0.06-0.015 °C by 2100 and 0.06-
0.145 cm reduction in global sea level rise. This projects are also similar to the more recent
modeling the EPA performed, but even smaller.
Regardingthe comment that since 2009 there have been updates to climate models which
have made improvements and added additional capabilities, the EPA is not disputingthat
improvements have been made, and for this final action the EPA has used the FaIR model
which was developed less than a decade ago, and the version used for this final action FaIR
version 2.2.3, was released in just the past few years.
The EPA disagrees with the commenter that recommended using a different metric such as
the impact on public health per ton emitted. As discussed in this rule, the uncertainties
related to determiningthe health impacts from a ton of GHG emission is significant and the
actual impacts are too speculative to determine (especially on a per ton basis). Therefore,
we believe that the use of temperature change and sea-level rise is an acceptable metric to
show that the emissions from vehicles are de minimis.
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3 Additional Proposed Bases for Rescission of the
Endangerment Finding and Repeal of GHG Emission
Standards the Agency is Not Finalizing at this Time
3.1 Alternative Rationale for Rescission: Climate Science
As explained in section IV of the preamble for this final action, the EPA is rescinding the
Endangerment Finding on the basis of its interpretation of CAA section 202(a), under which
the EPA concludes that Congress did not authorize the Agency to regulate GHG emissions
from new motor vehicles and new motor vehicle engines to address global climate change.
That legal interpretation is sufficient to support rescission of the Endangerment Finding
and repeal of the related GHG standards.
As the EPA does not adopt or rely on the proposed scientific alternative rationale in this
final action, the Agency does not need to, and is not legally required to, summarize or
respond to comments that address that unfinalized alternative as we consider those
comments to be out of scope of this rulemaking. Therefore, comments related to climate
science are out of scope of this rulemaking. This includes, but is not limited to, comments
on the Department of Energy's (DOE) Climate Working Group (CWG).
Nevertheless, in the interest of transparency and to assist the public in understanding the
record, the EPA provides a summary of major themes raised by commenters regarding the
proposed scientific alternative rationale in section V.A. of the preamble. The EPA offers the
preamble section V.A. summary for informational purposes only. The EPA does not in this
rulemaking resolve the underlying scientific debates described below, does not issue a
new or revised scientific determination under CAA section 202(a), and does not adopt or
endorse any particular assessment, study, or comment as a statement of the EPA's
scientific judgement.
3.2 There is No Requisite Technology for Vehicles That Meaningfully
Addresses the Identified Dangers of the Six "Well-Mixed" GHGs
As explained in section IV of the preamble for this final action, the EPA is rescinding the
Endangerment Finding on the basis of its interpretation of CAA section 202(a), under which
the EPA concludes that Congress did not authorize the Agency to regulate GHG emissions
from new motor vehicles and new motor vehicle engines to address global climate change.
That legal interpretation is sufficient to support rescission of the Endangerment Finding
and repeal of the related GHG standards. As discussed in the preamble for this final action,
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the EPA does not believe that it is necessary to finalize the "no requisite technology"
alternative basis for repeal discussed in the proposed rule (see sections V.B and V.C of the
preamble for this final action).
As the EPA does not adopt or rely on this proposed alternative rationale in this final action,
the Agency does not need to, and is not legally required to, summarize or respond to
comments that address that unfinalized alternative.
3.3 More Expensive New Vehicles Prevent Americans from Purchasing
New Vehicles that are More Efficient, Safer, and Emit Fewer GHGs
As explained in section IV of the preamble for this final action, the EPA is rescinding the
Endangerment Finding on the basis of its interpretation of CAA section 202(a), under which
the EPA concludes that Congress did not authorize the Agency to regulate GHG emissions
from new motor vehicles and new motor vehicle engines to address global climate change.
That legal interpretation is sufficient to support rescission of the Endangerment Finding
and repeal of the related GHG standards. As discussed in the preamble for this final action,
the EPA does not believe that it is necessary to finalize this alternative basis for repeal
discussed in the proposed rule (see section V.D of the preamble for this final action).
As the EPA does not adopt or rely on this proposed alternative rationale in this final action,
the Agency does not need to, and is not legally required to, summarize or respond to
comments that address that unfinalized alternative.
4 Repeal of the GHG Emission Standards
4.1 Fleetwide Averaging
EPA Summary of Comments
One commenter suggested the EPA should make clear in the final action that Section
202(a) does not authorize fleetwide averaging or averaging, banking and trading (ABT) for
GHGs or any pollutant. The rule should remove ABT provisions tied to the GHG program in
40 CFR parts 85, 86, 600,1036, and 1037, and explain that any future Section 202
standards must be unit-applied limits that each vehicle or engine must meet on its own.
EPA Response
In this rulemaking, we are finalizing as proposed the removal of the EPA's GHG standards
under 40 CFR 85, 86, 600,1036, and 1037 and thus correspondingly are also removing the
option for manufacturers to comply with those standards by generating credits under the
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EPA averaging, banking, and trading program. The authority of the EPA to set standards
based on a fleetwide average is out of scope for this rulemaking.
4.2 Light- and Medium-duty Vehicle GHG Program
4.2.1 GHG Comments
The EPA proposed to remove GHG standards and related provisions from 40 CFR parts 85,
86, 600, and 1066.
EPA Summary of Comments
Manufacturers asked the EPA to establish or determine that the model year 2027 and later
GHG standards in 40 CFR 86.1818-12 and 86.1819-14 are not appropriate, even if those
standards are removed in this final action. The commenters suggested making such a
determination to prevent future rulemaking action that would simply restore the standards
as originally adopted. Some commenters suggested that we additionally name an
alternative backstop standard that would apply if circumstances lead to eventually
reinstating GHG standards.
EPA Response
We are removing the GHG emission standards forthe reasons set for in the preamble for
this final action. We are not putting in place alternative GHG emission standards.
EPA Summary of Comments
Manufacturers requested that we revise the final action to include an amendment that
removes the reference to California's 2022 on board diagnostics (OBD) requirements that
have been invalidated.
The regulation at 40 CFR 86.1806-27 incorporates California's 2022 OBD requirements by
reference. The process of adopting those standards by reference means that the full text of
those standards becomes part of the Code of Federal Regulations (CFR) even if they no
longer exist elsewhere. The new OBD requirements take effect starting in model year 2027.
We are making changes to 40 CFR 86.1806-27 to more carefully exclude requirements that
are specific to GHG emissions. The result of those changes is to limit OBD requirements to
be related only to criteria emissions. As a result, the suggested change is outside the scope
of this rule. We may revisit OBD in a later rulemaking.
EPA Summary of Comments
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Manufacturers requested that we preserve any regulatory content that the National
Highway Transportation Safety Administration (NHTSA) needs for implementing their fuel-
consumption standards for medium-duty vehicles.
EPA Response
See the discussion of this issue in Section 4.3.2.
EPA Summary of Comments
Some commenters supported the EPA's proposal to revise 40 CFR 85.2103 by removing
batteries serving as a Rechargeable Energy Storage System (RESS) for electric vehicles and
plug-in hybrid electric vehicles from the list of specified major emission control
components that are subject to warranty coverage for 8 years or 80,000 miles. Some
commenters, in written comment and in testimony at the public hearing, objected to the
proposed change. A written comment recommended keeping battery requirements to
preserve the benefits for protecting consumers. Other commenters noted that RESS
provisions are not limited to GHG emissions and that the Agency specifically connected
the warranty provisions to its NMOG+NOx standards in the 2024 Light- and Medium-Duty
rule.36
EPA Response
CAA section 207 specifies a warranty period of 8 years or 80,000 miles for specified major
emission control components. We included batteries for EVs and hybrid electric vehicles
as specified major emission control components because these vehicles were an
important part of the feasibility demonstration for the 2024 rule, which included both GHG
and criteria pollutant (specifically, nonmethane organic gases and oxides of nitrogen,
NMOG+NOx) emission standards. Considering the connection to the EPA criteria pollutant
program, which is out of scope of this rulemaking, we are not taking final action at this time
on the proposal to remove batteries serving as a RESS for electric vehicles and plug-in
hybrid electric vehicles from the list of specified major emission control components in 40
CFR 85.2103(d)(1). We may consider revisions in a future criteria pollutant rule. Note that
we are nevertheless finalizing the proposed change to remove 40 CFR 85.2103(d)(3), which
established the newly required battery monitor as the basis for making battery-related
warranty claims; since we are removingthe requirement to install these dashboard-
mounted battery monitors in this rulemaking, warranty implementation will necessarily
proceed without the benefit of information from the battery monitor.
36 89 FR 27965 (April 18, 2024).
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Earlier rules to establish battery-related requirements have described how the CAA
authorizes such requirements. We have generally created warranty provisions to align with
the statutory direction to address emission-related problems, rather than adopting
requirements solely to protect consumers' economic interests.
EPA Summary and Response
The following table addresses comments on several minor issues:
Summary of Comments
EPA Response
85.2104: Remove text related to battery requirements.
This was an oversight in the proposed rule. We have
corrected the final action as suggested.
86.1829-01: Remove text related to battery
monitoring.
This was an oversight in the proposed rule. We have
corrected the final action as suggested.
86.1844-01: Amend text to refer to criteria emissions
instead of exhaust emissions.
Evaporative emissions are also criteria emissions, so
we have instead revised the regulation to refer to
"criteria exhaust emissions".
86.1806-27: Add several GHG-related items to the list
of CARB OBD requirements that don't apply for EPA
certification.
This was an oversight in the proposed rule. We have
corrected the final action as suggested.
86.1829-15: Remove the reference to battery
requirements in 86.1815-27.
This was an oversight in the proposed rule. We have
corrected the final action as suggested.
86.1839-01: Remove text related to battery
monitoring.
This was an oversight in the proposed rule. We have
corrected the final action as suggested.
86.1844-01: Remove text related to battering
monitoring and battery durability.
This was an oversight in the proposed rule. We have
corrected the final action as suggested.
86.1847-01: Remove the reporting and recordkeeping
related to battering monitoring and battery durability.
This was an oversight in the proposed rule. We have
corrected the final action as suggested.
86.1848-01: Remove paragraphs with compliance
provisions related to battering monitoring and battery
durability.
This was an oversight in the proposed rule. We have
removed one of the identified paragraphs. We revised
two of the identified paragraphs to preserve content
unrelated to battery testing.
600.010: Remove the reference to a section that is no
longer in the CFR.
We are including this correction in the final action.
600.113-12: Retain (g)(3) for relevant instructions on
numerical quantities, and update terminology to align
with other paragraphs in this section. Also consider
the effect of rounding for converting net heat of
combustion to different units.
This was an error in the proposed rule. We are
restoring paragraph (g)(3), and amending it with
updated terminology to reflect changes in the LMDV
Tier 4 final rule. We are also clarifying that units for net
heat of combustion are Btu/pound for E0 testing, and
MJ/kg for E10 testing, with decimal places prescribed
appropriately for the different units.
Since measurements should give a result in the
appropriate units for net heat of combustion, there is
no need to consider rounding effects with those
conversions.
600.113-12: Amend several paragraphs with
corrections and clarifications related to terminology,
references, units, and calculations.
These comments are outside the scope of the current
action. We may consider these issues in a future rule.
600.116-12: Remove references to utility values that
are specific to GHG standards.
This was an oversight in the proposed rule. We have
corrected the final action as suggested.
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Summary of Comments
EPA Response
600.117: Remove the reference to GHG standards.
This was an oversight in the proposed rule. We have
corrected the final action as suggested.
600.117: Update the test instruction to reference
California's LEV IV fuel.
This comment is outside the scope of the current
action. We intend to address the issue in a future rule.
1066.815: Clarify that PM testing based on four-bag
measurements is permissible for all powertrain types.
This comment is outside the scope of the current
action. We intend to address the issue in a future rule.
4.2.2 Comments Related to Criteria Pollutant Emission Standards and Other
Provisions
EPA Summary of Comments
Manufacturers recommended several different amendments to certification and testing
provisions related to criteria exhaust emissions.
Manufacturers also suggested that we pursue amendments to allow robot drivers, and to
allow for measuring current in addition to voltage for EVs.
EPA Response
The suggested changes are outside the scope of this rule because the EPA did not propose
to change standards for criteria exhaust emissions or other testing provisions unrelated to
GHG standards. We may consider future amendments as suggested in the comments.
4.3 Heavy-duty Engine and Vehicle GHG Program
4.3.1 Comments Related to Revising Instead of Removing Heavy-duty GHG
Standards
A supplier trade organization commented that suppliers have invested heavily in
technologies that reduce GHG emissions (e.g., powertrains, including battery electric,
hydrogen, and hybrid options) and technologies that improve vehicle efficiency (e.g.,
engine system enhancements, automatic tire inflation, light-weighting, low-rolling
resistance). These programs have been essential to ensure that supplier investments
remain viable and are not rendered stranded or lost as sunk costs.
As a result of the potential removal of GHG emissions standards, the trade organization
stated that suppliers face difficult strategic decisions to mitigate the risk of stranded
investments. For example, some companies are preparingto defertooling and capital
expenditure until there is greater clarity regarding original equipment manufacturer (OEM)
demand, includingthe technologies OEMs will require, both domestically and globally. In
the interim, suppliers are limiting employment opportunities, slowing or idling production,
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and operating facilities at reduced capacity due to market uncertainty created by
continuously shifting emissions requirements and tariff pressures.
They stated that the proposed full rollback of GHG standards has already delayed critical
investment decisions and caused customers and suppliers at all tiers to delay or reverse
orders. It has also created stranded capital investment, suspended hiring, and prompted
investment freezes. These outcomes diminish the attractiveness of the U.S. market for
further investment and weaken the ability of U.S. suppliers to compete effectively in the
global marketplace. Instead, the supplier trade organization suggested the EPA consider
implementing national GHG standards at a feasible level that ensures regulatory stability,
sustains domestic investment, and maintains the global competitiveness of U.S. suppliers.
They provided specific technical feedback it hoped would address certification and
compliance challenges, reduce unnecessary costs, preserve customer choice, and
support the deployment of advanced technologies.
Another supplier trade organization noted recent changes in policies and market realities
have led to slower than anticipated EV uptake and that the rates of electrification
estimated for compliance with the EPA's GHG standards for MY 2027 and later vehicles
were ambitious. While EV technology is mature, they stated there is still considerable
uncertainty in the timeline for market penetration and they remained concerned about the
rate of charging infrastructure build-out as well as short- and medium-term availability of
sufficient critical minerals to support industry investments. In addition, unforeseen
disruptions in electrical power availability have occurred as our nation's electrical grid is
stressed by increased demand coupled with aging infrastructure. Nevertheless, the trade
organization still recommends retention of GHG standards for mobile sources and
application of GHG standards at a level that encourages continued progress in GHG
reductions based on all available technologies, including efficiency improvements in
current internal combustion engine (ICE) vehicles and electrification technology that
includes hybrids.
This supplier group suggested the EPA should revise the GHG standards to a level that
continues to incentivize technology innovation and U.S. industry competitiveness in the
global market as they are concerned that rescission of the Endangerment Finding may
increase policy risk and long-term regulatory instability which impairs their industry's
ability to effectively make investments. Clean mobility suppliers invest in developing
technology for a global automotive market many years in advance and depend on policy
stability to avoid stranded investments. The combination of downward-adjusted GHG
emission limits and life-cycle accounting of upstream emissions offers a robust and
comprehensive approach to reconsideringthe vehicle GHG emission standards. Such an
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approach treats all technologies equally and provides a stable and defensible regulatory
framework for industry to base long term investments in the U.S. auto sector.
Some industry commenters offered regulatory suggestions that the EPA could consider for
an interim final rule that would rescind the EPA HD Phase 3 program and keep the EPA's MY
2024 GHG standards in place for MY 2027 and later engines and vehicles. One
manufacturer that supported the EPA keeping GHG levels at HD GHG Phase 2 2024 MY
standards requested that the EPA retain two provisions from the HD GHG Phase 3 program:
• 40CFR 1036.150(aa), 1036.730(f)(1), 1037.150(y) and 1037.730(f)(1) credit
correction allowances
• 40 CFR 1037.150(z) credit exchange across averaging sets
Commenters that opposed an interim final action stated that halting GHG standards would
be unlawful, would not comport with the rulemaking requirements of the CAA and
Administrative Procedure Act, and that rescissions or reductions in stringency of the EPA's
vehicle GHG standards would alter significant reliance interests for manufacturers that
have already entered into contracts to trade compliance credits earned by exceeding the
standards for MY2025.
EPA Response
As described in the preamble to this final action, we are finalizing as proposed the removal
of 40 CFR 1036.108, and 40 CFR 1037.105 and 1037.106 that contained the EPA's GHG
standards. Due to the bases adopted for this final action, we are not putting in place
alternative GHG emission standards in this final action and are not committing to
alternative GHG emission standards in a separate action.37
Should this final action be challenged and the Courts opt to stay the rescission of the GHG
standards, we note that manufacturers would continue to have time to manage their
compliance strategy to meet more stringent standards that would go into effect for the
heavy-duty engines and vehicles. In this hypothetical situation, a manufacturer utilizing the
GHG ABT program would demonstrate their compliance with the MY 2027 GHG standards
at the end of the model year, with ABT reports due by September 30, 2028.38 In addition,
manufacturers have a suite of flexibilities including the ability to bank, trade, and use
credits. Furthermore, manufacturers would continue to have the flexibility to carry over
37 See section 1.3.3 of this document that summarizes and responds to additional comments related reliance
interests.
38 For example, see 40 C.F.R. 1037.730.
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GHG credit deficits for three years, which extends the period over which manufacturers
have to transition to those more stringent standards.
As described in 4.3.1 of this document, we are retaining provisions needed by NHTSA's fuel
efficiency program, but we are not retaining any of the GHG provisions established under
the EPA's Phase 3 program, including allowances to correct credit balances and exchange
credits across averaging sets. Provisions adopted under the EPA's Phase 3 program only
applied for certifying to the EPA's GHG standards and are not needed for NHTSA's fuel
efficiency program.
4.3.2 Comments Related to NHTSA's Heavy-duty Fuel Efficiency Program (C-
16 and C-17)
In the proposal, the EPA noted that NHTSA's medium- and heavy-duty fuel efficiency
regulations in 49 CFR part 535 refer to several sections in the EPA's 40 CFR parts 1036 and
1037 that we are proposing to modify or remove. We requested comment on whether any of
these provisions should be retained for the final action with a CFR notation throughout 40
CFR parts 1036 and 1037 explaining that these sections only apply to NHTSA's heavy-duty
fuel efficiency program (C-16).
Also in the proposal, the EPA noted that NHTSA's reporting and recordkeeping regulation in
49 CFR 535.8(a)(6) directs manufacturers to submit information to the EPA and the EPA
then shares that information with NHTSA. We requested comment on the time required to
transition from requiring manufacturers to supply relevant data to the EPA to requiring that
they supply the data directly to NHTSA (C-17).
EPA Summary of Comments
Commenters, including engine and vehicle manufacturers, reiterated that NHTSA relies on
the EPA's GHG regulations for its medium- and heavy-duty fuel efficiency program and
removing the EPA's regulations before NHTSA has revised their regulations would make it
challenging for NHTSA to implement their program. Some commenters suggested the EPA
retain the sections NHTSA relies on until NHTSA has the necessary regulations in place to
continue to implement their program. These commenters also supported the EPA revising
the retained GHG regulations to note that the provisions are only applicable for NHTSA's
program. One commenter specifically requested that the EPA work with NHTSA during the
transition.
Several commenters identified specific regulatory sections that they believed should be
retained for NHTSA's fuel efficiency program.
EPA Response
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In general, we agree with commenters that manufacturers should continue to have access
to the regulations needed for NHTSA to effectively implement their program. At this time,
NHTSA has not finalized regulations to update their heavy-duty fuel efficiency program
under 49 CFR part 535. As such, and as we discuss in the preamble to this final action, we
are retaining most of the regulatory provisions cited by NHTSA.
We are finalizing as proposed the removal of 40 CFR 1036.108, and 40 CFR 1037.105 and
1037.106 that contained the EPA's GHG standards, and we have generally replaced
references to "C02 standards" with "fuel consumption standards" throughout 40 CFR parts
1036 and 1037. We note that we have not removed all references to C02 emissions
throughout these parts. C02 emissions remain the basis of many of the test procedures
and compliance provisions used in NHTSA's fuel efficiency program. As such, we are
retaining many of the requirements to measure and report C02 emissions in 40 CFR parts
1036 and 1037 to support the NHTSA's fuel efficiency program.
Relatedly, and as discussed in the preamble to this final action, we are retainingthe
provisions that require manufacturers to submit their compliance data and information to
the EPA. At this time, the EPA intends to continue to maintain its Engines and Vehicles
Compliance Information System (EV-CIS) and manufacturers would continue to have an
EPA Designated Compliance Officer for submitting information regarding NHTSA's fuel
efficiency program. However, we note that the EPA would no longer issue EPA certificates of
conformity for GHG emissions or analyze end of year reports for compliance with the GHG
emission standards. Furthermore, the EPA will perform confirmatory testing, in-use testing,
or selective enforcement audits only in relation to the EPA criteria pollutant program. We
note that vehicle manufacturers will continue to have access to the GEM Phase 2, Version
4.0 that is incorporated by reference in 40 CFR 1037.810 and currently available on the
EPA's website; however, the EPA does not intend to continue to maintain or update the GEM
tool used to demonstrate compliance with NHTSA's fuel efficiency program in the future.
To facilitate addressing commenters' requests to retain the EPA's regulatory provisions
needed by NHTSA, we are finalizing two overarching provisions in 40 CFR parts 1036 and
1037 to clarify how the regulations apply for NHTSA's fuel efficiency program. First, we are
adding new paragraphs 40 CFR 1036.1 (e) and 40 CFR 1037.1(c) to clarify that these parts
do not establish standards for C02 or other GHG emissions, but they do include
certification and testing provisions related to C02 emissions to support the fuel
consumption standards adopted by NHTSA under 49 CFR part 535. Second, to avoid
extensive revisions throughout the parts, we are updating the definition of "we (us, our)"
from "the Administrator of the Environmental Protection Agency and any authorized
representatives" to instead mean "the Administrator of the Environmental Protection
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Agency and any authorized representatives for issues related to criteria pollutant
standards. In the case of testing, compliance, and approvals related to fuel consumption
standards, "we (us, our)" includes the Administrator of the National Highway Traffic Safety
Administration (NHTSA) and any authorized representatives."
By retaining the EPA's regulations to support NHTSA's fuel efficiency program, we can
continue to refer to those provisions throughout 40 CFR parts 1036 and 1037 for the EPA's
criteria pollutant program. For example, since the NHTSA program continues to use the
term "family certification level (FCL)", the vehicle family definitions, the test procedures of
40 CFR 1037, subpart F, and the duty cycles in the 40 CFR part 1037 appendices, it is no
longer necessary to remove or redefine references to those provisions for those to be
available for the EPA's use. While we are retaining those provisions, we have made some
revisions to remove explicit references to the EPA standards that no longer exist, and to
clarify when a provision only applies to NHTSA's fuel efficiency program.
We note that the revised 40 CFR part 1037 continues to contain provisions that apply for
most heavy-duty vehicles under NHTSA's fuel efficiency program; however, it applies for
fewer vehicles under the EPA's criteria pollutant program. Without the EPA GHG standards,
there are no vehicle-level emission standards for vehicles (including glidervehicles) with
engines certified to other parts. While are retaining the provisions of 40 CFR 1037.605 for
specialty vehicles for NHTSA's program, we are removing the vehicle labeling requirements
for the EPA's program and specialty vehicles would no longer require a certificate of
conformity from the EPA; the EPA certificate would be held by the engine manufacturer
certifying under the engine provisions of 40 CFR 1036.605. Under this final action, the only
heavy-duty vehicles that would continue to require a vehicle-level certificate of conformity
from the EPA are those with no installed propulsion engine, BEVs and FCEVs, certifying to
the criteria pollutant standards of 40 CFR 1037.102. Tailpipe emissions of criteria
pollutants from BEV and FCEV manufacturers would continue to be deemed to be zero with
no testing requirements, but the EPA would still require that BEV and FCEV manufacturers
apply for a certificate of conformity to meet the requirements of CAA 202(a).
If NHTSA updates their regulations and is prepared to accept the manufacturers' data and
information directly, then the EPA would consider a separate rulemaking to remove the
remaining provisions related to the NHTSA fuel efficiency program, including the EPA's data
collection responsibilities.
We respond to the requests to retain or revise specific provisions for NHTSA's fuel
efficiency program in sections 4.3.3 through 4.3.4.
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4.3.3 Comments Related to Specific Provisions in the Heavy-duty Engine
Program under 40 CFR 1036
In this section 4.3.3, we summarize and respond to detailed comments related to specific
heavy-duty engine regulations under 40 CFR part 1036. Comment summaries and
responses are presented in tables by regulatory subpart. See Table 4-1 through Table 4-5.
Table 4-1 Comments related to 40 CFR 1036, subpart B
Summary of Comments
EPA Response
40 CFR 1036.108 - Commenters suggested to retain
because it is referenced by NHTSA at 49 CFR
535.6(d)(2).
We are removing 40 CFR 1036.108 as proposed
because we are removing all EPA standards for GHG
emissions in this final action. We note that the NHTSA
reference is for the number of decimal places
manufacturers should measure their C02 emission
rates to calculate the equivalent fuel consumption
rates. Each of the standards originally published in 40
CFR 1036.108 were set to whole number values, so
manufacturers would round measured C02 emission
rates to 1 decimal place to calculate their fuel
consumption rates.
40 CFR 1036.110 - This section references CARB
Heavy-Duty OBD that requires tracking of "Active
Technology(ies)", tracking of C02 parameters, and
reporting C02 emission results during an OBD
demonstration test. Commenters request the EPA's
OBD regulation exclude the requirements to track
GHG related parameters in the OBD data stream,
such as "Active Technology(ies)" and other
parameters related to fuel consumption, and 7 the
requirement to measure and report C02 emissions
during OBD Durability Demonstration Engine testing.
We are adding new paragraphs (14) through (18) to 40
CFR 1036.110(b) to exclude the definition of "Active
Technology" and related standardization, data
storage, certification documentation, and monitoring
system demonstration requirements from the EPA
OBD provisions under 40 CFR 1036.101.
40 CFR 1036.115(b) Commenters suggested to retain
for fuel mapping.
We are retaining the existing 1036.115(b).
Table 4-2 Comments related to 40 CFR 1036, subpart C
Summary of Comments
EPA Response
40 CFR 1036.230 - Commenters suggested to retain
because it is referenced by NHTSA at 49 CFR
535.6(d)(3)(i).
We proposed to remove paragraph (f) from 40 CFR
1036.230; however, we are retaining 40 CFR
1036.230(f) in this final action with revisions. The
revised text replaces references to the EPA GHG
standards with a reference to 40 CFR part 535, and
removes reference to GHG emission controls in
paragraph (f)(5). We note that, under this final action,
manufacturers would need to obtain approval from
NHTSA to produce non-tested configurations under
paragraph (f)(5).
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Summary of Comments
EPA Response
40 CFR 1036.235 - Commenters suggested to retain
because it is referenced by NHTSA at 49 CFR 535.6
The EPA proposed to define the term eCo2FTP as brake-
specific C02 emissions over the FTP (or SET with
advance EPA approval), to be used as a reference
value for calculating emissions rates from in-use
engines under §1036.530, instead of eCo2FTPFCL since
the EPA proposed to remove the C02 FCL. A
commenter requested additional clarification
regarding how to determine eCo2FTP. For example, it is
unclear as proposed whether it should be adjusted for
specific net energy content (as described in
§1036.550(b), also proposed for removal) in the same
way C02 emissions results would have been adjusted
in the past. As another example, it is unclear how to
determine FTP C02 for plug-in hybrids where the C02
emissions may vary across test cycles during the
charge-depleting sequence.
We are retaining 1036.235 with revisions.
We are replacing references to the EPA GHG
standards with a reference to 49 CFR part 535 and to
replace references to GHG testing with fuel
consumption testing.
We are retaining the text we proposed to migrate from
1037.235(a) as a new 1036.235(a)(4). We recognize
that this text is now duplicative of the text from part
1037 but limits the need for manufacturers certifying
to the EPA's criteria pollutant program to review
provisions from part 1037.
We are not finalizing our proposed term eCo2FTP for
brake-specific C02 emissions over the FTP. We
proposed the new term as a replacement for eCo2FTPFCL
when we proposed to remove references to FCL. We
are now retaining FCL throughout part 1036 and are
retaining 1036.235(b) with the following revisions:
- We are adding a note to paragraph (b)(1) that off-
cycle testing depends on the value of eCo2FTPFCL from
§ 1036.530 to clarify that the term still applies for
the EPA's criteria pollutant program
- We are replacing references to "certifying" with
"testing"
- We are removing CH4 and N20 that were the EPA-
only pollutants.
40 CFR 1036.245(c) - Commenters stated engine
manufacturers continue to need the Heavy-duty
Transient Test Cycle (1037 Appendix A) and the Heavy-
duty Grade Profile for Steady-State Test Cycles (1037
Appendix D), as optional test cycles for the engine
deterioration factor test. Request Appendix A and
Appendix D from § 1037 be moved to § 1036 regulation
and the EPA should retain the option currently allowed
in 1036.245(c)(3)(H) to use those cycles as part of
service accumulation.
Another commenter requested the EPA retain the
Diesel Aftertreatment Accelerated Aging Cycle
(DAAAC) procedures of 40 CFR Part 1065 as
referenced in 40 CFR 1036.245
We are retaining all appendices from 40 CFR parts
1036 and 1037 for NHTSA and are also retaining the
existing 40 CFR 1036.245(c)(3). The EPA may consider
moving the part 1037 appendices to part 1036 in a
future rule.
We did not propose changes to the DAAAC procedure
referenced in 1036.245 and it will continue to be
available for engine certification for the EPA's criteria
pollutant program.
Table 4-3 Comments related to 40 CFR 1036, subparts D and E
Summary of Comments
EPA Response
40 CFR 1036.301 (b), (c), and (d) - Commenters stated
the GEM model is used for both NHTSA and the EPA
We are retaining 30 CFR 1036.235 including the
original references to fuel maps. We are revising the
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Summary of Comments
EPA Response
compliance, and selective enforcement audits should
remain valid for those inputs.
section heading to the more broadly-applicable
"Selective enforcement audits."
We note that, under this final action NHTSA would
perform any selective enforcement audits related to
fuel maps and GEM inputs.
40 CFR 1036.415: Commenters stated that some of
the proposed language regarding "adjustable" and
"not adjustable" neutral idle could lead to confusion
about allowable overrides for idle reduction
technologies that were previously required to be
"tamper resistant." "Adjustable" and "non-
adjustable" language in 1036.415 is insufficiently
clear.
We are retaining the existing 1036.415 because we are
keeping 1036.530 and 1037.520 and 1037.660 that are
referenced in this section.
Table 4-4 Comments related to 40 CFR 1036, subpart F
Summary of Comments
EPA Response
Commenters stated Subpart F (1036.501-1036.580)
must remain in place until NHTSA eliminates
references to these sections or the fuel consumption
standards for HD engines would lack any certification
process. Subpart F defines all the GEM parameters,
and their derivation and use to calculate fuel
efficiency values for each vehicle. Without Subpart F
there can be no determination of a vehicle's
performance against the NHTSA Heavy-Duty Fuel
Efficiency standards.
We agree and are retaining subpart F for NHTSA in this
final action, with some edits to remove reference to
the EPA standards, GHG emissions, or other
requirements that only applied for the existing EPA
program in 40 CFR part 1036.
40 CFR 1036.501 (h) - Commenters stated the EPA has
erroneously proposed eliminating 1036.505,
references to which are deleted here. GEM is core to
compliance with both NHTSA and the EPA and is
explicitly referred to at 49 CFR § 535.6 for
measurement and calculation procedures.
We are retaining 1036.505 with revision (see below)
and retaining the existing 1036.501(h).
40 CFR 1036.505 - Commenters stated the GEM
model is used for both NHTSA and the EPA
compliance, and selective enforcement audits should
remain valid for those inputs.
A commenter also stated that the EPA is the agency
better positioned to provide such audits, owing to the
National Vehicle and Fuel Emissions Laboratory in
Ann Arbor, Ml, which is equipped with appropriate test
equipment to validate manufacturer data for both
light- and heavy-duty vehicles.
We are retaining 1036.505 with revisions to replace
references to the EPA GHG standards with a reference
to 49 CFR part 535.
Under this final action, the EPA will only perform
confirmatory testing, in-use testing, or selective
enforcement audits related to its criteria pollutant
program; NHTSA would perform any necessary testing
for its fuel efficiency program.
40 CFR 1036.510(b)(2)
Commenters stated:
The use of the SET ramped modal cycle of 40 CFR
1036.510 should be retained for testing to both the
We did not propose to remove the use of the SET
procedure for use in the EPA's criteria pollutant
program and it will remain available.
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Summary of Comments
EPA Response
criteria pollutant standards and the GHG emissions
standards of 40 CFR Part 1036.108.
Commenters suggested to delete references to
§1036.545(g)(4), § 1036.545(j), and vehicle parameters
defined in § 1036.545.
In 1036.510(b)(2)(vii), the EPA's proposed removal of
C02 as the basis for determining the worst-case
combination of vehicle model parameters for hybrid
criteria pollutant certification makes it unclear which
pollutant emissions should be considered. The EPA
should either retain C02 as the basis or change to fuel
consumption for consistency with the existing test
procedure.
40 CFR 1036.510(b)(2)(viii) - Commenters suggested
to correct table name to reference to paragraph
(b)(2)(viii)
We are retaining C02 as the basis for determining the
worst-case combination for vehicle model
parameters in 1036.510(b)(2)(vii) and adding the word
"emissions" for clarity.
We are retaining 1036.545(g) and (j) for NHTSA, so it is
no longer necessary to delete those references in
1036.510(b)(2).
Even though we are retaining 1036.540(c) for NHTSA,
we are finalizing as proposed the new table 1 in
paragraph (b)(2)(viii) and related text describing the
modeling parameters that we proposed to copy from
1036.540(c) to 1036.510(b)(2)(viii). This approach will
allow the SET procedure to be less dependent on the
fuel mapping procedure of 1036.540 that does not
apply for the EPA's criteria pollutant program. We did
correct the paragraph reference in the table name as
suggested by commenters.
40 CFR 1036.512(e) - Commenters suggested to
retain for NHTSA
We are retaining paragraph (e) for NHTSA's fuel
efficiency program with revisions to replace
references to GHG with C02, which manufacturers
would continue to measure for their fuel consumption
calculations.
40 CFR 1036.514(b)(4) - Commenters suggested to
delete reference to § 1036.510(e)
Corrected. We agree that the low load cycle is an EPA-
only test procedure, and we would no longer need to
reference 1036.510(e) that describes measuring C02
for plug-in hybrid powertrains over the SET cycle.
40 CFR 1036.520(b)(1) - Commenters suggested to
correct § 1036.510(b)(2)(vii) reference to be
§1036.510(b)(2)(viii)
Corrected.
40 CFR 1036.530
One commenter expressed concern with the use of
C02 as a surrogate for work, noting that it is not
always representative of engine thermal efficiency
during off-cycle testing, resulting in inaccurate brake-
specific criteria pollutant emissions. The commenter
requested the EPA add an option to allow
manufacturers to use broadcast engine torque and
engine speed to determine work performed over the
off-cycle duty cycle for use in these calculations, in
the same way it is allowed for non-carbon-containing
fuels in 1036.530(j). Similarly, they suggested the EPA
should allow the same option for high GCWR
medium-duty vehicles subject to off-cycle testing
prescribed in 86.1845-04(h).
The commenter also requests that the EPA specifies
in the regulation that the EPA will perform any of its
off-cycle testing using the same methodology as the
manufacturer selected at the time of certification.
We are retaining the existing term eCo2FTPFci_. The
request for a new option to allow the use of broadcast
engine torque and engine speed to determine work for
heavy-duty and high GCWR medium-duty vehicles is
out of scope for this rule. We may consider this or
other options in a future rule. At that time, we may
also consider whether the EPA would commit to using
the same methodology as the manufacturer in its own
in-use testing.
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Summary of Comments
EPA Response
40 CFR 1036.535 - Commenters suggested this is
used for NHTSA compliance and should remain.
We are retaining 1036.535 and 1036.540 with
revisions to replace references to the EPA GHG
40 CFR § 1036.540 - Commenters suggested this is
used for NHTSA compliance and should remain.
standards with a reference to 49 CFR part 535.
40 CFR 1036.543 - Commenters suggested this is
needed to verify the carbon balance error, given that
some OEMs may use carbon balance for exhaust flow
and emission calculations.
We are retaining the existing 1036.543.
40 CFR 1036.545 - Commenters suggested the
proposed deleted text of (a)(7) is likely the result of
conflating "carbon balance" with "greenhouse gas
emissions" when this is just a general practice for fuel
economy testing. They stated that the regulatory text
of paragraphs (g), (h), (n), and (o) fundamentally
underpin compliance with the NHTSA program
because GEM and its inputs are core to that
compliance. Some additional deletions refer to
sections that we have already identified as being
necessary to carryforward.
We are revising 40 CFR 1036.545 to replace
references to Phase 2 and Phase 3 standards under
part 1037 with a reference to 49 CFR part 535.
We are removing as proposed 40 CFR 1036.545(a)(1)
and (k), which refer to measuring NOx emissions.
We are retaining the existing 40 CFR 1036.545(a)(5)-
(8), (g), (h), (n), and (o) and the references within
1036.545 to other sections we proposed to delete but
are retaining in the final action.
A commenter suggested a narrower alteration could
be "Data that vehicle manufacturers need for
demonstrating compliance with vehicle fuel efficiency
standards, including fuel consumption data as
described in §§ 1036.535 and 1036.545, also qualify
as emission data for purposes of confidentiality
determinations." This policy would be consistent with
the treatment of other relevant manufacturer-
submitted data.
We are finalizing as proposed the revisions to
1036.545(d) with identical text from 40 CFR 1037.565
so that it is within the powertrain test procedure in 40
CFR part 1036 and avoid reference to a separate
vehicle test procedure in 40 CFR part 1037.
40 CFR 1036.545(f) - One commenter suggested
corrections for several references to § 1036.545(h) to
instead reference vehicle parameters defined in §
1036.510, §1036.512, and §1036.514, as appropriate.
40 CFR 1036.580(c)-A commenter suggested a
correction to a typographical error through adding
back the word "for" before "individual pollutants"
Corrected
Table 4-5 Comments related to 40 CFR 1036, subparts G, H, 1, and appendices
Summary of Comments
EPA Response
40 CFR 1036.605(b) - A commenter suggested to
delete the redundant use of the phrase "using the
same duty cycles that apply under 40 CFR part 1039"
We are finalizing the proposed revision to 1036.605(b)
except that we applying the correction raised in
comment to remove the inadvertently duplicated
phrase.
40 CFR 1036.705(b) - A commenter suggested in the
example calculation, "c = 10-6" should be "c = 10-9"
Corrected
40 CFR § 1036.730 -A commenter suggested to retain
because it is referenced by NHTSA at 49 CFR § 535.6
(d)(3)(i).
We are retaining for NHTSA the use of the term "FCL"
and references to 1036.745 throughout part 1036 with
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Summary of Comments
EPA Response
a clarifying edit to note that 1036.745 is an allowance
for NHTSA's fuel efficiency program.
We are removing as proposed the option for
manufacturers to contact the EPA regarding GHG
emission credits under 1036.730(f)(1). Manufacturers
would have to notify NHTSA for any errors they identify
for NHTSA's fuel efficiency program.
40 CFR §1036.755 - Several commenters did not think
it necessary to delete 40 CFR §1036.755. One
commenter suggested the EPA would be playing the
same role it already plays in the light-duty vehicle
sector.
We are retaining the existing 1036.755; see the final
action preamble and section 4.3.1 of this Response to
Comments document.
40 CFR 1036.801 - Commenters requested the EPA
retain several definitions for NHTSA.
We are retaining all definitions in 1036.801 for NHTSA
with some revisions to remove reference to C02
standards or GHG emissions.
As proposed, we are migrating40 CFR 1037.230 to a
new 40 CFR 1036.230 for selecting engine families.
Similarly, as proposed, we are adding definitions in
1036.801 for several terms used in the new 40 CFR
1036.230, includingAutomated manual transmission
(AMT), Automatic transmission (AT), Axle ratio or Drive
axle ration (ka), drive idle, Gear ratio orTransmission
gear ratio (kg), Manual transmission (MT).
40 CFR 1036.810 - A commenter suggested 40 CFR
1036.810 references to ASTM D3588 98 (Calc Heat
Value) & ASTM D4809 18 (Heat of Combustion of
Liquid HC Fuels) should be retained references in
either the EPA or NHTSA regulatory structure for
NHTSA calculations to adjust fuel consumption
values.
We are retaining the existing 1036.810, includingthe
references suggested by the commenter.
40 CFR § 1036.815 -A commenter suggested that the
deleted sentence should instead be modified, since
§§ 1036.535 and 1036.545 should be left in. A
narrower alteration could be "Data that vehicle
manufacturers need for demonstrating compliance
with vehicle fuel efficiency standards, including fuel
consumption data as described in §§ 1036.535 and
1036.545, also qualify as emission data for purposes
of confidentiality determinations." This policy would
be consistent with the treatment of other relevant
manufacturer-submitted data.
We are retaining 1036.815(b) with a revision to remove
"greenhouse gas emission" as a qualifier for the
standards.
Appendix C to 40 CFR 1036 -A commenter suggested
to retain the default engine fuel maps because they
help reduce the test burden on manufacturers and are
key to modeling compliance of NHTSA's program.
We are retaining the existing Appendix C to 1036.
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4.3.4 Comments Related to Specific Provisions in the Heavy-duty Vehicle
Program under 40 CFR 1037
In this section 4.3.4, we summarize and respond to detailed comments related to specific
heavy-duty vehicle regulations under 40 CFR part 1037. Comment summaries and
responses are presented in tables by regulatory subpart. See Table 4-6 through Table 4-12.
Table 4-6 Comments related to 40 CFR 1037, subparts A and B
Summary of Comments
EPA Response
40 CFR 1037.5 (d) - A commenter suggested that
NHTSA's MD/HD program explicitly refers to
exemptions in 40 CFR Part 1037, and it is likely that
this exclusion is one with overlapping jurisdiction that
is not otherwise specified in 49 CFR § 535.
We are removing as proposed 1037.5(c) and (d).
NHTSA has its own regulations under 49 CFR 535.3(d)
to exclude certain vehicles and it is not necessary for
the EPA to retain those exclusions in 40 CFR part
1037.
40 CFR 1037.105 (h) - A commenter suggested that
should be retained to ensure the EPA can maintain a
reasonable level of flexibility in their approach to
hybrid certification for low volume applications that
nurture innovation at the end use level, tailored to
specific heavy-duty vehicle applications that have
high performance needs to maintain infrastructure
and public services. This flexibility could be useful for
criteria pollutant certification requirements.
We are removing all of 1037.105 as proposed. While
this section is referenced by NHTSA for custom
chassis, 40 CFR 535.5(b)(6) largely duplicates the EPA
text.
40 CFR 1037.120-Warranty
See Table 4-7.
40 CFR 1037.130 - A commenter pointed out a
potential typographical error in subsection
1037.130(b)(4)(i). The " Basic Vehicle Frontal Area"
definition was deleted in section 1037.801 but
remains as an example in subsection
1037.130(b)(4)(i).
We are retaining 1037.801 and the referenced
definition for "basic vehicle frontal area".
Table 4-7 Comments related to 40 CFR 1037, subpart C
Summary of Comments
EPA Response
40 CFR 1037.205 - A commenter noted that emissions data
is required for NHTSA compliance and removingthe current
list of required data at (e) would also impede compliance
with NHTSA.
Some commenters note that the EPA does not have
authority to delete reporting requirements needed by
NHTSA's program because it would alter the MD/HD
NHTSA regulations. Others note that setting up new vehicle
families that are vastly different than the NHTSA
requirements would create notable changes to vehicle
compliance labels, to the computer systems that support
the tracking and labeling of vehicles, and to the reporting
systems that would need to create a new vehicle report for
the EPA end-of-year reporting. This commenter requested
We are retaining 1037.205 for NHTSA with
revisions as follows:
We are removing reference to greenhouse
gas and hybrid vehicles in paragraph (b).
Hybrids will be certifying under 40 CFR part
1036.
We are removing paragraph (c) because it is
related to air conditioning leakage standards
that only applied for the EPA
We are removing paragraph (q) because it
describes battery performance monitoring
that only applied for the EPA
We revised paragraph (t) to remove the
example related to emission credits.
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Summary of Comments
EPA Response
the EPA allows manufacturers the option to continue to use
the vehicle family names that were specified in the GHG
regulation and that align with the NHTSA regulation.
40 CFR 1037.225 - A commenter noted this provision
allows regulated entities to amend their certification
applications and the EPA proposed to remove references to
GHG requirements. It does, however, leave reference to
changing the Family Emission Level ("FEL") for vehicle
families. Since there are no emissions standards for
vehicles remaining in 40 CFR 1037, there are no FELs that
are certified. Therefore, § 1037.225(f), § 1037.801 and all
other references to vehicle FEL should be deleted from §
1037.
We are retaining the provisions of this part that
refer to FELs (and FCLs). They are generally
presented for reference in the medium- and
heavy-duty vehicle fuel efficiency program
administered by NHTSA under 49 CFR part 535.
There are no applicable C02 standards for
engines under this part.
40 CFR 1037.230 - the EPA proposed to remove the vehicle
regulatory subcategories previously defined, replacing
them with a simplified definition aligned with proposed 40
CFR 1037.102. A commenter noted without the previous
definitions of vehicle regulatory subcategories, it will not be
possible to align vehicle families with their respective fuel
efficiency standards found in the NHTSA Heavy-Duty Fuel
Efficiency regulation.
In paragraph (a) one commenter sought clarification on the
applicability of hybrid electric vehicles to the Proposed
Rule. They noted hybrid electric vehicles were not
specifically called out to categorize them in a single vehicle
family and these vehicles were mentioned in subsection
1037.205(d).
We agree with commenters that separate EPA
vehicle families may cause confusion and
unnecessary extra reporting requirements for
manufacturers certifying their vehicles to
NHTSA's fuel consumption standards.
Therefore, we are not revising the vehicle
families as proposed and are retaining 1037.230
with revisions. We are finalizing revisions to
remove references to GHGs and replace
references to C02 emission standards fuel
consumption standards.
Regarding hybrids, under this final action,
manufacturers would certify hybrid systems to
the engine standards of 40 CFR part 1036.
40 CFR 1037.231 Powertrain families. Commenters
suggested the EPA retain the sections NHTSA relies on until
NHTSA has the necessary regulations in place to continue
to implement their program.
We are finalizing as proposed the migration of
the powertrain family provision from 40 CFR
1037.231 to a new 40 CFR 1036.231. We are
retainingthe section number and heading of
1037.231 for NHTSA and are adding new
introductory text that includes a reference to the
new 40 CFR 1036.231.
40 CFR 1037.232 Axle and transmission families.
Commenters suggested the EPA retain the sections NHTSA
relies on until NHTSA has the necessary regulations in
place to continue to implement their program.
We are retainingthe existing 1037.232.
In 40 CFR 1037.250(a), the proposed regulatory text
removed the requirement to report production numbers by
vehicle identification number (VIN) but instead the
reporting is by engine family. One commenter
recommended leaving in the requirement to report by VIN.
They stated that reporting by engine family would present a
problem for zero-emission vehicles (ZEVs) which do not
have an engine family. Additionally, reporting by VIN helps
keep track of each vehicle and helps identify which engine
and vehicle families are applicable for a given vehicle.
We are retainingthe existing 1037.250, including
the requirement to report production numbers
by vehicle identification number.
We are retaining 1037.801 and the referenced
definition for "small manufacturer."
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Summary of Comments
EPA Response
The commenter noted that "small manufacturer" is
mentioned in this paragraph (a), but "small manufacturer"
definition was deleted in section 1037.801.
Table 4-8 Comments related to 40 CFR 1037, subparts D and E
Summary of Comments
EPA Response
40 CFR 1037.301 - Overview of measurements related
to GEM inputs in a selective enforcement audit.
Commenters suggested the EPA retain the sections
NHTSA relies on until NHTSA has the necessary
regulations in place to continue to implement their
program.
We are retaining all of the existing 1037, subpart D,
consisting of §§ 1037.301 through 1037.320. We note
that the GEM compliance tool continues to refer to
"FEL C02 Emissions" in support of calculations for
NHTSA's fuel efficiency program, but that the EPA's
C02 emission standards no longer apply.
40 CFR 1037.401 - Commenters suggested that the
language regarding the general provisions should be
retained to allow in-use testing at the vehicle level,
which is needed for enforceability of criteria pollutant
standards in the field.
We are retaining the existing 1037.401, but note that
the provisions of part 1037 do not impact the criteria
pollutant in-use testing requirements for engines
specified in 40 CFR 1036, subpart E.
Table 4-9 Comments related to 40 CFR 1037, subpart F
Summary of Comments
EPA Response
40 CFR part 1037 Subpart F, consisting of §§ 1037.501
through 1037.570
Commenters noted that subpart F defines all the GEM
parameters, and their derivation and use to calculate
fuel efficiency values for each vehicle. Without
Subpart F there can be no determination of a vehicle's
performance against the NHTSA Heavy-Duty Fuel
Efficiency standards.
We are retaining most of the existing 1037, subpart F,
for NHTSA, except as described below.
In 1037.501,1037.520, and 1037.540, we are
replacing references to C02 standards with fuel
consumption standards and 49 CFR part 535.
We are adding a new 1037.550 with the section
heading of "Powertrain testing" and introductory text
that points readers to 40 CFR 1036.545. The EPA
migrated the powertrain test procedure from part
1037 to part 1036 in the 2023 Low NOx rule and
NHTSA's regulations were not revised to update their
reference to that procedure.
In 1037.551(a), we are removing the requirement for
manufacturers to measure NOx emissions, which is
an EPA-only requirement.
We are retaining 1037.555 with an edit to replace
"greenhouse gas emissions" with "C02 emissions".
In 1037.560(b)(4), 1037.565(b)(3), and
1037.570(a)(4)(i), we are revising the statement that
manufacturers can use lower-viscosity gear oil if it is
approved as "critical emission-related maintenance
under §1037.125" (an EPA-only provision) and instead
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EPA Response
allowing that they can use lower-viscosity gear oil with
approval.
Table 4-10 Comments related to 40 CFR 1037, subpart G
Summary of Comments
EPA Response
40 CFR 1037.601 (d) - A commenter noted the
"Emergency Vehicle" definition was deleted in section
1037.801 but remains as an example in subsection
1037.601(d).
We are retaining 1037.801 and the referenced
definition for "emergency vehicle."
40 CFR 1037.605 - Installing engines certified to
alternate standards for specialty vehicles.
Commenters suggested the EPA retain the sections
NHTSA relies on until NHTSA has the necessary
regulations in place to continue to implement their
program.
We are retaining the provisions of 40 CFR 1037.605 for
specialty vehicles for NHTSA's program, but we are
removing the vehicle labeling requirements for the
EPA's program and specialty vehicles would no longer
require a certificate of conformity from the EPA; the
EPA certificate would be held by the engine
manufacturer certifying under the engine provisions of
40 CFR 1036.605.
40 CFR 1037.610-Acommenter noted that the
language regarding vehicles with off cycle technology
should be partially retained so that A to B testing can
be completed on vehicles for criteria emissions
reductions technology applied at the vehicle level.
We are retaining 1037.610 with revisions to replace
reference to C02 emissions reductions with fuel
consumption reductions.
40 CFR 1037.615 Advanced technologies.
Commenters suggested the EPA retain the sections
NHTSA relies on until NHTSA has the necessary
regulations in place to continue to implement their
program.
We are retaining 1037.615 with revisions to remove:
- Reference to the EPA-only HD Phase 3 program in
paragraph (a);
- Paragraph (b)(4) that refers to generating the EPA
credits under 1037.705 that we are removing; and
- Paragraph (f) that has equivalent content in NHTSA's
49 CFR part 535 regulations.
We are also revising paragraphs (g) and (h) to remove
reference to "emissions".
40 CFR 1037.620 Responsibilities for multiple
manufacturers. Commenters suggested the EPA
retain the sections NHTSA relies on until NHTSA has
the necessary regulations in place to continue to
implement their program.
We are revising 1037.620(a)(2) to state that the
requirements applytothe manufacturer that
"certifies" instead of the previous phrase "obtains the
certificate of conformity". We are also removing
reference to the Clean Air Act in paragraph (e),
because NHTSA would not be requiringany
information under that authority.
40 CFR 1037.621:
One commenter requested that the language
regarding delegated assembly should be retained for
hybrid components for power take off that can reduce
criteria emissions pollutants with components that
are applied at a vehicle level.
Another commenter suggested that 1037.621 (g)
specifically limits what changes can be made to
components related to certified configurations,
including that the changes must take place before the
We are retaining the existing 1037.621. We are not
revising paragraphs (b), (d), or (g) as proposed.
While we are retaining the existing approval process in
the regulation of 1037.621, the EPA would no longer
be granting approval. Manufacturers would request
any approvals from NHTSA for changes that may
impact fuel consumption. As such, we are not revising
the regulations to add clarifications as suggested by
the commenter for what NHTSA may or may not
approve.
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EPA Response
vehicle has been delivered to the ultimate purchaser.
This regulation gives examples of permissible changes
including "from one certified axle ratio to another."
This restriction often limits customer choice, and
strands dealers and manufacturers with trucks that
could otherwise be sold and put into service if only a
minor change can be made. The commenter
requested that the EPA clarify that manufacturers are
allowed to approve changes to vehicles that were
certified to previously-existing standards (such as the
current Part 1037 requirements) as long as those
changes do not cause the vehicle to be non-compliant
with the new Part 1037 requirements. This would give
manufacturers needed certainty that they could
approve changes to axle ratios, engine ratings,
transmission configurations, and more for vehicles
already delivered to customers, even though those
vehicles may have been certified to a previous version
of Part 1037. This would be consistent with the EPA's
proposal to eliminate C02 standards from all model
years of vehicles—not just vehicles produced after the
EPA's new rules take effect.
40 CFR 1037.622 Shipment of partially complete
vehicles to secondary vehicle manufacturers.
Commenters suggested the EPA retain the sections
NHTSA relies on until NHTSA has the necessary
regulations in place to continue to implement their
program.
We are removing the sentence referencing GHG and
evaporative emissions from the introductory text as
proposed. We are also revising paragraph (a)(2) to
replace the reference to being excluded "from the
standards of this part under §1037.150(c)" with a
reference to being excluded "under §1037.5." We are
also removing paragraph (d)(5) that referred to GHG,
evaporative, and refueling emissions that only applied
for the EPA.
40 CFR 1037.630 Special purpose tractors.
Commenters suggested the EPA retain the sections
NHTSA relies on until NHTSA has the necessary
regulations in place to continue to implement their
program.
We are retaining the existing 1037.630.
40 CFR 1037.631 - Commenters suggested retaining
sections 1037.631(a)(1) & (2).
We are retaining 1037.631 with revisions to replace
reference to GHG standards with fuel consumption
standards and to remove the reference to Phase 3
standards.
40 CFR 1037.635 - A commenter noted the "Fire
Truck" definition was deleted in section 1037.801 but
remains as an example in subsection
1037.635(c)(1)(H).
We are retaining 1037.636 with revisions to remove
references to standards in subpart B.
We are retaining 1037.801 and the referenced
definition for "fire truck."
40 CFR 1037.645 In-use compliance with family
emission limits (FELs). Commenters suggested the
EPA retain the sections NHTSA relies on until NHTSA
has the necessary regulations in place to continue to
implement their program.
We are removing 1037.645 as proposed. It describes
how a manufacturer may change their FEL during a
model year. NHTSA does not refer to this EPA
provision and has their own provisions describing
their process.
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EPA Response
40 CFR 1037.655: Post-useful Life modifications
A commenter noted that the Language concerning
post useful vehicle modifications should be retained
to avoid higher criteria emissions on older vehicles.
We are retaining 1037.655 with revisions to remove
the reference to the Clean Air Act under 42 U.S.C.
§7522(a)(3)(A). We are also replacing the phrase "EPA
may require" with "We may require" since NHTSA
would likely be the one to request additional
information relating to these modifications. See our
revisions to the definition of "We" under 1037.801.
40 CFR 1037.660 Idle-reduction technologies
Commenters suggested that some elements of the
current language in 1037.660 should be retained to
clarify idle reduction timers, allowable override
conditions, and the definition of idle reduction system
"tamper-resistance" as preventingvehicle owners,
dealers, or other service outlets from adjusting the
threshold inactivity period.
We are retaining the existing 1037.660.
40 CFR 1037.665 Production and in-use tractor
testing. Commenters suggested the EPA retain the
sections NHTSA relies on until NHTSA has the
necessary regulations in place to continue to
implement their program.
We are removing 1037.665 as proposed. NHTSA does
not refer to this EPA provision.
40 CFR 1037.670 Optional C02 emission standards for
tractors at or above 120,000 pounds GCWR.
Commenters suggested the EPA retain the sections
NHTSA relies on until NHTSA has the necessary
regulations in place to continue to implement their
program.
We are removing 1037.670 as proposed. This
provision was added to support manufacturers
certifying to Environment and Climate Change
Canada. The EPA is no longer certifying tractors to
GHG standards referenced in this section and NHTSA
does not refer to this EPA provision.
Table 4-11 Comments related to 40 CFR 1037, subpart H
Summary of Comments
EPA Response
40 CFR 1037 subpart H - A commenter stated that the
ABT provisions of NHTSA's HD program refer to the
same provisions established in Subpart H of 40 CFR
part 1037 (e.g., 49 CFR § 535.7 (a)(2)(iv) refers directly
to sections like 40 CFR § 1037.745 the EPA proposed
to eliminate).
We are retaining the sections of 1037, subpart H, that
are referenced by NHTSA. As noted below, we are
removing provisions that are adequately covered by
NHTSA's regulations in 49 CFR 535, and we are
revising the remaining sections to remove reference to
the EPA standards.
We are retaining 1037.701,1037.725,1037.735, and
1037.740 with revisions to remove the "emission"
descriptor for references to credits and we replaced
references to the EPA standards with references to 49
CFR 535. In 1037.725, we are also removing
references to "certification" and adding a note that
1037.745 only applies for NHTSA's program. In
1037.735(e), we are also removing reference to the
Clean Air Act.
In 1037.701, we are removing paragraphs (h)-(j) that
have equivalent NHTSA provisions.
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Summary of Comments
EPA Response
We are removing as proposed 1037.705,1037.710,
1037.715, and 1037.720 that describe howto
generate credits, averaging, banking, and trading,
respectively. NHTSA has its own regulations
describing these provisions and does not reference
these EPA regulatory sections.
We are retaining 1037.745 because it is cited by
NHTSA, but we are removing "C02" from the section
heading and replacing all of the regulatory text from
that section with a reference to 49 CFR 535.7 for
provisions related to credit deficits for NHTSA's fuel
consumption credits.
We are removing 1037.750 that describes what would
happen if a manufacturer did not comply with 1037,
subpart H. the EPA would no longer be issuing
certificates and therefore would no longer be in a
position to void them.
We are retaining the existing 1037.755. Manufacturers
would continue to submit their compliance data and
information to the EPA for the NHTSA fuel efficiency
program.
Table 4-12 Comments related to 40 CFR 1037, subparts 1 and appendices
Summary of Comments
EPA Response
40 CFR 1036.801 - Commenters requested the EPA
retain several definitions for NHTSA, including Dual-
clutch transmission (DCT) and Power take-off (PTO).
A commenter recommended redefining Family
Emission Limit (FEL) since the definition refers to
Subpart H, averaging, banking, and trading credits and
emissions standards but the EPA proposed to remove
Subpart H and all emission standards.
A commenter also noted the basic vehicle frontal area
definition was deleted in section 1037.801 but
mentioned in the "Heavy-Duty Vehicle" definition.
A commenter recommended the EPA modify the
definition of model year to delete the subsection
containing the Phase 1 vehicle reference, since all
GHG references are intended to be removed from 40
CFR part 1037.
We are retaining all definitions for NHTSA with some
revisions to remove reference to C02 standards or
GHG emissions.
We are revising the definition of FCL to remove the
statement that it serves as the emission standard,
since no emission standards apply.
We are also revising the definition of FEL to replace
"greenhouse gas standards" with a reference to
NHTSA's fuel efficiency program under 49 CFR part
535 and to replace "an emission level" with "a fuel
consumption level."
We have revised the definition of model year to
remove the phrase "Phase 1" from paragraph (2).
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EPA Response
A commenter recommended redefining, and not
deleting, the definition for vocational vehicles to cover
non-tractors subject to 40 CFR part 1037.
40 CFR 1036.810 - A commenter stated that the
agency proposes removing 1037.810 which will still be
required to meet the requirements of 49 CFR part 535
and should be retained. GEM and related tools are
essential to the regulatory framework and
recommends they remain under the EPA's authority—
similar to light-duty rules—since the EPA has the
necessary expertise.
A commenter stated that any of the changes with
reference to GEM inputs and test procedures, seem to
ignore the EPA's historical role for CAFE, which has
since the advent of the CAFE program been to
determine the appropriate test procedures. It is only
natural for this role to translate into the heavy-duty
sector, regardless of whether or not the agency
maintains its HD GHG program.
We are retaining the existing 1037.810, includingthe
incorporation by reference of GEM.
Appendix A to Part 1037 — Heavy-duty Transient Test
Cycle
Appendix B to Part 1037 — Power Take-Off Test Cycle
Appendix D to Part 1037 — Heavy-duty Grade Profile
for Steady-State Test Cycles
Appendix E to Part 1037 — Power Take-Off Utility
Factors
Commenters suggested the EPA retain the sections
NHTSA relies on until NHTSA has the necessary
regulations in place to continue to implement their
program.
We are retaining all of the existing 1037 appendices.
4.3.5 Other Comments Related to the Proposed Heavy-duty Engine and
Vehicle Regulations
In this sub-section we summarize and respond to additional comments the EPA received
regardingthe proposed heavy-duty engine and vehicle engine regulations, including
comments on emissions-related warranty; Environment and Climate Change Canada's
references to the EPA heavy-duty GHG regulations; hybrid powertrain and components
testing topics; detailed comments on the GEM model, specialty vehicle hybrids, and
heavy-duty gliders.
4.3.5.1 Emission-Related Warranty
EPA Summary of Comments
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In 40 CFR 1037.120, the EPA proposed to revise the emission-related warranty
requirements revising the vehicle category descriptions of paragraph (b) in light of the
proposed removal of 40 CFR 1037.140. The EPA also proposed to remove many Phase 2
technologies from the components listed in paragraph (c), including aerodynamic
technologies, tire technologies, RESS used in hybrid vehicles, and other GHG-related
technologies. The EPA did not propose changes to warranty coverage for evaporative and
refueling components or fuel cell stacks, RESS, and other components used with battery
electric vehicles and fuel cell electric vehicles because those components could apply for
meeting the criteria pollutant emission standards.
Some commenters recommended that the EPA also remove the warranty requirements for
fuel cell stacks, RESS, and other components used with battery electric vehicles and fuel
cell electric vehicles, because they are not emissions-related systems or components if
the vehicles have zero emissions. Relatedly, in reference to credits, one commenter noted
that, under this proposal, zero emission vehicles would no longer generate emissions
credits, so failures within a warranty period would not lead to excess emissions from credit-
using vehicles.
Another commenter suggested that the EPA retain the interim provision under 40 CFR
1037.150(aa) and revise it to extend the optional warranty for components used with
battery electric vehicles and fuel cell electric vehicles. The suggested revision was to state
that it would apply for "...vehicles certified to 2024 and later standards" instead of
"...vehicles before model year 2027."
A separate commenter recommended that the EPA retain the warranty requirements for
RESS and other components used in hybrid electric vehicles, since a failure of the RESS
would increase criteria pollutant emissions for these vehicles as the engines will need to
do more work.
Some commenters recommended that the EPA retain its battery warranty and durability
requirements for RESS, battery, and powertrain components, noting that the components
play a critical role in allowing BEV and FCEV to have zero tailpipe emissions in-use and
avoiding higher criteria pollutant emissions and less effective criteria pollutant standards.
Another commenter suggested that the durability requirements will make EV repair and
maintenance more accessible for consumers and businesses, ensure that BEVs meet
quality standards similar to the broader vehicle market, and avoid worse quality BEVs
starting in MY 2027, which would reduce consumer choice and freedom by limiting viable
cost-saving clean vehicle options. Another commenter noted that these provisions are not
limited to GHGs and are not part of the GHG program.
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One commenter noted that the definition of "automatic tire inflation systems" was
referenced in 40 CFR 1037.120(d), despite the definitions of 40 CFR 1037.801 being
removed.
EPA Response
We are retaining 40 CFR 1037.140, which is used to define vehicle classes for NHTSA. As
such, we are not finalizing the proposed changes for references to the Light heavy-duty
vehicles (HDV), Medium HDV, and Heavy HDV vehicle categories in 40 CFR 1036.120(b).
We are revising as proposed the list of components covered under 40 CFR 1037.120(c).
Under this final action, emission-related warranty would continue to apply for fuel cell
stacks, RESS, and other components used with BEVs or FCEVs certifying to the EPA's
criteria pollutant standards or evaporative and refueling emission controls on vehicles
subject to the EPA's evaporative and refueling standards.
We acknowledge commenters' suggestion that warranty should not apply for vehicles with
no propulsion engine and no tailpipe emissions; however, these components are covered
under the EPA's criteria pollutant program and are out of scope for this rule. We may
consider revisions to the list of emissions-related components covered under the EPA's
warranty provisions in a future rulemaking.
We are finalizing as proposed the removal of warranty requirements for RESS and other
components used in hybrid vehicles from the vehicle provisions of 40 CFR part 1037. We
note that manufacturers certifying hybrids to the EPA's criteria pollutant program would be
doing so under the engine standards of 40 CFR part 1036. Those hybrid manufacturers
would then warrant the RESS and other components from those systems under 40 CFR
part 1036.
We are removing, as proposed, the battery durability requirements finalized underthe HD
GHG Phase 3 program. We acknowledge comments suggesting we retain the durability
requirements for the HD criteria pollutant program and may consider if such requirements
should apply for HD engines or powertrains certified to our criteria pollutant program in a
future rulemaking.
We are correcting 40 CFR 1037.120(d) to remove the example sentence that referred to
"automatic tire inflation system", which no longer applies for the EPA's emission-related
warranty. However, we note that we are retaining 1037.801 and the definition for
"automatic tire inflation system" for NHTSA's fuel efficiency program.
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4.3.5.2Environment and Climate Change Canada
EPA Summary of Comments
One manufacturer commented that Environment and Climate Change Canada (ECCC)
accepts the EPA certification and labeling for their GHG program. If the EPA were to forego
certification as outlined in 40 CFR Parts 1036 and 1037, it would double the time required
to certify, requiring certification to 49 CFR 535 and the ECCC GHG requirements
independently. Thus, it would be preferable that the EPA retain responsibility for
certification.
EPA Response
As noted in the preamble to this final action, we will not be continuing to provide the EPA
certifications for GHG emissions because we are removing the GHG emission standards in
this final action.
4.3.5.3Hybrid Powertrains and Hybrid Components
EPA Summary of Comments
One commenter, speaking on behalf of the supplier industry, requested additional
revisions to 40 CFR 1036.101, 1036.110,1036.301, and 1036.801 to clarify that the
specified requirements for OBD, powertrain testing, and selective enforcement audit
responsibilities only apply for hybrid components that are part of a manufacturer's certified
configuration.
EPA Response
The request to add clarifying language to 40 CFR 1036.101,1036.110,1036.301, and
1036.801 regarding HD hybrids and engine certification is related to the EPA's criteria
pollutant program and is out of scope for this rule. The EPA may consider additional
clarification in a future rulemaking.
4.3.5.Unrepresentative vehicle masses in GEM
EPA Summary of Comments
One commenter suggested that the EPA's proposed amendments to the provisions
containingthe EPA's GHG standards (40 CFR 1036.108), and fuel mapping procedures (40
CFR 1036.535 and 1036.540), would allow the EPA to finalize additional amendments as a
natural outgrowth of the proposal. They requested the EPA finalize amendments to address
unrepresentatively low vehicle masses in GEM for the fuel mapping of engines installed in
certain weight classes of real-world vehicles. They suggested the following:
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• 40 CFR 1036.535(a)(6) For representative testing of Light HDE installed in Light HDV
greater than 26,000 pounds GCWR and Medium HDE installed in Medium HDV
greater than 33,000 pounds GVWR or GCWR, you may multiply all steady-state fuel
map and fuel consumption at idle torque and fuel rate values by the ratio of 730 N-m
divided byTmax mapped for Light HDE and 878 N-m divided byTmax mapped for
Medium HDE.
• 40 CFR 1036.540(a)(5) For representative testing of Light HDE installed in Light HDV
greater than 26,000 pounds GCWR and Medium HDE installed in Medium HDV
greater than 33,000 pounds GVWR or GCWR, before testingyou may multiply torque
values of the new duty cycles by the ratio of Tmax mapped divided by 730 N-m for
Light HDE and Tmax mapped divided by 878 N-m for Medium HDE. Aftertesting,
divide the fuel consumption and cycle work results by the respective ratio.
EPA Response
We are finalizing as proposed the removal of the EPA's GHG standards under 40 CFR
1036.108 and are only retaining the fuel mapping test procedures to support NHTSA's fuel
efficiency program. As stated in the NPRM, we are not reopening or revising regulatory
provisions necessary for NHTSA's heavy-duty engine and vehicle fuel efficiency program.
Therefore, the requested amendments are out of scope for this rule.
4.3.5.5Specialty Vehicle Hybrids
EPA Summary of Comments
We received a comment on 40 CFR 1037.605, which allows manufacturers to use nonroad-
certified engines in certain specialty highway vehicles, though we did not propose any
changes to the provisions. The current provisions apply for up to 200 all-terrain vehicles
with specific axles, amphibious vehicles, and low speed vehicles. Through MY 2027, the
provisions also apply for up to 1,000 vehicles with a hybrid powertrain where the engine
provides energy only for the RESS. The commenter suggested that the EPA continue the
provision to allow manufacturers to make a small number of hybrid fire trucks per year after
MY 2027 due to compliance challenges associated with obtaining a highway-certified
hybrid and that the hybrid sunset was based on an expected increasing prevalence of HD
hybrid powertrains, which is not occurring.
EPA Response
We are not finalizing changes to this allowance in this final action because this request
would impact the EPA's criteria pollutant program, which is out of scope. We may consider
extending this allowance in a future rule.
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4.3.5.6Gliders
EPA Summary of Comments
A glider kit manufacturer commented in support of the EPA's rescission of the
Endangerment Finding and the GHG rules for trucks and stated that the "EPA rescission
should not be marred by doubling down on the statutory overreach in the Obama Phase 2
Rule as it relates to exceeding its statutory authority on glider kits by incorrectly finding that
they are "new motor vehicles"."
The commenter stated that the CAA does not authorize the regulation of glider kits, glider
engines, nor glider trucks as "new motor vehicles." The commenter noted that the EPA first
included gliders in its 2016 Phase 2 rule when it also included truck trailers for the first
time. The commenter stated that the D.C. Circuit Court ruled against the EPA's authority to
regulate truck trailers and that the EPA used the same arguments to justify regulating
gliders.
EPA Response
We are finalizingthe removal of any GHG emission standards that would have applied to
glider engines and glider vehicles in 40 CFR 1037.635. However, the broader issue of the
criteria pollutant standards that apply to glider engines and glider vehicles is outside of the
scope of this final action.
5 Impact Analysis Comments
The EPA received many supportive and adverse comments on the analysis presented in
Appendix B of the DRIA (draft regulatory impact analysis). We are not including this analysis
in the final action, and as we stated in the proposal, the EPA has not relied upon any aspect
ofthe DRIA, including Appendix B, orthisfinalRIAasjustification for this rulemaking. We
are not respondingto these Appendix B comments in this final action.
5.1 General Modeling and Analysis
EPA Summary of Comments
Multiple commenters reviewed the modeling results presented in the DRIA and provided
comments on modelingtools and assumptions used to generate the proposal's analysis. In
some cases, commenters refer to additional analysis they or others conducted using the
OMEGA, MOVES, and HD TRUCS models with assumptions or inputs that differed from the
EPA's proposal analysis. In other cases, comments referred to the summaries, outputs, and
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data files that the EPA provided in the DRIA and supporting materials for the proposal,
including OMEGA, MOVES, and HD TRUCS models.
Several comments were received on the topic of the EPA's modeling of sales. One
comment referred to analyses such as those by Bloomberg New Energy Finance (BNEF)
and International Council on Clean Transportation (ICCT) and observed that these more
recent BEV projections with updated Inflation Reduction Act assumptions are lower than
those made by the EPA in the 2024 LMDV rule analysis.
A commenter asserted that the EPA's DRIA departed from past practice in failing to use the
OMEGA model.
A commenter asserted that the EPA's baseline assumptions about future EV market
penetration were inflated by includingvehicles produced to comply with California's state-
level EV mandates for which the EPA had granted a waiver.
A commenter suggested that the EPA's OMEGA modeling of light- and medium-duty
vehicles should allow the removal of technologies, also known as backsliding and that
restricting the model from considering backsliding is not appropriate for the analysis of a
policy which makes requirements less stringent, or in this case, removes GHG
requirements altogether.
EPA Response
As stated in the preamble, the EPA is not relying on the Regulatory Impact Analysis (RIA). In
response to the comments that market and policy conditions have changed since the 2024
rulemakings, that the EPA failed to use the OMEGA model, and should have presented an
updated analysis forthe proposal, the EPA notes that the results of updated modeling were
summarized in the DRIA and the complete modeling inputs and outputs were provided in
the rulemaking docket.39 While the proposal did include one scenario that was based on
modeling from the 2024 rulemakings, the EPA's modelingforthe final action includes
updates such as the removal of IRA incentives and California's Advanced Clean Trucks
(ACT) policies, and lower fuel prices. As with the proposal, the analysis supporting this final
action is based on an updated analysis that was conducted usingthe OMEGA, HD TRUCS,
and MOVES models. Seethe RIA for this final action for a more detailed discussion of the
updates to the EPA's analysis.40
39 Kevin Bolon, Memorandum to Docket EPA-HQ-OAR-2025-0194."Appendix A Supporting Materials for
Analysis Using 2024 LMDV and HDP3 Rule Methodologies" Available online:
https://wvwv.regulations.gov/document/EPA-HO-OAR-2025-0194-0Q38.
40 "Rescission of the Greenhouse Gas Endangerment Finding and Motor Vehicle Greenhouse Gas Emission
Standards Under the Clean Air Act Regulatory Impact Analysis." EPA-420-R-26-002. February 2026.
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In response to comments that the EPA's baseline assumptions were inappropriate (for
example, by not accurately accounting for California's ZEV policies), the EPA notes that for
both the proposal and final action analyses, only policies for which the EPA had granted a
final waiver were included. Specifically, since the California Advanced Clean Cars II (ACCII)
BEV requirement waiver was not finalized, there were no ACCII BEV's incorporated into the
OMEGA baseline for the 2024 LMDV rule, for the proposal, or for this final action's analysis.
Regarding the ACT waiver which had been finalized and later disapproved, the ACT-
associated medium- and heavy-duty BEVs were included in OMEGA, HDTRUCS, and
MOVES forthe 2024 rules, but not included for the proposal and final action analyses.
In response to the comment about modeled BEV projections, for this final action analysis
the EPA has updated the consumer assumptions in the OMEGA model to account for lower
anticipated consumer demand for BEVs, consistent with the recent third-party projections
referenced by the commenter.
The EPA's responses to comments on specific modeling assumptions for technology costs,
IRA treatment, consumer valuation of fuel savings, and fuel prices are provided in the rest
of section 5.
Several commenters noted that the EPA's approach to modeling the proposed removal of
GHG standards for light- and medium-duty vehicles by holding the modelyear2026 GHG
standards constant was not appropriate and did not capture the full magnitude of the
impacts. In response, we have updated the OMEGA model's action case to use per vehicle
GHG footprint and work factor targets of 999 grams C02 per mile for model years 2027 and
later as a more realistic representation of the removal of all GHG requirements. As part of
this updated modeling, we also changed the OMEGA model's settings to enable the
consideration of technology backsliding, which allows manufacturers to remove GHG-
reducing technologies that do not pay back for the consumer in fuel savings within 2.5
years.
5.2 Fuel Prices
5.2.1 Gasoline and Diesel Prices
EPA Summary of Comments
The EPA received many comments related to the price of gasoline and diesel that the EPA
assumed for the DRIA. Many commenters suggested the EPA should have used fuel prices
from Energy Information Administration's (EIA) Annual Energy Outlook (AEO) 2025, instead
of the prices from AEO 2023 that were assumed in the analysis. Some commenters stated
that the EPA should have used prices from the Alternative Transportation case in AEO 2025,
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pointing out that the Alternative Transportation case shows that gasoline and diesel prices
increase with the removal of the GHG standards. Commenters pointed out additional
research supporting the results of higher liquid fuels prices consistent with the
assumptions in the Alternative Transportation case.
Some commenters also noted concern with the EPA's low fuel price scenario in the DRIA.
These commenters stated that the EPA approach of reducing the AEO 2023 Reference case
gasoline price by $1.00 and reducingthe diesel price by $0.25 was wrong, unrealistic, and
unsupported. Commenters stated that these prices are inconsistent with historical
evidence on supply-side effect on global prices; that domestic actions are unlikely to lead
to large global oil supply impacts, especially in the medium- to long-run.
Commenters also stated that the EPA should complete both higher and lower fuel price
sensitivities, not just estimate the impact lower fuel prices have on the analysis.
EPA Response
For the final action, we no longer use gasoline or diesel prices from AEO 2023, or the
estimated lower prices ($1.00 for gasoline and $0.25 for diesel) assumed in the analysis for
the proposed rule. The analysis forthe final action uses gasoline and diesel prices from
AEO 2025. We present two fuel price scenarios using fuels prices from, or derived from, the
AEO 2025 Reference case, the AEO 2025 Alternative Transportation case, and the AEO
2025 Low Oil Price case. See the Regulatory Impact Analysis for this final action for more
information.
We do not provide a higher fuel price scenario because we believe that the AEO 2025 High
Oil Price scenario does not include the full range of impacts of other actions of this
Administration that could lead to further reductions in the price of fuel.
5.2.2 Electricity Prices
EPA Summary of Comments
Commenters noted that the modeling done for the proposed rule does not reflect the
appropriate electricity prices. Specifically, some commenters stated that the proposal
implies that electricity prices are expected to increase, however, that does not follow
previous modeling or real-world data, which indicate that EVs will put downward pressure
on electricity rates. For example, some commenters stated that as demand for electricity
from EVs increases and more units of electricity are sold, the per-unit cost of improved
utilization of existing and new infrastructure falls, with commenters noting that the
downward pressure on electricity prices from increased consumption would offset the
increased costs of infrastructure as demand from higher volumes of EV increases. In
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addition, commenters stated that many EV owners charge at night, during lower marginal
cost hours, which results in increasing sales without proportionally increasing costs.
Commenters also noted that there was no new analysis to support the electricity prices
assumed in the proposal. Some commenters completed their own analysis of the EPA's
proposed rule and some of those analyses assumed alternative electricity prices, including
the prices from the No IRA case from AEO 2023, as that was the most recent AEO case that
excludes the IRA. Commenters noted that the EPA neglects electric vehicles' ability to put
downward pressure on electricity rates, and that the power sector analysis in LMDV and HD
GHG Phase 3 rules showed that retail electric rates can decrease as a result of managed
charging.
Some commenters stated that the electricity prices assumed in the analysis for the
proposed rule were underestimated, and that underestimation grows over time, as the EPA
assumed prices decrease while commenters state that prices are expected to increase.
Commenters also stated that the EPA's assumed depot charging costs in the proposal are
not attainable in most utility service areas. Commenters state that ZEV commercial and
public charging rates are higher than the EPA assumed in the proposal, with electricity rates
projected to continue to rise. Commenters state that these increases are expected in part
due to growth in demand from data centers planned to service artificial intelligence (Al)
systems and other emerging energy intensive technologies.
Commenters note that, counterto the proposal, in the LMDV and HD GHG Phase 3 rules
explicitly the EPA described how the impact of the rules on the power system and retail
electricity rate were determined, accounting for both the need to build additional power
generation units and transmission at the bulk level and the need to build additional
electrical infrastructure at the distribution level.
EPA Response
For the final action, we updated the estimated electricity prices used in the proposal to
prices estimated in AEO 2025, which are slightly higher than those used in the proposal.
We updated the electricity prices used in the final action to the AEO estimates to reflect the
most up-to-date and supported current and expected prices available. We present two fuel
price scenarios using prices, including electricity prices, from the AEO 2025 Reference
case, the AEO 2025 Alternative Transportation case and the AEO 2025 Low Oil Price case.
See the Regulatory Impact Analysis for this final action for more information.
5.3 Consumer Valuation of Fuel Costs
EPA Summary of Comments
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Many commenters criticize the EPA's treatment of how consumers value improved fuel
economy in the DRIA. Several commenters state that the DRIA provided an incomplete,
misleading representation and interpretation of the literature on fuel economy valuation -
missing some studies and misinterpretingthe payback period implications of others.
Some commenters focus on the assumptions that the EPA employs in the OMEGA
modeling of light-duty vehicle purchase decisions pertaining to this issue. Consistent with
the modeling performed for the 2024 rule, the EPA assumed consumers internalize the first
2.5 years of fuel savings in their purchase decisions and imposed an assumption that
vehicle performance is held constant {i.e., the potential to enhance performance even
further in lieu of investing in fuel economy is not accounted for). Some commenters argue
that the EPA should instead more explicitly model any potential tradeoffs (or synergies)
between fuel economy improving attributes and other vehicle attributes in the OMEGA
modeling.
Many other commenters focus on how the projected change in fuel expenditures resulting
from the rule are then valued in the calculation of the net monetized impact of the rule. In
particular, the commenters do not support the approach taken in the DRIA to only
incorporate the first 2.5 years of changes in fuel expenditures in the calculation of
disbenefits. Several commenters state that even if the agency continues to impose a
specific assumption regarding consumer valuation of fuel economy in its modeling of
consumer purchase decisions and manufacturer decisions, the EPA should include the full
value of future changes in fuel expenditures in the calculation of net monetized impact of
the rule. Commenters state the 2.5-year assumption in this part of the analysis is
unexplained and unsupported by the wide range of estimates in the published literature.
Some commenters argue that the EPA should assume closer to full valuation; others argue
that the EPA should assume substantial undervaluation. At least one commenter suggests
sensitivity analysis around this assumption given the lack of consensus in the literature.
Several commenters note that tradeoffs between fuel costs and other attributes likely differ
for BEVs compared to conventional vehicles, and the literature cited in the DRIA largely
excludes EVs. Commenters argue that the value(s) chosen should reflect potential
differences between BEVs compared to ICE) vehicles.
Several commenters point out that it is inappropriate to apply the 2.5-year assumption to
heavy-duty vehicles.
EPA Responses
The EPA agrees that there continues to be a lack of consensus in the published academic
literature on the extent to which consumers value fuel economy improvements in their
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vehicle purchase decisions. Consensus of the definitive underlying reasons for estimates
of undervaluation has not been reached either. We updated the literature review in the final
Regulatory Impact Analysis (RIA) by reviewing additional studies pointed out by
commenters, and we reevaluated our interpretations of the originally included studies for
accuracy and consistency. The expanded list of panel studies included in the final RIA
discussion widens the range of estimates of the proportion of future fuel costs internalized
in car and light truck purchase prices by consumers. We continue to find that the study
estimates are sensitive to the datasets, time horizons, and identifying variation employed,
and our review does not support selecting a single study or value over others. The revised
discussion in the final RIA concludes that the reviewed empirical literature suggests that
consumers may undervalue future fuel cost savings from more stringent standards, though
there is not a consensus on the magnitude of this effect.
In the modeling of consumer purchase decisions and manufacturer production choices,
the EPA has continued to use a 2.5-yearvaluation period in the modelingforthe final
action. The reviewed literature suggests that a 2.5-year valuation is on the low end of the
range of estimates in recent panel studies. As the literature review does not support
selection of any single study or estimate over others, and the 2.5-year period is within the
range of estimates from this literature, the EPA continues to use this value in the final RIA.
Our review of the literature and the wide range of results also supports commenter
recommendations on the usefulness of sensitivity analyses to demonstrate how the
impacts of the rule may vary under different consumer and manufacturer valuation
assumptions. For this final action, in addition to the 2.5-yearvaluation assumption, the
EPA also presents scenarios assumingfull consumer valuation. These two scenarios
represent a wide range of plausible consumer undervaluation of fuel cost savings. The EPA
views the range of results presented in the RIA as a form of sensitivity analysis, or a
bounding exercise, on the importance of this assumption in the analysis for LD, MD and HD
vehicles.
The EPA agrees that tradeoffs among attributes likely differ between EVs and ICE vehicles
and acknowledges this potential modeling issue in the final RIA. There is little literature on
how consumers value fuel expenditures relative to other attributes for EVs due to the
recent entry of EVs in the market and relatively low market penetration until recent model
years. Further, early EV adopters may have very different preferences than other
consumers, exacerbating the difficulty in studying this topic. The EPA will continue to
assess the literature in this area to better incorporate any differential EV and ICE vehicle
valuations in the future.
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5.4 Inflation Reduction Act Tax Incentives
EPA Summary of Comments
Commenters noted that the OBBBA included several changes to the tax incentives related
to the purchasing, leasing, and manufacturing of EVs and associated electric vehicle
supply equipment (EVSE) installations. Commenters noted that the EPA incorrectly
removed the IRA's 45X tax credits from the DRIA analysis because this advanced
manufacturing tax credit for EV batteries tax credit was not removed in the OBBBA and
instead was modified. Commenters noted that the tax incentives removed in the OBBBA
will likely decrease the affordability of EVs. Another commenter noted that the EPA
estimated that ZEV sales without the C02 standards would approach one-third of total
sales by 2035, but that estimate assumed the tax credits for new and used ZEV purchases
and home charging stations would remain available to reduce the cost to consumers, and
the tax incentives for manufacturers would help reduce the list price of new vehicles that
have now been repealed.
Other commenters noted the EPA's DRIA analysis projected that all EV batteries will be
produced domestically by 2030 or 2032 and will meet all the requirements to qualify for
100% of the 45X production tax credit. The commenters stated that this was an
unreasonable assumption because it does not match the marketplace's supply-chain
reality of how OEMs source EV batteries.
Commenters also noted that the DRIA analysis did not take into consideration state and
local incentives to reduce the upfront costs of EVs, which may offset the loss of the federal
tax incentives. Commenters provided examples of states that provide EV tax credits,
including but not limited to California, Kansas, Maryland, Oregon, New Jersey, New York,
and Washington.
EPA Response
In Appendix A.2 of the DRIA, the EPA estimated the impact of rescinding GHG standards
with all the IRA tax credits and the California ACT program removed. For the DRIA analysis,
we removed the following IRA tax credits after 2025: the credits for purchasing (30D) and
leasing (45W) LD and MD BEVs, battery production tax credits (45X) for LD, MD and HD
BEVs and HD FCEVs, vehicle purchase tax credits (45W) for HD BEVs and HD FCEVs, and
the tax credit for EVSE installation (30C) for HD BEVs. The DRIA analysis had some overlap
with actions recently signed into law in the OBBBA.
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As discussed in RIA AppendixA accompanying this final action, we reflect the actions
signed into law in the OBBBA.41 Specifically, we removed the following IRA tax credits after
2025: the credits for purchasing (30D) and leasing (45W) LD and MD BEVs, vehicle
purchase tax credits (45W) for HD BEVs and HD FCEVs, and the tax credit for EV supply
equipment (EVSE) installation (30C) for HD BEVs. We also revised the phase-out of the
advanced manufacturing production credit (45X) to reflect 75% in 2031, 50% in 2032, 25%
in 2033, 0% in 2034 and later.
For the final action RIA, we did not revise our projections for the percent of EV batteries that
qualify for the 45X tax credit in 2027 through 2032. We continued to use the Department of
Energy (DOE) analysis that shows in 2027-2032 there will be sufficient domestic battery
manufacturing capacity for the LD and HD industries to produce cells and modules that
meet the requirements of this tax credit and to supply the volumes we project in this final
action.42 Consistent with our approach for the 2024 LMDV rule's analysis, we did not apply
a further cost reduction to represent the 10 percent electrode active material credits under
45X or the 10 percent critical mineral production credits that does not phase out overtime.
It may be the case that some manufacturers choose to not utilize or establish domestic
battery manufacturing capacity, for example, due to business considerations for a low-
volume model. However, because some elements of 45X are not included in our analysis,
the EPA does not believe we have generally overestimated the average value of 45X credits.
We did not quantitatively include other incentives such as state and local incentives for
EVs in our final action RIA analysis. To the extent that these incentives do affect vehicle
price, our vehicle costs to consumers may be slightly overstated; however, as a societal
cost, those costs would be subsumed by taxpayers.
5.5 Vehicle Technology Costs
EPA Summary of Comments
Some commenters stated that battery costs and EV costs are lower than the EPA predicted
in the 2024 rules, even with the elimination of the EV tax credit. One commenter stated that
research shows that the average battery prices are likely to fall nearly 50 percent from 2023
to 2026. Another commenter noted that lithium-ion battery costs have already fallen 24%
41 One Big Beautiful Bill (July 4, 2025). See Sections 70502, 70503, 70504, 70514,
https://wvwv.congress.gOv/biU/119th-congress/house-biU/1/text.
42 Kevin Knehr, Joseph Kubal, Shabbir Ahmed, "Cost Analysis and Projections for U.S.-Manufactured
Automotive Lithium-ion Batteries", Argonne National Laboratory report ANL/CSE-24/1 for US Department of
Energy (Jan. 2024), available at https://www.osti.gov/biblio/2280913. See pp.16-19 and Appendix A6.
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below the 2024 Multipollutant Rule's battery cost projections.43 In addition, a commenter
noted that BNEF reported that globally at the end of 2024 that battery prices had the
biggest annual drop in prices since 2017—reaching $115/ kWh. For EVs specifically, the
price of batteries was below $100/ kWh at $97/ kWh for the first time. Goldman Sachs
predicts that global average battery pack prices will reach $80/ kWh by 2026, driven in part
by new battery technologies, such as lithium iron phosphate ("LFP") batteries, which are
expected to increase.44 With respect to hybrid vehicles, one commenter stated that the EPA
overestimated hybrid vehicle prices by nearly $1,400. These commenters noted that by
overstating the EV technology costs, the EPA overstated the saved technology costs of
removing the GHG standards in the DRIA.
However, other commenters noted that the current prices for EVs are higher than for
comparable ICE vehicles or that manufacturers are losingtens of thousands of dollars on
every EV. One commenter stated that Ford spent an average of $119,083 per electric
vehicle it sold, compared to only $31,871 per conventional vehicle.45
Commenters noted that the EPA assigned all of the technology costs projected in the 2024
LMDV rule to the GHG standards (costs associated with both GHG and criteria pollutant
standards) in the Appendix A analysis in the DRIA. They noted this is inconsistent with
maintaining the PM standards and because the EPA did not include the gasoline particulate
filter costs in the action case where criteria pollutant standards remain in place, the EPA's
analysis in the DRIA overstates the cost savings attributable to repealing only the GHG
program.
EPA Response
Although some commenters believe the EV costs used in the analyses for the 2024 rules
and the DRIA for this rule are too low, others believe the EV costs used by the EPA are too
high. We note that the comments focused on current EV vehicle prices, which reflect
current vehicles and not vehicles during the 2027 and beyond timeframe, do not reflect the
impact of learning and higher production levels. The EPA did not conduct a new cost
analysis of vehicle technologies for this final action RIA. Instead, we used the values from
the 2024 LMDV and HD GHG Phase 3 rules but updated the costs to reflect 2024$.
43 Comments submitted by Attorneys General of Massachusetts, et.al.EPA-HQ-OAR-2025-0194-
13587.GiUingham-Jenn 8.
44 Comments submitted by Natural Resources Defense Council.EPA-HQ-OAR-2025-0194-2608.
45 Comments submitted by American Free Enterprise Chamber of Commerce, the Illinois Corn Growers
Association, and the Missouri Corn Growers Association.EPA-HQ-OAR-2025-0194-1498.See Ford Motor Co.,
Form 10-Q, 2023 Q1.
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In the proposal, our analysis assumed the complete revocation of the 2024 LMDV and HD
GHG Phase 3 rules. This meant that we were unable to account forthe continuation of the
non-GHG standards that were finalized in the 2024 LMDV rule. The analysis for this final
action has been updated to partially account for the continuation of those non-GHG
standards. Specifically, we have added the cost of gasoline particulate filters back into the
case without the GHG standards. This has the effect of reducing the cost savings of the
final action compared to the proposal (all other things being held equal).
EPA Summary of Comments
One commenter raised concerns related to the costs, reliability and availability of hydrogen
and natural gas alternatives for HD vehicles. As the EPA itself noted in its GHG Phase 3
proposal, projections for hydrogen storage costs vary dramatically—from as high as $1,289
per kilogram to $375 per kilogram of usable hydrogen by 2025—raising significant
uncertainty about the long-term affordability of this fuel. The EPA further acknowledged
that the hydrogen market is still in its infancy, with business models ranging from
negotiated contracts to "turnkey" fleet solutions.
Today in 2025, hydrogen fuel cost is four and a half times higher per mile than a gasoline
hybrid and three times higher than that of a conventional gasoline vehicle. To be
competitive with hybrid gasoline vehicles on a per-mile basis, according to Stillwater
Associates, hydrogen would need to be priced at $5.88/kg. For comparison, hydrogen has
retailed at $32.94/kg in 2025 year-to-date.
Importantly, the EPA stated in the GHG Phase 3 proposal, "the hydrogen infrastructure is
expected to need additional time to further develop... but we expect the refueling needs
can be met by MY 2030," (emphasis added). Two years later in 2025, the commenter has
not seen evidence that the trucking industry's hydrogen refueling needs will be met in 2030.
The current infrastructure shortfall is stark: according to the U.S. Energy Information
Administration, there are only 60 hydrogen fueling stations in the United States, exclusively
located in California. This limited network is profoundly insufficient to support national
deployment, especially in meeting the aggressive targets outlined in GHG Phase 3
standards.
Although natural gas can be considered as another viable fueling alternative, infrastructure
limitations further constrain natural gas adoption as well. America's tank truck industry
requires widespread, reliable access to fueling options to maintain safe and efficient bulk
commodity transportation.
EPA Response
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The EPA agrees that the infrastructure related to hydrogen is currently extremely limited
and would require significant buildout to meet the potential demand for hydrogen trucks to
operate across the United States. Additionally, the EPA agrees that this would result in
increasing the savings from this rulemaking. The EPA has not fully incorporated this issue
into the Final Regulatory Impact Analysis.
5.6 OMEGA and HD TRUCS Modeling Compliance
In the modelingthe EPA conducted forthe DRIA, the EPA noted that the LD and HD
modeling scenarios projected noncompliance in some or all of the years using the OMEGA
and HD TRUCS tools. The EPA also noted in the DRIA that our modeling did not account for
all possible manufacturer compliance strategies which firms may adopt to ensure
compliance with the vehicle GHG standards.
EPA Summary of Comments
Commenters noted that the EPA's modeling of LD vehicles in 2032 in the DRIA does not
show that the program is infeasible, since there are additional flexibilities for modeling
credit banking and product planning which avoids earlier expired credits.
Commenters noted that the EPA developed HD TRUCS to inform the stringency of setting
GHG emission standards and not to predict compliance with the GHG standards.
Commenters highlighted new research that identified several technology packages for ICE
vehicles that manufacturers could use to achieve compliance with the Phase 3 standards
without selling as many EVs.
EPA Response
The EPA conducted new analyses for the final action for LD, MD, and HD vehicles which
incorporated updated fuel prices and the IRA tax incentive changes made in the OBBBA,
among other changes outlined in Appendix A of the final action RIA. In response to
comments about the modeled compliance status for light-duty vehicles in the OMEGA
results, we note that the updated modeling for this final action shows full compliance in
every year for the No Action case where GHG standards remain in place. We continue to
note in the appendix that the results of the OMEGA and HD TRUCS runs represent only one
technology path. As we stated in the DRIA, it is important to note that our modeling does
not account for all possible manufacturer compliance strategies which firms may adopt to
ensure compliance with the vehicle GHG standards, includingtechnology packages
highlighted by commenters or the use of credits. This rule removes all GHG standards and
we are not using either modeling tool to inform a different stringency level. We are using the
models to inform the technology and operating costs associated with the No Action case,
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where the GHG standards remain in place, and an Action case where the chosen modeling
assumptions represent a scenario where all GHG standards are removed, to assess the
overall economic impacts of the rule to satisfy the requirements in E.0.12866.
5.7 Consumer Topics
EPA Summary of Comments
Commenters had a range of views on the topic of how GHG standards, or the removal of
them, will impact vehicle options available to consumers, with some commenters
highlighting that GHG standards, and leaving them in place, will increase vehicle choice for
consumers and introduce new efficient, low emitting, and cheaper vehicle options, while
other commenters noted that leaving the standards in place will reduce vehicle choice and
eliminate cheaper, higher-emitting, or ICE vehicle models, or would force consumers to
purchase an EV even if they didn't want to.
Commenters stated that the standards have already increased consumer choice by
growing the diversity of powertrain types. Commenters cited research that generally
indicated GHG standards do not limit vehicle choice, and research indicatingthat states
adopting clean car standards have more vehicle models available than states without the
standards without a decrease in ICE vehicle availability. Commenters also stated that the
EPA provided no support indicating GHG standards reduce vehicle choice, or that repealing
them will make vehicles available at lower prices.
Commenters also had a range of views on consumer demand for EVs, with some
commenters saying that EV demand has increased since the promulgation of the LMDV
and HD GHG Phase 3 rules, while others said EV demand has fallen, makingthe standards
infeasible. Others stated that the EPA projections of BEV demand in the LMDV and HD GHG
Phase 3 rules were overstated, unrealistic, and unsupported.
Some commenters say that EV and hybrid sales have increased in recent years for LD, MD,
and HD vehicles, and the surveys mentioned in the proposed rule's DRIA saying that EV
sales are falling or stagnant are contradicted by real-world sales data which indicate that
consumer demand for new vehicles appears unaffected by vehicle standards.
Commenters say that some of the initial issues affecting consumer acceptance of EVs are
being phased out as substantial progress in EV charging infrastructure is made, battery
production costs are falling, and EV range and performance are increasing. Commenters
also say that that consumers who purchase a BEV tend to retain the technology overtime.
One commenter provided data showing Tesla sales rebounded quickly after the company
hit the threshold that triggered the phase-out of the first generation EV tax credits tax credit
phase-out.
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With respect to the EPA projections of HD vehicle BEV demand, commenters stated that
previously the EPA analyses overlooked the unsuitability of EVs for long-haul freight
transport, citing issues with previous the EPA assumptions surrounding refueling
infrastructure and charging time, payload, range, cost and more. Commenters stated that
the complexity and customization of many vocational configurations was not accounted
for or adequately addressed in the HD GHG Phase 3 estimations of ZEV acceptance. Some
commenters noted that the cost of batteries was not appropriately accounted for in the HD
GHG Phase 3 rule, with battery price assumptions not reflecting actual market conditions.
Commenters stated that HD ZEV adoption is unlikely given the recent actions to void the
California ACT regulation, poor market conditions, and adverse impacts of ZEVs not
reaching cost parity with conventional counterparts. Commenters also stated that FCEVS
would provide a better solution than BEVs, but that the development of refueling
infrastructure is limited. Other commenters said that the payback analysis completed by
the EPA in HD GHG Phase 3 was faulty and overestimated market adoption of HD ZEVs.
Some commenters iterating that EV demand has fallen mention changes in government
policy, including removing the IRA tax incentives leading to more expensive EVs, the slow
buildout of charging infrastructure, and increasing electricity prices and falling gasoline
prices as some of the reasons for depressed EV markets. Additionally, commenters said
that the assumptions from the previous rules do not reflect industry realities, and
regulations based on these assumptions risk limiting consumer options and putting
excessive pressure on manufacturers to fundamentally alter markets without
commensurate consumer interest. Commenters stated that many OEMs have walked back
their previous statement announcing electrification efforts in LD, MD, and HD markets,
with HD manufacturers stating that the market is not mature enough to support the HD
GHG P3 standards and other commenters citing uncertainty related to the ZEV technology
as being a concern.
Some commenters stated that the LMDV and HD GHG Phase 3 standards are not feasible
without cross-subsidization, which a commenter claimed was not considered in the LMDV
rule. Another comment stated that the cross-subsidization needed to support the level of
EVs needed to meet the LMDV standards would increase as more EVs and fewer ICE
vehicles are sold, and that this, as well as increasing costs from purchasing credits,
increasingfines, and/orthe cost to build out an EV production line to demonstrate
compliance would increase both the price of EVs and ICE vehicles.
Commenters state that in order to meet the LMDV and HD GHG Phase 3 standards, the EPA
would have to force consumers to purchase BEVs, which are more expensive to purchase
and maintain. Commenters state that forcing automakers to develop ideas or expedite
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progress to meet nonexistent consumer demand distorts market realities and costs
manufacturers more resources, which in turn costs consumers. Commenters state that
the standards are technology-forcing, would reduce the number of available vehicle
models for consumers, and would be more expensive for consumers.
Commenters stated that prior EPA analyses ignored consumer preference for ICE vehicles,
disregarded market signals on purchase decisions, and instead insisted consumers do not
know what is good for them. Commenters said that this instance on market failure is
inappropriate to consider when analyzingthe cost of the regulation. Other commenters
cited research indicatingthat emissions, fuel efficiency, and impact on climate are
significant factors when purchasing a car, with fuel efficiency ranking higher than
improvement in performance attributes. A commenter additionally indicated that survey
results indicate producers have not been voluntarily respondingto consumer demand for
increased fuel efficiency.
Commenters had opposingviews on how GHG standards affect vehicle affordability, with
some saying standards lead to reduced affordability, constraining access to new vehicles,
especially for lower- and middle-income households. Commenters stated that if vehicle
prices were lower, the number of vehicles on the road would not increase but that
scrappage, and increased fleet turnover, would be the dominant effect, supporting
environmental progress. Other commenters stated that leaving the GHG standards in place
will increase vehicle affordability and lower operating costs, which would be especially
beneficial for businesses and lower- and middle-income households. Some commenters
stated that the potential for HD EVs to lower freight costs can lead to a lower cost of living.
Commenters reiterated the EPA findings from the LMDV and HD GHG Phase 3 rules that the
standards would reduce operating costs for consumers, and that this reduction in
operating costs would more than offset the increase in upfront cost, even without the IRA
tax incentives. They also stated that upfront EV cost continues to fall relative to ICE
vehicles.
Some commenters state the removing the standards will lead to higher vehicle ownership
costs and a less efficient vehicle fleet, with some commenters noting that the availability of
vehicle options may differ by region, resulting in a market where consumers in some states
have access to more technologically advanced and efficient vehicles than in others.
Some commenters support solutions to reduce emissions from transportation, though
some of those commenters also state that the LMDV and HD GHG Phase 3 timelines were
unrealistic.
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Comments received on the topic of the EPA's modeling of consumer choice included
suggestions for how the EPA could improve their modeling. One commenter suggested that
the EPA should use a consumer model that includes convenience and otherfactors to
assess consumer interest and purchase trends, in addition to upfront purchase cost.
Other commenters said that the EPA changed position on consumer choice in this
proposalfrom statements and analyses prepared forthe LMDV and HD GHG Phase 3 final
rules without acknowledging the changed position. Some examples provided include
changing from the position that the 2024 rules were performance based and did not require
particular technologies to meet the standards compared to characterizing the previous
standards as electric vehicle mandates in the proposal; not explaining purchaser costs
details to the extent they were detailed in the 2024 rules; changing position on EVs and
GHG regulations providing consumer choice and failingto provide an explanation or
analysis to support the changed position similar to the 2024 rules' consumer/purchaser
acceptance analyses.
Commenters requested that the EPA document and thoroughly explain how more recent
information, reduced supportive policies, and updated projections demonstrate that the
standards as promulgated in the LMDV and HD GHG Phase 3 rules are not achievable and
to explicitly state that if GHG standards were to be retained or reinstated, they would need
to be revised to meet the requirements of CAA.
EPA Response
The EPA acknowledges these comments regarding consumer topics, and the EPA has a
discussion of a number of these issues in the RIA for this final action. However, as
described in the Executive Summary of the final action preamble, and throughout the final
action preamble, the EPA is finalizingthis action based on the proper interpretation of its
CAA authority, and the issues raised by commenters are not applicable to the arguments in
the final action.
5.8 Social Cost of Greenhouse Gases
EPA Summary of Comments
Many commenters support the continued use of the Social Cost of Greenhous Gas (SC-
GHG) metric in the EPA's regulatory analyses. Commenters stated that the comprehensive
peer-reviewed economics literature supports a robust value forthe SC-GHG and that
ignoringthe economic toll of climate impacts defies rigorous economic analysis.
Commenters claimed that the EPA erred by omitting the cost of increased GHG emissions
from the proposed rule's cost-benefit analysis. They said that such an omission fails to fully
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account for the societal costs of the proposed repeal and undermines the legal basis for
withdrawing the Endangerment Finding and the associated proposal to repeal the vehicle
GHG rules, and that a failure to adequately explain the decision to ignore the net societal
harms of the proposal was arbitrary and capricious.
Comments regarding the presence of uncertainty in SC-GHG estimates stated that
uncertainty is primarily due to high-end risks, suggesting that actual climate damages
could be much higher than current estimates. Commenters further stated that claims that
climate damages are too uncertain to value disregard the rigorous methods SC-GHG
estimates use to quantitatively account for uncertainty.
Commenters also submitted research that found the macroeconomic damages from
climate change are larger than previously thought.
Regarding the Department of Energy's (DOE) report, "A Critical Review of Impacts of
Greenhouse Gas Emissions on the U.S. Climate," commenters were critical of the report's
review of the relevant economics literature and conclusions related to the estimation and
application of SC-GHG values and provided specific, detailed critiques of the report.
Commenters concluded that if the DOE report is invoked by the EPA to justify omitting SC-
GHG considerations from its regulatory decisions, it would represent an inadequate and
legally vulnerable basis for doing so.
For further comments related to climate science and the DOE report, see RTC section 3.1.
Several commenters were critical of SC-GHGs and related methodologies used by the EPA
and other governmental bodies. Commenters claimed that climate benefits, like those
estimated in the 2024 LMDV rule, were illusory and not related to any real effects on
climate phenomena - even significant reductions in U.S. motor-vehicle emissions would
have negligible effects on global temperatures. Commenters questioned the justification of
past regulatory actions based on modeled benefits that are below the threshold of
detectability. They claimed that use of SC-GHG values leads to exaggerated regulatory
benefits.
Other commenters claimed that changes to the magnitude of SC-GHG over time illustrates
why they cannot serve as a stable or objective foundation for regulation. Commenters
stated that when the value depends more on modeling assumptions than on observable
data, the claimed benefits of regulation rest on numbers too uncertain to guide decisions.
Commenters claimed that the climate models used to derive the SC-GHG values overstate
temperature records and impacts, and rely more on assumptions than observable data,
leading to inflated estimates. Specifically, commenters criticized the use of the
Representative Concentration Pathway 8.5 (RCP8.5), labeling it as an extreme and
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unrealistic emissions scenario. Commenters claimed that the EPA's continued reliance on
this trajectory is a mark against scientific integrity.
Commenters also claimed that the SC-GHG estimates used in the 2024 LMDV rule were
derived using artificially low discount rates. Higher discount rates, aligned with Office of
Management and Budget (OMB) guidance, would significantly reduce the SC-GHG values.
Commenters also criticized using the global effects of GHG concentrations in SC-GHG
calculations, claiming these effects are largely borne by non-U.S. residents and are
minimally affected by U.S. policies.
Some commenters claimed that rising C02 concentrations have unacknowledged benefits,
such as enhancing crop yields due to C02 fertilization and C02-induced warming.
Commenters said that, as a result, any detrimental effects of warming are partially offset
by these benefits. Commenters also state that past SC-GHG estimates rely too heavily on
pessimistic projections of agricultural damages from climate warming.
One commenter asserted that the federal government calculation of the SC-GHG is driven
primarily by the inclusion of "co-benefits" in the form of reductions in criteria and
hazardous air pollutants already regulated by the EPA. According to this commenter, SC-
GHG estimates include "co-benefits" to generate significant "benefits" from GHG policies,
particularly for the health benefits of reductions in the emissions of fine particulates
(PM2.5).
For further comments related to climate science, see RTC section 3.1.
EPA Response
The EPA acknowledges these comments regarding the EPA's use of the SC-GHG metric.
However, as described in the Executive Summary of the final action preamble, and
throughout the final action preamble, the EPA is finalizing this action based on the proper
interpretation of its CAA authority, and the issues raised by commenters are not applicable
to the arguments in the final action.
On January 20, 2025, PresidentTrump issued Executive Order (E.O.) 14154, "Unleashing
American Energy" which, along with other actions, withdrew earlier guidance on
calculating the social cost of carbon {i.e., the monetized impacts of emissions of GHGs)
and directed the EPA to issue guidance on assessingthe impacts of GHG emissions in
regulatory analysis.46 In response to that direction, the Office of Management and Budget
(OMB) issued Memorandum M-25-27 on May 5, 2025, providing current guidance on the
46 90 FR 8353 (Jan. 29, 2025), "UnleashingAmerican Energy."
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consideration of GHGs in regulatory decision-making.47 That Memorandum directed
agencies not to quantify or monetize the impacts of GHG emissions, except to the extent
required by law, "because the uncertainties in performing monetized impacts
quantifications are too great." The EPA agrees with Memorandum M-25-27 that it is
inappropriate to utilize the SCC due to the significant uncertainties.
The EPA is aware of no statute that it administers that requires the quantification or
monetization of GHG impacts. Accordingly, the EPA will not monetize such impacts while
Memorandum M-25-27 remains in effect.
For the EPA's response to comments on the DOE Report, see RTC section 3.1. For the EPA's
response to comments on climate science topics, see RTC section 3.1.
5.9 Employment and Domestic Production
EPA Summary of Comments
We received a variety of comments related to the impact of the proposed rule on
employment and on U.S. competitiveness on a global scale.
Commenters stated there have already been major investments and job creation related to
clean energy, includingvehicle manufacturing, EV battery manufacturing, and charging
infrastructure, and removingthe Endangerment Finding and the vehicle GHG standards as
proposed leads to regulatory uncertainty, disrupts long-term planning, and puts at risk
current and planned investments and jobs in manufacturing, supply chain and related
industries. Commenters stated that aggressive decarbonization targets, strong minimum
standards, and GHG regulations will create new industries and jobs, as well as provide
significant positive impacts on labor markets. Some commenters noted that reducing GHG
emissions and reducingthe impact of climate change will continue to lead to significant
benefits including increased employment. Some commenters noted that the jobs being
created are generally expected to be high-quality, high-paying jobs. Commenters stated
that removing the GHG standards will lead to job loss, as well as negative impacts on
geographic availability of jobs and on replacement jobs that are comparable in terms of
benefits and pay to the jobs that will be lost. Some commenters cited research that shows
jobs lost in manufacturing will only be marginally offset by increases in fossil fuel
exploration, extraction and refining.
Other commenters stated that the Endangerment Finding and the current GHG standards
have stifled job growth and leaving them in place threatens jobs in the auto manufacturing
47 https://www.whitehouse.gov/wp-content/upLoads/2025/Q2/M-25-27-Guidance-lmpLementing-Section-6-
of-Executive-Qrder-14154-EntitLed-UnLeashing-American-Energy.pdf. and posted in the docket for this ruLe.
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and aftermarket business and will also have significant impacts on upstream and
downstream markets like the petroleum industry and gas stations. Commenters noted that
keepingthe GHG standards will lead to negative impacts on geographic availability of jobs
and expressed concern about the availability of replacement jobs that are comparable in
terms of benefits and pay to the jobs that will be lost. Commenters state that repealing
these rules will lead to increased domestic production and job growth, and that energy
policies putting America first and expanding domestic oil and gas development will lead to
advanced, well-paying manufacturing jobs.
Other commenters noted that revising instead of removing the GHG standards will support
domestic manufacturing and domestic job growth. Commenters stated that updates to
make the standards technology neutral, accurately accountingfor all available technology
and promoting biofuels (like biomethane) will support job growth, including promoting rural
jobs.
Some commenters noted that the EPA failed to acknowledge, consider, or estimate the
impacts of the proposed rule on employment.
Some commenters said that strong standards should be paired with robust investments to
onshore clean vehicle production, which will support ongoing domestic job creation and
global competitiveness in automotive and related industries, including in the EV battery
industry. Commenters also stated that the Endangerment Finding and the GHG standards
have supported strong global competitiveness in auto manufacturing and related
industries. They said that the proposed rule will lead to U.S. products becoming less
marketable on a global scale, which will induce layoffs for auto workers; others noted that
the rule will make it harder to compete globally in EVs, which is likely to benefit
manufacturing competitors overseas at the expense of domestic jobs. Commenters also
noted that jobs that shift overseas are not likely to return to the U.S. Commenters noted
that tailpipe GHG standards will still exist in international markets if the standards are
removed in the U.S., and there is a risk of employers producing emission control
technologies closer to the markets they are deployed, which will reduce domestic jobs and
investments. Commenters stated that without similar standards to those in internation
markets, U.S. auto and battery manufacturing will fall behind technically and become less
competitive.
Some commenters noted that the EPA failed to consider the impacts of the proposed rule
on global competitiveness.
Other commenters stated that this proposal incentivizes the use of cheap fossil fuel energy
sources, providing the U.S. a comparative advantage. Commenters say that the finalized
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proposal will allow the U.S. to strengthen its competition with other nations that do not
have GHG rules by increasing domestic manufacturing.
EPA Response
While there may be some impacts on employment or domestic production due to the
removal of the EPA's GHG standards, as described in the Executive Summary of the final
action preamble and throughout the final action preamble, the EPA is finalizing this action
based on the proper interpretation of its CAA authority, and the issues raised by
commenters are not applicable to the arguments in the final action and are out of scope of
this final action. However, the EPA remains concerned with assertions that EV mandates
result in better results for automobile workers. Additionally, we support reshoring our
automobile industry but disagree that this regulation will negatively impact our ability to
onshore more automotive-related activities and believe that this could result in increased
reshoring due to the fact that EVs can require six times the critical minerals than internal
combustion engine vehicles. Additionally, please see the final RIAfor a discussion of
potential employment impacts.
5.10 Grid Reliability and Related Topics
EPA Summary of Comments
Some commenters stated that the EPA's proposal would increase grid instability in electric
power sector, while other commenters noted that LMDV and HD GHG Phase 3 rules
increase grid instability.
Commenters noted that the EPA performed detailed resource adequacy analyses for the
LMDV and HD GHG Phase 3 rules, which assessed the combined impact of increasing
demand for electricity from data centers and other sources with the demand for electric
vehicles arising from the 2024 rules, and found that the power sector could meet all
resource adequacy requirements. They noted that the stringency of the resource adequacy
scenarios considered in the LMDV and HD GHG Phase 3 rules exceeds those of the
forecasts of the Energy Information Agency and North American Electric Reliability
Corporation (NERC).
Commenters disagreed with the EPA's claim that rescinding the LMDV and HD GHG Phase
3 rules will materially reduce electric power demand, or that this reduction will help to
materially improve grid reliability, since the electric load associated with electric vehicle
charging is an order of magnitude less than the electric load associated with data centers.
Commenters noted that the EPA's electric power sector analysis for the proposal fails to
consider the value provided by vehicle electrification for Vehicle Grid Integration, voltage
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control, frequency regulation, peak load reduction, managed charging, etc., all of which
has been shown to bolster grid stability. Co mm enters noted that the EPA's proposal did not
examine the traditional electric power sector metrics, such as resource adequacy,
operational reliability, peak load, or other related grid impacts, like transmission capacity
and congestion, as had the LMDV and HD GHG Phase 3 rules. Commenters noted that
there is nothing provided in the proposal that justifies invalidating the EPA's the prior
conclusion that the power sector is capable of reliably integrating additional electricity
demand due to the LMDV and HD GHG Phase 3 rules. Further, these commenters noted
that nothing in the proposal provides any evidence that this has changed since the LMDV
and HDGHG Phase3 rules were finalized, northatthe proposed rollback of vehicle
emission standards would confer significant benefits to the electric grid. Commenters
noted that electric power sector stability can be affected by the retirement of baseload
generation and the lack of sufficient intermittent generation, that reliable sources of
electric power generation should be added to the energy mix, and that replacing
dispatchable generating resources with intermittent resources may require backup
generation and storage.
Commenters noted that the 2025 DOE Resource Adequacy Report (used in the proposal by
the EPA) rests on fundamentally flawed assumptions regarding load growth, retirements,
capacity additions, etc., and that it was often contradicted by the expert opinions of the
Energy Information Administration and NERC.
Commenters noted that the electric power sector is overloaded, antiquated, vulnerable,
challenged and/or shows signs of stress, and that the need for electric power sector
upgrades predates vehicle electrification, and is exacerbated by building electrification,
industrial load, population growth, and data centers.
EPA Response
The EPA acknowledges these comments related to grid reliability and adequacy. However,
as described in the Executive Summary of the final action preamble, and throughout the
final action preamble, the EPA is finalizing this action based on the proper interpretation of
its CAA authority, and the issues raised by commenters are not applicable to the
arguments in the final action. The EPA considers these comments out of scope of this
rulemaking and takes no position on the merits of the comments.
5.11 Emissions Inventories and Health Impacts
EPA Summary of Comments
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Commenters stated that the EPA failed to quantify, monetize, or consider the GHG, criteria
pollutant, air toxics emission impacts or public health impacts of removing the GHG
standards in the DRIA Appendix A. They noted that the EPA has consistently evaluated and
monetized certain benefits in past rulemakings. Commenters stated that the GHG, criteria,
and toxics emission impacts resultingfrom the proposed rulemaking are readily
quantifiable. For example, in the 2024 Rules, commenters noted that the EPA projected
cumulative GHG emissions reductions of 8.2 billion metric tons carbon dioxide equivalent
(C02e). Another commenter noted in their review of a memorandum in the docket that the
Agency projected GHG emission impacts, but did not considerthem in the proposal in
either the preamble or the DRIA.
A commenter stated that the EPA may revise CAA section 202(a)(1) standards only by
exercising its judgment "in accordance with the provisions of this section." They concluded
that the EPA must demonstrate that it made rational technical and policy judgments
regarding statutory factors such as emissions impacts, technological feasibility, lead-time,
and costs of compliance. They noted that the absence of the emissions impacts in the
technical analysis is in contrast to prior rules, such as the 2024 rules. They also stated that
the EPA failed to acknowledge or explain its choice to abandon prior methodologies for
quantifying GHG emissions impacts from the 2024 Rules, rendering its change in position
arbitrary and capricious.
Some commenters conducted their own analyses of the emission impacts related to the
removal of the EPA's GHG standards. They found that the proposal would increase air
pollution and GHG emissions and have associated negative health impacts.
EPA Response
The EPA acknowledges these comments regarding the EPA's consideration of GHG, criteria
pollutant, airtoxics emission impacts and public health impacts of removingthe GHG
standards. For this final action, the EPA is including in the docket a memorandum
summarizing the impacts on projected inventories of criteria pollutants, airtoxics, and
GHG emissions.48 As described in the Executive Summary of the final action preamble, and
throughout the final action preamble, the EPA is finalizing this action based on the proper
interpretation of its CAA authority, and the issues raised by commenters are not applicable
to the arguments in the final action. The EPA considers these comments out of scope for
this rulemaking.
48 Memorandum to Docket EPA-HQ-OAR-2025-0194, "Projected Criteria, Air Toxics, and GHG Emissions
Impacts for the "Rescission of the Greenhouse Gas Endangerment Finding and Motor Vehicle Greenhouse
Gas Emission Standards Under the Clean Air Act" Final Rule."
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For transparency purposes, the EPA provides quantified emissions impacts within the final
action docket. Additionally, as stated within the RIA and technical support documents, the
EPA does not believe it is appropriate to monetize emissions that have significant
uncertainties related to them.
5.12 Benefit-Cost Analysis Topics
EPA Summary of Comments
A commenter stated that the EPA's net benefits analyses failed to monetize GHG impacts,
despite the Agency's history of monetizing such impacts, the existence of well-established
methodologies for doing so, and the relevance of emissions reductions as a statutory
factor and the statute's primary purpose. Commenters also stated that the EPA failed to
monetize any public health impacts at all in DRIA Appendix A. They stated that the EPA's
failure to monetize the emissions benefits of its proposed rule renders its cost-benefits
analysis arbitrary and capricious.
Some commenters conducted their own assessments of the impacts on the removal of the
GHG standards and found that the GHG standards continue to provide net benefits for
society.
A commenter stated that the EPA is required to analyze the combined effects of concurrent
actions (such as the EPA's other deregulatory actions) in the baseline and make these
available for comment. They further state that the EPA's failure to perform and disclose an
analysis of the cumulative effects is arbitrary and capricious.
Commenters suggested that the EPA's use of three and seven percent discount rates are
inconsistent with recent economic evidence that supports retaining the two percent
discount rate used in the 2024 rules, or even lower. They suggest that the EPA should use
the latest version of OMB Circular A-4 issued in November 2023, even though it was
rescinded by OMB this year, which includes the use of a two percent discount rate.
A commenter suggested the withdrawal of the EPA's Technical Documentation on the
Framework for Evaluating Damages and Impacts and associated documents.
EPA Response
As we stated in the proposal, the EPA has not relied upon any aspect of the DRIA or this
final RIA as justification forthis rulemaking. The EPA is repealingthe GHG emission
standards for light-duty vehicles, medium-duty vehicles, heavy-duty vehicles, and heavy-
duty engines consistent with the discussion of legal authority in the final action preamble.
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Please see additional responses to the monetization of GHG emissions in section 0 of this
document.
With respect to not monetizing emissions from criteria air pollutants, hazardous air
pollutants, or GHGs, as explained within the final action, the uncertainty related to how the
emissions would result in monetized impacts is too great to appropriately monetize.
However, the EPA has quantified the emission impacts and provided them within the
docket.
Regarding the EPA's Technical Documentation on the Framework for Evaluating Damages
and Impacts and associated documents, this is out of scope for this final action.
In the EPA's benefit and cost assessments, we included the impact of concurrent actions
such as the OBBBA, California waiver rescissions, and the E.O. on energy dominance in
how we model our projected fuel prices and the treatment of ACT. However, we do not
include impacts of other rules and regulations that have not been finalized.
With respect to the comments on the EPA's use of three and seven percent discount rates,
we continue to present the results in the final RIA with the three and seven percent
discount rates. Our approach is pursuant with OMB's revocation of the Office of
Management and Budget Circular A-4 of November 9, 2023, and reinstatement of the
Office of Management and Budget Circular A-4 of September 17, 2003 (Regulatory
Analysis).49
EPA Summary of Comments
Commenters raised methodological concerns related to DRIA Appendix B. Specifically, a
commenter stated that the methods were unjustified, and the data was outdated.
Additionally, commenters stated that credit prices have fallen substantially since 2016.
Some commenters were supportive of the EPA's benefit cost analysis and noted that a
revealed preference analysis reflecting market economics properly reflected the best
available peer-reviewed methods available. Commenters noted this represented a positive
shift away from past flawed analyses which misapplied methods from behavior welfare
economics.
EPA Response
49 Executive Office of the President, Office of Management and Budget, Memorandum M-25-15 Recission and
Reinstatement of Circular A-4 (Feb. 12, 2025), available at https://www.whitehouse.gov/wp-
content/uploads/2025/03/M-25-15-Recission-and-Reinstatement-of-Circular-A-4.pdf.
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As we stated in the proposal, the EPA has not relied upon any aspect of the DRIA or this
final RIA as justification forthis rulemaking. The EPA is repealingthe GHG emission
standards for light-duty vehicles, medium-duty vehicles, heavy-duty vehicles, and heavy-
duty engines consistent with the discussion of legal authority in the final action preamble.
However, based on the significant feedback on DRIA Appendix B on the methodology and
use of outdated data, the EPA is not finalizing Appendix B as part of this final action.
5.13 National Security
EPA Summary of Comments
Commenters state that the EPA did not consider national security, including the impacts on
net imports of oil, critical minerals, and metals used in battery production, in the proposal
forthis rule. Finalizingthe rule as proposed will increase the risks of climate change, and
the impact of climate change impacts national security, including increasing risks to
military infrastructure, threats to domestic food and water security, and increasing the
demand for diplomatic, economic, humanitarian, and military resources.
Other commenters say that the proposal supports the use of domestically fueled vehicles,
promoting national security. Commenters state that finalizing the rule as proposed will
increase U.S. reliance on fossil fuels, which will increase national security through
increased gross domestic product (GDP).
Commenters say that the EPA has not considered the loss of significant energy security
benefits orthe impacts on U.S. energy independence in this proposal. Commenters state
that the removal of incentives for a transition to EVs and domestic battery production will
increase U.S. reliance on imported oil and critical minerals, increasing energy and mineral
security risks.
One commenter stated that the EPA's energy security analysis in the DRIA is based on
outdated data.
Some commented that this proposal will allow the utilization of already owned U.S. natural
resources to increase the production of oil, natural gas, and coal, ensuring energy
independence and energy dominance.
EPA Response
The EPA acknowledges the comments regarding national security as it relates to risks to
military infrastructure, threats to domestic food and water security, and increasing the
demand for diplomatic, economic, humanitarian, and military resources. However, as
described in the Executive Summary of the final action preamble, and throughout the final
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action preamble, the EPA is finalizingthis action based on the proper interpretation of its
CAA authority, and the issues raised by commenters are not applicable to the arguments in
the final action. The EPA considers these comments out of scope of the rulemaking.
In response to comments regarding national security as it relates to the impacts on net
imports of oil, critical minerals, and metals used in battery production, we include the
estimated impact of this rule on these "energy security" factors in RIA Appendix A. The
energy security analysis performed forthe final action uses the same assumptions as
those used forthe LMDV50 and HD GHG Phase 351 rules finalized by the EPA in 2024. Forthe
reasons discussed in the final action preamble, the agency did not rely on energy security
impacts as a basis for our decision in this final action.
For the EPA's response to the impact of this regulation on climate change, see RTC section
3.1.
6 Statutory, Executive Order, and Procedural
Requirements
6.1 Executive Order 12866: Regulatory Planning and Review and
Executive Order 14094: Modernizing Regulatory Review
EPA Summary of Comments
Commenters stated that the EPA's inclusion of net benefits solely in the EO 12866
preamble section, its disclaimer against reliance on the RIA, as well as the lack of mention
of net benefits in any of the proposal's rationales, indicates the agency has abandoned
consideration of net benefits in its rulemaking, despite the agency's history of doing so and
the relevance of net benefits. They stated that the EPA has failed to explain this change in
position, rendering its proposal arbitrary and capricious.
EPA Response
As we stated in the proposal, the EPA has not relied upon any aspect of the DRIA or this
final RIA as justification for this rulemaking. Commenters suggested that the benefit-cost
assessments provided in the DRIA do not justify repealing the prior standards. However,
the EPAis repealing the GHG emission standardsfor light-duty vehicles, medium-duty
50 89 FR 27842 (Apr. 18, 2024) "Multi-Pollutant Emissions Standards for Model Years 2027 and Later Light-
Duty and Medium-Duty Vehicles."
51 89 FR 29440 (Apr. 22, 2024) "Greenhouse Gas Emissions Standards for Heavy-Duty Vehicles-Phase 3."
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vehicles, heavy-duty vehicles, and heavy-duty engines consistent with the discussion of
legal authority in the final action preamble, and the EPA is not relying upon the CAA section
202(a) factors for standard-setting in this final action. For this final action, we have
conducted benefit-cost assessments pursuant to E.0.12866, but we recognize that there
are costs and benefits that we are currently unable to fully quantify and monetize.
6.2 Paperwork Reduction Act (PRA)
EPA Summary of Comments
The EPA received comments on the Paperwork Reduction Act (PRA) and Information
Collection Request (ICR) supporting document. One commenter insisted that the costs to
states from revising their State Implementation Plans (SIPs) as a result of the rule must be
counted in the PRA analysis. Another commenter stated that the EPA's estimations of zero
hours and $0 costs is flawed because it undercounts respondents, and it fails to take into
account reviewing and revising policies and procedures and training. Specifically, the
commenter stated that the EPA failed to include costs and burdens from business and
market disruption resulting from revokingthe Endangerment Finding, GHG emission
standards, and associated test procedures. They stated that affected party's counsel or
compliance officer would be required to review and revise all policies and procedures to
comply with regulatory changes and train teams up and down the supply chain of these
changes. The commenter also stated that the estimated respondent numbers are
undercounted and need to be revealed more transparently.
EPA Response
The ICR Supporting Document estimates the burden associated with assembling and
providing information to the EPA for our regulatory purposes. In this case, the data is
needed to certify engines and vehicles to our national emissions control standards.
Therefore, the only respondents are companies and individuals who certify engines and
vehicles in certain industrial sectors (provided in North American Industry Classification
System (NAICS) codes), and the estimated reporting burden is for acquiring, assembling,
and reporting the relevant data to obtain an EPA Certificate of Conformity.
In the proposed rule, the EPA prepared revised Information Collection Request supporting
documents for three previous rules that would be affected by the proposal: LMDV,52 HD
GHG Phase 3,53 and HD programmatic54 ICRs. We are revising the data reporting
52 EPA ICR No.2750.03, revising EPA ICR 2750.02 (OMB 2060-0764).
53 EPA ICR No.2734.03, revising EPA ICR 2734.02 (OMB 2060-0753).
54 EPA ICR No.1684.22, revising EPA ICR 1684.21 (OMB 2060-0287).
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requirements to reflect rescinding the motor vehicle GHG requirements. The other criteria
pollutant requirements remain the same.
The number or identities of the respondents for these ICRs would not change because
engine and vehicle manufacturers continue to be required to comply with the EPA's criteria
pollutant emission standards and NHTSA's CAFE and HD fuel efficiency standards.
The estimated information collection reporting costs include review and revision of
certification procedures. Affected companies and individuals are not required to consider
other costs not relevant to the reporting, including any costs associated with potential
supply chain or market disruptions - which would be speculative.
We provided 3 tables of information collection reporting costs in the RIA:
• Initial ICR costs, from the 3 previous rules
• Amount of the change
• Final ICR costs for the revised ICRs, removing the costs of the GHG program.
The analyses reflect the following:
• For LMDV: Criteria pollutant costs remain; as proposed, we added back in savings
associated with reduced burden for reduced number of ICE certifications. 35
companies were affected; 35 remain because these companies certify other
vehicles and engines; taking out costs and savings associated with the GHG
program.
• For HD GHG Phase 3: Program is eliminated: $0 costs. We are removing all
certification reporting burdens for this rule; all of the certification requirements for
that rule are rescinded.
• For HD Programmatic ICR: We are withdrawing the proposed edits to this ICR as
they are no longer needed. As explained elsewhere, we did not propose and are not
changing elements of the regulations that are necessary for programs unrelated to
the GHG emission standards, including emission standards for criteria pollutants.
We are revising our proposal to remove all of the GHG-related regulations and,
instead, are retaining the EPA's regulations and information collection activities that
are needed to support the vehicle standards administered by NHTSA. However, the
EPA will not be issuing certificates for GHG emissions for motor vehicles and
engines on the basis of these regulations.
Finally, states are not included in the ICR because they do not certify vehicles or engines to
emission standards, or report to the EPA under our vehicle and engine emission control
programs.
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6.3 Regulatory Flexibility Act (RFA)
EPA Summary of Comments
The EPA received comments from several entities and individuals with respect to our
Regulatory Flexibility Analysis (RFA) and proposal to certify that this action will not have a
significant economic impact on a substantial number of small entities.
These commenters generally focused on potential impacts of the proposed rule on small
businesses that would not be directly regulated by the proposed rescission, including
everyone affected by climate change; small automotive part manufacturers; small
industrial and other facilities; small businesses generally; and small truck owners and
operators.
One commenter suggested the EPA did not adequately consider increased purchase prices
forvehicles as a costto small businesses. In addition, another commenter suggested that
the EPA made two errors in its regulatory flexibility analysis: first, assuming the analysis
must consider only adverse impacts; and second, assuming deregulatory actions do not
have adverse impacts. Regarding deregulatory actions, the commenter noted specifically
the adverse impacts on small businesses that produce the parts necessary for future cars
to meet the emissions limits set in the standards, including lost revenues from producing
and sellingthose parts to vehicle and engine manufacturers. They recommended the EPA
halt the action and carry out a new regulatory flexibility analysis as they prescribe.
Another commenter noted that the EPA did not considerthe impacts of the rule on small
electric vehicle manufacturers, such as Slate or Telo, which benefit from the market
demand created by the regulatory requirements.
EPA Response
Our assessment of small business impacts prepared to support the EPA's certification that
the rule will not have a significant economic impact on a substantial number of small
entities was appropriately limited to small entities that would be regulated under the
rulemaking {i.e., engine and vehicle manufacturers).
The EPA noted that, similar to large engine and vehicle manufacturers, small engine and
vehicle manufacturers are expected to have reduced regulatory compliance costs because
the revised regulations remove the certification requirements for electric vehicles. The
purpose of the EPA's vehicle and engine emission control programs is not to create or
maintain a particular set of market characteristics, favor any individual firm(s), or try to
change or maintain relative market shares. Small engine or vehicle manufacturers, such as
Slate or Telo, may continue to produce and market vehicles of their choice, including
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electric vehicles. The reduced certification costs may make their vehicles more
competitive, potentially increasing their shares of the electric vehicle market.
Other than engine and vehicle manufacturers, the rule does not impose any requirements
on small businesses (.e.g., small truckingfirms and small part manufacturers, including
those that produce parts necessary for future cars to meet emission limits, are not
regulated entities under the final action's requirements in that they are not required to
certify their products or report information to the EPA). The impacts on small businesses to
which the commenters refer would not be effects of the rule on regulated entities and thus
are not impacts that we are required to analyze. See Cement Kiln Recycling Coal. v. EPA,
255 F.3d 855, 869 (D.C. Cir. 2001) (noting that "this court has consistently rejected the
contention that the RFA applies to small businesses indirectly affected by the regulation of
other entities"), Mid-Tex Elec. Coop. v. FERC, 773 F.2d 327, 342-43 (D.C. Cir. 1985) ("An
agency may properly certify that no regulatory flexibility analysis is necessary when it
determines that the rule will not have a significant economic impact on a substantial
number of small entities that are subject to the requirements of the rule. Congress did not
intend to require that every agency consider every indirect effect that any regulation might
have on small businesses in any stratum of the national economy."); see also Coalition for
Responsible Regulation v. EPA, 684 F. 3d 102, 129 (D.C. Cir. 2012).
Though the EPA is not required to consider non-regulated entities such as purchasers and
operators of fleets or trucks, or parts manufacturers in our Regulatory Flexibility Act
analysis since they are not regulated entities underthe rule, we do consider concerns
about purchaser costs as well as other concerns about infrastructure and refueling and
charging facilities. As noted elsewhere, there are about 14 million Schedule C businesses
that own at least one vehicle, with most of those owning two or more. With 285 million
vehicles registered nationwide, about 10 percent of those vehicles, if not more, are owned
by small businesses. Additional vehicles are owned by non-profits and small for-profit
businesses that do not file Schedule C. The savings to these businesses will be substantial,
as discussed in chapter 6 of the RIA.
6.4 Unfunded Mandates Reform Act (UMRA)
EPA Summary of Comments
Commenters stated that the removal of the GHG standards would cause regional
noncompliance with the National Ambient Air Quality Standards (NAAQS) for sulfur oxides
(SOx), nitrogen oxides (NOx), particulate matter (PM), and indirectly ozone. This will lead to
additional costs for small governments and trigger the requirement for the EPA to conduct
a special assessment and consultation process underthe Unfunded Mandates Reform Act.
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Similarly, Tribes would be impacted and would bear costs associated with their own
regulation of GHG emissions.
EPA Response
The EPA acknowledges these comments related to the potential for regional
noncompliance with the NAAQS. This action does not contain an unfunded mandate of
$100 million (adjusted annually for inflation) or more (in 1995 dollars) as described in
UMRA, 2 U.S.C. § 1531-1538, and does not significantly or uniquely affect small
governments. The action imposes no enforceable duty on any state, local, orTribal
governments, and relieves duties with respect to the private sector.
6.5 Tribal-Related Comments
EPA Summary of Comments
We received comments from 25 Tribes and stakeholder groups that represent Tribal
interests. Of the Tribes that commented, two were located in EPA Region 5, one each from
Regions 6 and 8, and the rest were from Region 10, including many from Alaska.
All Tribes that commented expressed opposition to the EPA proposal to rescind the GHG
Endangerment Finding. Some stated that the EPA's presumption that the rule would not
result in substantial direct impacts to Tribal communities were foundational^ flawed.
Tribes cited concerns with climate change impacts, including warming temperatures,
changes in forests and fisheries, increases in extreme heat, severe and persistent drought,
ice coverage (lakes), frequency and intensity of storms and flooding, changes to the timing
of seasons, changes to the water cycle, reductions in surface and groundwater,
deterioration of water quality, diminished forage amount and quality, increases in wildfire
frequency and intensity, diminished crop yields, animal migration, animal populations
(which ensure food security), increased pressure from pests and pathogens, and impacts
to mental, physical, and public health. Many Tribes noted that clean air is a right that is
protected underTribal treaty rights. Some Tribes expressed concern over air pollution and
respiratory disease from tailpipe emissions and exposure to vehicle traffic from highways
nearTribal land. They noted that indigenous peoples across the U.S. have a higher
prevalence of asthma and other respiratory ailments as compared to other ethnic groups.
Some Tribes mention economic concern with impacts on carbon credit markets and other
industries that rely on the Endangerment Finding decision, like state-mandated
compliance markets in Washington and California, and other voluntary markets.
Tribes from Alaska specifically noted concerns with coastal erosion, water contamination,
impacts to fisheries, melting tundra and permafrost, an altered jet stream, food insecurity
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(hunting, fishing, foraging), wastewater management from permafrost thaw, infrastructure
degradation, and other events that are felt more frequently at higher northern latitudes,
including the need for some entire communities to relocate due to severe climate impacts
on their communities.
Stakeholder groups expressed concerns with the EPA's Tribal Consultation process and
exclusion of meaningful commitment to Tribal sovereignty, trust responsibility, and
reserved rights. Comments from stakeholder letters echo many concerns highlighted in
Tribal comments, particularly disproportionate impacts on disadvantaged communities,
environmental justice concerns, concerns on preserving cultural properties, historical
properties, and sacred sites, higher rates of unemployment and poverty, higher risk of
developing cancer and other chronic health and reproductive issues due to
disproportionate exposure to pollutants, limited access to healthcare, cumulative impacts
from historical and ongoing environmental degradation, loss of intangible cultural heritage,
indigenous knowledges, and traditional lifeways.
EPA Response
The EPA acknowledges the Tribes' comments on the potential impacts of the proposed
Reconsideration of 2009 Endangerment Finding and the Greenhouse Gas Vehicle
Standards. The Agency also recognizes that Tribal treaty rights constitute Federal law.
However, Tribal treaty rights do not expand Congress's grant of authority to the Agency
under the CAA. As described in the Executive Summary of the final action preamble, and
throughout the final action preamble, the EPA is finalizing this action based on the proper
interpretation of its CAA authority. The EPA finds that the final action is supported by and
consistent with the CAA, relevant case law, and the U.S. Constitution
We note that, consistent with the EPA Policy on Consultation with Indian Tribes, the EPA
invited Tribal leaders and designated consultation representatives to participate in the
Tribal consultation and coordination process. The EPA consulted with Tribal officials from
the Nez Perce Nation, Confederated Tribes of Grand Ronde, Snoqualmie Tribe, and Pueblo
of San Felipe during the development of this action.
6.6 Executive Order 13045: Protection of Children from Environmental
Health Risks and Safety Risks
EPA Summary of Comments
Commenters noted that in the EO 13045 section of the preamble for the proposed rule, the
EPA states that "At this time, the EPA does not believe that the proposed action would have
a material adverse impact on the health of individuals with respect to non-GHG air
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pollutants, including on children, because the EPA anticipates that the impacts of
repealing GHG emission regulations would have only marginal and incidental impacts on
the emission of non-GHG air pollutants. Potential health impacts of such air pollutants will
continue to be controlled through direct emissions limits and a number of other programs
that target regional and national air quality, including the NAAQS program."
Commenters say that there is no documentation for the analysis of impacts on emissions
of non-GHG pollutants; for example, commenters note that in the DRIA the EPA estimates
that by increasing PM emissions the proposed action would lead to annual monetized
health costs but does not provide documentation for those numbers.
In addition, a commenter states that the allegation that air pollutants will be controlled
through direct emission limits and other programs that target regional and national air
quality, including the NAAQS program, is unsupported by any analysis and contradicts the
agency's previous analyses.
EPA Response
The EPA acknowledges the comments regarding children's health. However, as described
in the Executive Summary of the final action preamble, and throughout the final action
preamble, the EPA is finalizing this action based on the proper interpretation of its CAA
authority, and the issues raised by commenters are not applicable to the arguments in the
final action. Additionally, as stated within the preamble, although the GHG emissions at
issue in this rulemaking do not have direct impacts on human health, we acknowledge the
possibility that this action could impact emissions of criteria pollutants and airtoxics.
Children are not expected to experience greater ambient concentrations of air pollutants
than the general population. Additionally, as discussed in the preamble, there are safety
benefits from this final action that would benefit children as they are more susceptible to
grievous injuries from less safe motor vehicles.
We note that, as explained above, this action would not impact separate emission
standards for criteria pollutants by the EPA or separate standards set by NHTSA. At this
time, the EPA does not believe that the action would have a material adverse impact on the
health of individuals with respect to non-GHG air pollutants, including on children,
because the EPA anticipates that the impacts of repealing GHG emission regulations
would have only marginal and incidental impacts on the emission of non-GHG air
pollutants. Potential health impacts of such air pollutants will continue to be controlled
through direct emission limits and several other programs that target regional and national
air quality, includingthe NAAQS program.
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6.7 Use of Artificial Intelligence for the Final Action
EPA Summary of Comments
Several commenters stated their objection to the EPA using any artificial intelligence (Al)
tools in working through the public comments to prepare the final action. Other
commenters noted that if Al is used in the formulation of the final action, the EPA should be
clear where and how Al was used.
EPA Response
We did not use artificial intelligence to assist in draftingthe proposal, summarizing
comments, formulating responses to the comments, or making decisions forthe final
action.
6.8 Federalism
EPA Summary of Comments
Commenters stated that the EPA's proposal to repeal federal mobile source standards
represents a departure from the cooperative federalism principles that underpin the CAA
and would undermine the partnership between federal, state, and local agencies that has
been essential to achieving air quality improvements over recent decades. Commenters
stated that the CAA establishes a framework of shared responsibility, with the EPA setting
national standards and providingtechnical and financial support, while state and local
agencies implement programs tailored to local conditions and needs. They also noted that
mobile sources travel across state and local boundaries, making coordinated federal
regulation important for achieving comprehensive emission reductions.
Commenters said that cooperative federalism framework depends on regulatory certainty
and predictability to enable effective long-term planning by state and local agencies,
regulated industries, and affected communities. They remarked that SIPs, regulatory
development processes, and compliance strategies require stable federal regulatory
frameworks to operate effectively. Commenters also stated that states rely on the EPA to
reduce emissions from vehicles to support meetingthe NAAQS requirements, and without
reductions from vehicles, states must reduce emissions from stationary sources or
develop burdensome regulations of consumer products. They said that it is critical that the
vehicle sector does its part to reduce pollution, and it is the EPA's responsibility to ensure
these reductions. Commenters claimed that with the EPA's proposal, it is clear that the
federal government is abandoning its long-standing legal obligations, leaving the states and
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their citizens increasingly vulnerable to the devastating and costly impacts of climate
change.
Another commenter stated that rescinding the 2009 Endangerment Finding55 is a positive
step toward bringing federal policy closer to that of competitive federalism, allowing for
greater innovation and experimentation in mitigating energy and climate issues. They
stated that this system places federal policy back onto the path of its proper role: creating
healthy competition between state institutions.
EPA Response
The EPA acknowledges the comments regarding potential impacts on states. However, as
described in the Executive Summary of the final action preamble, and throughout the final
action preamble, the EPA is finalizingthis action based on the proper interpretation of its
CAA authority, and the issues raised by commenters are not applicable to the arguments in
the final action. While we do not believe we need to respond to these comments, we
disagree with the premise that this is counter to cooperative federalism as this does not
change any underlying authority between the federal government and the state with
respect to the CAA.
6.9 National Environmental Policy Act (NEPA)
EPA Summary of Comments
A commenter stated that the EPA failed to meetthe NEPA which requires federal agencies
to assess the environmental effects of proposed actions prior to making decisions and to
provide opportunities for public review and comment on those evaluations. They stated
that the EPA failed to evaluate the health and environmental impacts of the proposal and
failed to document the loss in criteria pollutant benefits, and the proposal would be very
harmful based on the EPA's regulatory documents.
EPA Response
Section 7(c) of the Energy Supply and Environmental Coordination Act of 1974 (15 U.S.C. §
793(c)(1)) exempts all EPA actions under the CAA from the requirements of NEPA.
Furthermore, forthis final action, the EPA has performed modelingto estimate changes in
criteria pollutants, air toxics, and GHG emissions. The projected emissions changes can be
55 "Endangerment and Cause or Contribute Finding for Greenhouse Gases Under Section 202(a) of the Clean
Air Act,"74 FR 66496 (Dec. 15, 2009) (Endangerment Finding).
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found in a memorandum in the docket for this action.56 As described in the Executive
Summary of the final action preamble, and throughout the final action preamble, the EPA is
finalizing this action based on the proper interpretation of its CAA authority, and the issues
raised by commenters are not applicable to the arguments in the final action.
6.10 Procedural Requirements
EPA Summary of Comments
A commenter suggested that the EPA be prepared to issue an interim final rule (IFR) in
accordance with APA Section 553(b)(B) to delay the HD GHG Phase 3 and the MY 2027
Phase 2 GHG emission standards in response to any stay of the final action or other
adverse court ruling in this matter. Similarly, another commenter suggested the EPA issue
an IFR to set temporary GHG standards for light- and medium-duty vehicles based on a
recent model year and reinstate for MY 2027 and later alternative GHG targets for small
volume manufacturers.
Commenters stated that the EPA is obligated under APA and the CAA to consider
alternatives and a commenter suggested that the EPA should consider an alternative of
postponing the proposed repeal until after the reconsideration of the Endangerment
Finding and any challenges to it are concluded. Another commenter stated that the EPA did
not docket information relevant to the proposal. They state the following items are missing
such as: internal and external agency communications relevant to the NPRM, as well as
communications with the White House and external political and industry stakeholders.
The commenter also stated the "EPA also failed to provide as part of this rulemaking
fundamental information in the economic impact analysis required under Clean Air Act
section 317.42 U.S.C. § 7617(a)(5), (d) (requiringan economic impact assessment for all
section 202 vehicle rules that is as extensive as practicable)." They also stated that the EPA
did not make available data regarding the cumulative impacts analysis underlying its draft
RIA. The commenter also stated that the EPA must provide an opportunity to comment on
items that are not a logical outgrowth of the proposal.
A commenter stated that the EPA and other federal agencies removed information related
to GHG emissions, climate change, and human health from websites and that this made it
more difficult to review the scientific record on climate change and health.
A commenter stated that the EPA had made statements indicating it has already decided to
withdraw the Endangerment Finding and that the agency violated procedural due process
56 See Memorandum to Docket EPA-HQ-OAR-2025-0194, "Projected Criteria, Air Toxics, and GHG Emissions
Impacts for the "Rescission of the Greenhouse Gas Endangerment Finding and Motor Vehicle Greenhouse
Gas Emission Standards Under the Clean Air Act" Final Rule."
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because the EPA had an unalterably closed mind on matters critical to the disposition of
the proceeding.
EPA Response
Comments pertaining to whether the EPA should be prepared to issue an interim final rule
(IFR) in response to a judicial stay of the final action or some other adverse court ruling are
premature and outside the scope of this action. Should the final action be subsequently
stayed, remanded, orvacated by a court, the EPA will take appropriate action consistent
with direction from that court. The EPA is not required to issue an IFR to set temporary GHG
standardsfor light- and medium-duty vehicles based on a recent modelyearorto
reinstate, for MY 2027 or later models, alternative GHG targets for small volume
manufacturers.
Commenters fail to support their claim that the EPA is obligated to consider specific
alternatives such as postponement of the proposed repeal until after the EPA's
reconsideration of the Endangerment Finding has concluded and any challenges to that
action are resolved. Neither the CAA nor the APA mandate an analysis of all alternatives to
the proposed action or require the EPA to consider postponingthe proposed repeal.
Commenters claim incorrectly that the EPA did not docket information relevant to the
proposal. Consistent with the requirements of CAA section 307(d)(3), the EPA placed all
data, information, and documents on which the proposal relied in the docket by the date of
publication of the proposed rule. The docket included correspondence with OMB as part of
the interagency review process under CAA section 307(d)(4)(B)(ii) (see docket item EPA-
HQ-OAR-2025-0194-0090) and information supporting the EPA's analysis in the RIA (see,
e.g., docket items EPA-HQ-OAR-2025-0194-0038 and EPA-HQ-OAR-2025-0194-0091). The
EPA is not required to docket internal, deliberative agency communications.
Comments pertaining to federal agencies' removal of information related to GHG
emissions, climate change, and human health from agency websites are not relevant to
this final action, as the EPA is not required to provide information on an agency website or
to ensure that any other federal agency is providing information on its website. Instead, the
CAA requires that the "[a]ll data, information, and documents ... on which the proposed
rule relies" be included in the EPA's rulemaking docket on the date the proposed rule is
published and likewise that all information or data on which the final action is based be
placed in the EPA's rulemaking docket as of the date the final action is published. See CAA
sections 307(d)(3) and 307(d)(6)(C). The EPA's proposed rule made clear that information
supportingthe proposal was available in the rulemaking docket. 90 FR 36288 (explaining
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how docket materials may be obtained). All information and data supportingthe final
action is also available in this same docket.
Commenters' claim that the EPA must provide an opportunity to comment on items that
are not a logical outgrowth of the proposal is speculative and unexplained. To the extent
the commenters intended to state that the EPA must allow the public an opportunity to
comment on any aspect of this final action that differs from the proposal, that claim is
unsupported. The CAA, like the APA, requires the EPA to provide one opportunity for public
comment on a "proposed" rule, not successive rounds of public comment on each change
to a proposed rule. CAA 307(d)(3), (4); see also Vermont Yankee Nuclear Power Corp. v.
NRDC, 435 U.S. 519 (1978) (courts cannot impose additional procedural requirements on
agencies beyond those required by statute); Connecticut Light & Power Co. v. NRC, 673
F.2d 525 (D.C. Cir. 1982) (the APA does not mandate iterative commenting). The preamble
to the proposal and related docket materials provided adequate notice of the EPA's
proposed action and supporting rationale, and the EPA has concluded that all aspects of
this final action are logical outgrowths of the Proposal. To the extent any aspect of the final
action is not a "logical outgrowth" of the Proposal, the CAA provides other means for relief.
CAA section 307(d)(7)(B) requires the EPA to commence a mandatory reconsideration
proceeding if a petitioner can demonstrate to the Administrator that it was "impracticable"
to raise his/her objection during the period for public comment on the proposed rule "or if
the grounds for such objection arose afterthe period for public comment (but within the
time specified for judicial review)" and "if such objection is of central relevance to the
outcome of the rule." CAA 307(d)(7)(B).
Comments pertaining to data regardingthe cumulative impacts analysis underlying the
EPA's draft RIA are not of central relevance to this final action. As explained in the proposal
(90 FR 36288, 36326) and in the preamble to the final action (footnote 2), the EPA is not
relying on the RIA prepared pursuant to Executive Order 12866 in any of the bases for this
final action. Except where expressly stated, none of the legal bases for repeal discussed in
section IV of the preamble reflect cost considerations, which are not relevant to
determining the best reading of CAA section 202(a)(1). Rather, cost is relevant to
demonstrating that whether and how to regulate GHG emissions is a major question of
policy within the ambit of the major questions doctrine and to the conclusion that the
existing GHG emission standards should be repealed forthe independent reason that it is
arbitrary and capricious to impose such costs when the standards have no demonstrable
impact. For those limited purposes, we discuss cost separately from, and do not rely upon,
the RIA prepared for Office of Management and Budget (OMB) review.
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Comments alleging the EPA prejudged the outcome of the proposal are inaccurate. While
the EPA believed the 2009 Endangerment Finding likely was not compliant with various
statutory requirements and initiated a rulemaking, the EPA remained opened at all times
duringthe rulemaking process on whether such non-compliance actually existed and, if so,
what corrective action the EPA could and should take.
6.11 Environmental Justice Topics
EPA Summary of Comments
Commenters mentioned that Executive Order 12898, Title VI of the Civil Rights Act, 42
U.S.C. § section 2000d and the Fourteenth Amendment's Equal Protection Clause together
indicate that the EPA is required to "identify and address, as appropriate,
disproportionately high and adverse human health or environmental effects" on minority
and low-income populations, that the EPA is prohibited from discrimination in federally
funded programs regardless of administrative priorities, and that EPA actions are required
to not intentionally discriminate against protected classes. Commenters claim that
rescinding the GHG standards will disproportionately harm communities of color and
therefore the proposal will violate the legal obligations and raise constitutional concerns.
EPA Response
With respect to EO 12898, on January 21, 2025, President Trump issued Executive Order
14173, "Ending Illegal Discrimination and Restoring Merit-Based Opportunity," which
revoked Executive Order 12898. Regarding Title VI, the EPA did not propose, nor is finalizing,
any federal financial assistance for any program or activity in this rulemaking, so
comments related to Title VI of the Civil Rights Act of 1964 are out of the scope of this
rulemaking. Finally, regarding Equal Protection, the EPA disagrees that this action raises
constitutional concerns. This rulemaking is not based on any constitutionally protected
status. As explained in detail in the preamble and throughout this RTC, the EPA is taking
this action based on the best reading of its authority under the CAA. The action is therefore
properly devoid any consideration of, and is clearly not "because of," its potential adverse
impacts on an identifiable group. Pers. Adm'rof Mass. v. Feeney, 442 U.S. 256, 279 (1979).
EPA Summary of Comments
Some commenters stated that finalizing this rule would result in liability in the future for the
United States including "climate reparations" for the harms that are being caused.
EPA Response
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The EPA believes in clean air for all Americans regardless of their race, sex, age, or income-
level. While out of scope of this rulemaking, there is no credible legal theory that this action
would or should result in any reparations for any potential harms in the future. In fact,
liability for any potential claimed harms from climate change must be weighed against the
significant benefits of those alleged actions. For example, individuals and some states
have claimed oil and natural gas companies "owe" due to their impact on climate change.
While we do not concede any impact due to any of their actions within this rule, the value
to national security, prosperity and every Americans daily conveniences must be
considered with respect to any reparations.
7 Other Comments
7.1 Federal Preemption
7.1.1 Federal Preemption under CAA section 209
EPA Summary of Comments
Commenters stated that preemption under CAA section 209(a) is not relevant to this rule or
the proper interpretation of CAA section 201 (a)(1). Therefore, they claimed that
commenting on it at this stage is premature, confusing, and would encourage the EPA to
speculate about topics that are not germane to the proceeding. Commenters also noted
that agencies "have no special authority to pronounce on preemption absent delegation
from Congress." Wyeth v. Levine, 555 U.S. 555, 577 (2009). They further noted that the EPA
is not entitled to deference insofar as it adopts an interpretation of the preemptive effect of
section 209(a).
EPA Response
The EPA did not propose, nor are we taking, any action with respect to preemption. Rather,
the EPA discusses preemption as a concern raised by regulated parties and responds to
comments insofar as commenters assert preemption concerns as a relevant consideration
that should be taken into account in the course of taking this final action. As such,
comments regarding the EPA's authority to alter preemption by regulation are outside the
scope of this final action.
EPA Summary of Comments
Some commenters supported the proposal's assertion that federal preemption under CAA
section 209 would still apply to GHG emission standards if the proposed rule is finalized.
Commenters asserted that the preemption provision in CAA section 209(a) is broader than
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the authority-to-regulate provision in section 202(a), as there is no limitation on the types
of "emissions" states are preempted from regulating. They claimed that if a vehicle or
regulation is subject to Title II, no state can issue emission standards for it.
Commenters argued that if preemption under section 209 required an Endangerment
Finding, it would undermine the purpose of section 209-thatthe EPA ratherthan the
states regulate emissions from new motor vehicles, and to avoid a patchwork of regulation.
This is true, they alleged, even if the EPA has determined not to impose emission
requirements for a particular pollutant. In support, commenters discussed California's
request for a waiver to regulate GHGs that preceded the 2009 Endangerment Finding,
which they argued supports the view that state GHG emission standards are preempted
under section 209 regardless of whether the EPA regulates GHG emissions under section
202.
Other commenters claimed that if the EPA finalizes its proposal, preemption under CAA
section 209 will no longer apply. These commenters rejected the EPA's position on
preemption in the proposal, asserting that the EPA's primary rationale for repealing the
Endangerment Finding and GHG standards is that section 202 does not apply to GHGs, but
only local and regional pollutants that endanger the public through exposure. Under this
reading, commenters claimed the EPA would have no section 202 authority to make an
Endangerment Finding for GHGs or regulate them at all - contradicting the Agency's
position on preemption.
Commenters asserted that the EPA misinterprets CAA section 209(a) in the proposal. They
claimed that when section 209(a) preempts states from adopting "any standard relating to
the control of emissions from new motor vehicles or new motor vehicle engines subject to
this part," the EPA interprets the language "subject to this part" to refer to "new motor
vehicles." Their argument follows that this is a weak reading of the statute because all new
motor vehicles and engines are subject to the part, rendering "subject to this part"
superfluous and unnecessary, offending the surplusage canon of statutory interpretation.
EPA Response
As stated previously, the EPA did not propose, nor are we taking, any action with respect to
preemption. Rather, the EPA discusses preemption as a concern raised by regulated
parties and responds to comments insofar as commenters assert preemption concerns as
a relevant consideration that should be taken into account in the course of takingthis final
action. As such, comments regarding the EPA's authority to alter preemption by regulation
are outside the scope of this final action.
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However, the EPA agrees with commenters that interpret preemption under CAA section
209(a) as broader than the scope of our authority to regulate in section 202(a)(1) or the way
that we choose to exercise it. Followingthe Supreme Court's decision in Loper Brightv.
Raimondo, we must inquire as to what is the "single, best meaning" of a statutory
provision. 603 U.S. 369, 399 (2024). Under CAA section 209(a)(1), States and localities are
preempted from adopting or attempting to enforce "any standard relating to the control of
emissions from new motor vehicles or new motor vehicle engine subject to this part." 42
U.S.C. § 7543(a) (emphasis added).
The EPA disagrees with commenters that argue that "subject to this part" refers to "any
standard," such that preemption would only apply insofar as the Agency has issued
standards for particular pollutants. Rather, the EPA believes that the best reading of this
provision is that "subject to this part" refers to "new motor vehicles or new motor vehicle
engines." Therefore, "any standard relating to the control of emissions" is not restricted to
pollutants for which the EPA has established standards under section 202(a)(1) but applies
to any attempt to regulate with emission standards for classes of new motor vehicles for
which the EPA has prescribed standards under part A of Title II of the CAA.
This reading is supported by the text, purpose, and history of the provision. It is also
consistent with how courts and the EPA have long treated the preemptive effect of CAA
section 209(a). The Supreme Court intimated that preemption under this provision is
exceedingly broad in Engine Mfrs. Ass'n v. S. Coast Air Quality Mgmt. Dist., stating that "the
language of section 209(a) is categorical" in failing to find an exception related to specific
kinds of standards. 541 U.S. 246, 257 (2004). Federal Circuit and District Courts have
unanimously expressed the understandingthat preemption under section 209(a) applies to
any emission standard adopted by a State. See, Chicago v. General Motors Corp., 467 F.2d
1262,1264 (7th Cir. 1972) ("The Act explicitly provided for preemption by the federal
government of the entire field of standards for emissions from new motor vehicles."); Motor
& Equip. Mfrs. Ass'n v. EPA, 627 F.2d 1095,1109 (D.C. Cir. 1979) ("Congress' entry into the
field and the heightened state activity after 1965 raised the spectre of an anarchic
patchwork of federal and state regulatory programs, a prospect which threatened to create
nightmares for the manufacturers. Acting on this concern, Congress in 1967 expressed its
intent to occupy the regulatory role over emissions control to the exclusion of all the
states."); Ass'n Int'lAuto. Mfrs. v. Comm'r, 208 F.3d 1, 3 (1 st Cir. 2000) ("When Congress
enacted the [CAA]... it expressly preempted all state regulation of new motor vehicle
emissions."); Am. Auto. Mfrs. v. Cahill, 152F.3d 196,198 (2d Cir. 1998) ("Under Section 209
of the Clean Air Act, exclusive control over'standards relating to the control of emissions
from new motor vehicles' is vested in the federal government, and the states are
preempted from regulating in the area."); Am. Auto. Mfrs. Ass'n v. Comm'r, 998 F.Supp. 10,
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13 (D. Mass. 1997) ("Section 209(a) expressly preempts all state regulation of motor vehicle
emissions ... Congress preempted the field of vehicle emission regulation for two reasons:
'to ensure uniformity throughout the nation, and to avoid the undue burden on motor
vehicle manufacturers which would result from different state standards.'") (quoting Motor
Vehicle Mfrs. Ass'nvN.Y. State Dep'tEnv'tl Conservation, 810 F.Supp. 1331, 1337 (N.D.N.Y.
1993)); Salt Lake City v. Volkswagen Grp. Am., Inc., 959 F.3d 1201, 1216 (9th Cir. 2020)
("209(a) precludes state or local governments from imposing any restriction that has the
purpose of enforcing emission characteristics for pre-sale, motor vehicles.").
The primary question of statutory interpretation question raised by commenters is whether
the clause "subject to this part" modifies the adjectival clause "from new motor vehicles or
new motor vehicle engines," or whether it is an independent adjectival clause that modifies
"any standard relating to the control of emissions."
When interpreting statutes, the touchstone is the statutory text, specifically the words and
phrases of a statute. See, e.g., Octane Fitness, LLC v. ICON Health & Fitness, Inc., 572 U.S.
545, 553 (2014). We assume that Congress intended words to have their "'ordinary,
contemporary, common meaning[s]."' Southwest Airlines v. Saxon, 596 U.S. 450, 455 (2022)
(quoting Sandiferv. United States Steel Corp., 571 U.S. 220, 227 (2014)). To determine this
meaning, words must be read in their context. Id. (quoting Parker Drilling Mgmt. Serv., Ltd.
v. Newton, 587 U.S. 601, 602 (2019)). Because words are given the meaning that proper
grammar and usage would assign them, the rules of grammar also govern statutory
interpretation unless their application would contradict legislative intent. See, e.g., Nielsen
v. Preap, 586 U.S. 392, 407-08 (2019).
The ordinary rules of grammar point towards "subject to this part" modifying"from new
motor vehicles or new motor vehicle engines." The adjectival phrase "relating to the control
of emissions" clearly modifies the verb "standards." Next, the adverbial phrase "from new
motor vehicles or new motor vehicle engines" modifies "relating to the control of
emissions." Adjectival clauses generally immediately follow the noun that they modify.
Therefore, because the adverbial phrase "from new motor vehicle engines" immediately
precedes "subject to this part," it would break with typical grammatical conventions for
"subject to this part" to modify "any standard."
This point is illustrated by a possible alternative construction of the sentence that follows
grammatical conventions and makes it clear that "subject to this part" modifies "any
standard." The provision may have read: "No State or political subdivision thereof shall
adopt or enforce any standard subject to this part relating to the control of emissions from
new motor vehicles or new motor vehicle engines," to make clear that "subject to this part"
modifies "standard" and follow grammatical conventions. Therefore, the rules of grammar
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support reading "subject to this part" to modify "new motor vehicles or new motor vehicle
engines." This analysis is also consistent with the "rule of the last antecedent," which
states that a limiting clause or phrase "should ordinarily be read as modifying only the noun
or phrase that it immediately follows." Barnhart v. Thomas, 540 U.S. 20, 26 (2003).
This grammatical point aside, the meaning of "subject to" in its statutory context in itself
reveals that "subject to this part" cannot refer to "any standard," but must refer to "new
motor vehicles or new motor vehicle engines." The EPA reads "subject to" in the context of
CAA section 209 to mean "governed or affected by." The Third Circuit looked at the phrase
"subject to" in several CAA provisions when interpreting the phrase in CERCLA, finding that
it meant "governed or affected by" throughout the CAA. Clean Air Council v. U.S. Steel
Corp., 4 F.4th 204, 209-10 (3d Cir. 2021); see also Texaco Inc. v. Duhe, 21A F.3d 911, 919
(5th Cir. 2001) (finding that "subject to" means "governed or affected by."). This is also the
definition of "subject to" found in the fourth edition of Black's Law Dictionary, published in
1968. Motor vehicles and motor vehicle engines are "governed or affected by" part A of title
II, as they are regulated under and must comply with regulations established under the
part. Standards, on the other hand, are not "governed or affected by" part A. Rather,
standards are what are doingthe governing and affecting motorvehicles and other
regulated parties. Therefore, it does not make sense to say that standards are "subject to"
part A. Black's Law Dictionary does offer two alternative definitions of "subject to" in
"obedient to" and "provided." However, standards are neither "obedient to" nor "provided"
part A of title II of the CAA; nor do either of these alternative definitions fit with "new motor
vehicles or new motor vehicle engines" in this context.
Finally, support for this meaning of "subject to this part" and that it modifies "new motor
vehicles or new motor vehicle engines" has support elsewhere within CAA Title II. CAA
section 203(a)(4) establishes prohibitions for "any manufacturer of a new motor vehicle or
new motor vehicle engine subject to standards prescribed under section [202] of this title
or part C of this subchapter." (emphasis added). Here there is no question that the "subject
to" clause is referring to new motor vehicles and new motor vehicle engines, as they are
governed or affected by standards under section 202 and part C. The presumption of
consistent usage should apply here to counsel that absent indication to the contrary, when
Congress uses a term to mean one thing in one part of the statute, it will mean the same
thing elsewhere in the statute - particularly where the term is used in related provisions
enacted at the same time. See, e.g., Powerex Corp. v. Reliant Energy Services, Inc., 551 U.S.
224, 232 (2007).
While some commenters point to canons of statutory construction in support of their
alternative interpretation of CAA section 209(a), as demonstrated above textual canons
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and the rules of statutory interpretation are in fact instructive in counseling in favor of the
EPA's own interpretation that preemption applies to any emission standard for "new motor
vehicles or new motor vehicle engines subject to this part," rather than for "any standard ..
. subject to this part." Insofar as commenters raise the rule against surplusage and allege
that "subject to this part" would be superfluous if it applied to "new motor vehicles or new
motor vehicle engines" because all new motor vehicles and engines are subject to part A of
Title II, an examination of the history of Title II reveals that this does not present a problem.
When the motor vehicle standard preemption provision was first adopted in the National
Emission Standards Act of 1967, section 202, which authorized the EPA to establish
emission standards for new motorvehicles and new motor vehicle engines, was much less
prescriptive than the present-day section 202. It broadly granted the Agency the authority
to "prescribe ... standards, applicable to the emission of any kind of substance from any
class or classes of new motorvehicles or new motor vehicle engines, which in his
judgment cause or contribute to, or are likely to cause or to contribute to, air pollution
which endangers the health or welfare of any persons." 81 Stat. 485 (1967). It does not
make reference to any class or classes of vehicles in particular. Therefore, it is conceivable
that the EPA could have declined to regulate certain classes of vehicles under CAA section
202. As such, those classes would not be "subject to this part" as contemplated in the
preemption provision. Because the language of the preemption provision in CAA section
209 is in large part unchanged from the original preemption provision, this reveals that
"subject to this part" is not merely surplusage but was included by Congress to refer to new
motorvehicles and engines.
Furthermore, the EPA agrees with commenters that note that California's 2005 preemption
waiver request under CAA section 209 to regulate GHGs from new motor vehicles supports
the Agency's position that preemption under CAA section 209(a) applies regardless of
whether the EPA has regulated a particular pollutant. California's GHG waiver request
preceded Massachusetts and the 2009 Endangerment Finding but followed the EPA's 2003
denial of a petition to regulate GHGs under CAA section 202(a) in part because the Agency
believed that it did not have the authority under the CAA to regulate GHGs. Even still,
California's waiver request demonstrates an understanding that preemption under section
209(a) is broader than the authority to regulate under CAA section 202(a). In litigation
following California and other states adopting GHG standards in anticipation of California's
waiver request being granted and allowing these standards to go into effect, courts and all
parties generally accepted as settled lawthat if the waiver was not granted, preemption
under CAA section 209(a) would apply to bar the standards. See, e.g., Green Mt. Chrysler
Plymouth Dodge Jeep v. Crombie, 508 F.Supp.2d 295, 302 (Vt. 2007) ("The Court and
parties have proceeded with this case on the assumption that EPA will grant California's
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waiver application. If it does not, of course, Vermont's regulation is preempted by the CAA's
section 209(a)."); Cent. Valley Chrysler-Jeep, Inc. v. Witherspoon, 456 F.Supp.2d 1160,1174
(E.D. Cal. 2006) ("Defendants do not contend that, under section 209(a), the challenged
regulations are not a 'standard relating to the control of emissions from new motor
vehicles.' Accordingly, the regulations are preempted unless the EPA issues a waiver under
section 209(b).") (citations omitted); Cent. Valley Chrysler-Jeep, Inc. v. Goldstene, 529
F.Supp.2d 1151,1155 (E.D. Cal 2007) ("The January 16 Order also declared that California's
program to regulate greenhouse gas emissions pursuant to California Health and Safety
Code ... is PREEMPTED by section 209(a) of the Federal Clean Air Act."). In 2008, the EPA
proceeded to deny California's waiver request to regulate GHGs, demonstrating that the
Agency has invoked preemption under CAA section 209(a) to apply when standards have
not been issued under section 202. See 73 FR 12156.
Additionally, "the purpose of Congress is the ultimate touchstone in every preemption
case." Wyeth v. Levine, 555 U.S. 555, 565 (2009). While the statutory purpose is
predominantly determined by the text, legislative history can be instructive and offer
additional insight. Legislative history reveals that Congress' purpose in including the
preemption provision at section 209(a) in the CAA was due to the auto industry's concerns
about the difficulty of complying with a range of diverse state standards and desire for a
single national standard. "The auto industry... was adamant that the nature of their
manufacturing mechanism required a single national standard in orderto eliminate undue
economic strain on the industry." S. Rep. No. 403, 90th Cong., 1 st Sess. 32 (1967). In
addition, the industry aimed to prevent "a chaotic situation from developing in interstate
commerce in new motor vehicles" and "obtain clear and consistent answers concerning
emission controls." H.R. Rep. No. 728, 90th Cong., 1st Sess. 20 (1967). See also Am. Auto.
Mfrs. Ass'n v. Comm'r, 998 F. Supp. 10 at 13 ("Congress preempted the field of vehicle
emission regulation for two reasons: 'to ensure uniformity throughout the nation and to
avoid the undue burden on motor vehicle manufacturers which would result from different
state standards.'") (quoting Motor Vehicle Mfrs. Ass'n v. N.Y. State Dep'tEnv'tl
Conservation, 810 F. Supp. 1331,1337 (N.D.N.Y. 1993)).
This purpose supports preemption of all State emission standards for new motor vehicles,
regardless of whether the particular emissions are regulated under section 202(a). The
provision would not serve to establish a uniform national standard for the regulation of
motor vehicle emissions nor protect against the proliferation of state standards if it allowed
States to impose individual standards on automakers for substances that the EPA does not
regulate under CAA section 202(a). To illustrate, imagine that State X adopted a regulation
limiting emissions of nitrogen (N2) (not NOx- pure nitrogen is what engines would emit if
they operated with perfect efficiency; the inefficiencies are what cause NOx formation).
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The EPA has never addressed pure N2 under CAA section 202(a)(1) and is not currently
aware of a reason it would have the authority to do so, as pure N2 is biologically inert and
makes up over 70 percent of the atmosphere. The State X regulation would be preempted
because it is a "standard relating to the control of emissions from new motor vehicles or
new motor vehicle engines subject to this part," and failure to preempt the State X
regulation would negate Congress' intent to have a single national standard for the
regulation of motor vehicle emissions.
The broad scope of preemption in section 209(a) is further supported by comparison with
other preemption provisions both in the CAA and other environmental laws that the EPA
administers. For example, CAA section 211 (c)(4) preempts State regulation of fuel and fuel
additives only if the EPA has addressed the fuel or fuel additive under its regulatory
authority by making a determination that no restrictions are necessary or by imposing
restrictions. 42 U.S.C. § 7545(c)(4)(A)-(C). Similarly, section 18 of the Toxic Substances
Control Act (TSCA) ties preemption to whether the EPA has taken particular actions tied to
particular chemical substances. 15 U.S.C. § 2617. Unlike these provisions, CAA section
209(a) does not clearly require the EPA to take any regulatory action - or decide not to take
such action - for preemption to apply.
The EPA also notes that this preemption discussion applies to certification, inspection, and
other approval requirements as well, which cannot be used as a roundabout means for
states to impose regulatory requirements where Congress has precluded them from setting
standards.
EPA Summary of Comments
Commenters cited Supreme Court precedent as recognizing that interstate air pollution is
an area of national concern and not a "matter[] of substantive law appropriately cognizable
by the states," as well as the general Constitutional principle that certain interstate matters
are inappropriate for state law to control. See Am. Elec. Power Co v. Connecticut, 564 U.S.
410, 426 (2011); Franchise TaxBd. ofCal. v. Hyatt, 587 U.S. 230, 246 (2019).
Other commenters expressed concern that abandoning the regulation of GHGs under CAA
section 202(a) will create an "unnavigable patchwork of state laws" and engender
considerable uncertainty and litigation for large GHG emission sources.
EPA Response
As noted in the response above, federal courts have long found that CAA section 209(a)
expressly preempts the entire field of adopting or enforcing standards for emissions from
new motor vehicles. See Chicago v. General Motors Corp., 467 F.2d 1262,1264 (7th Cir.
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1972) ("The Act explicitly provided for preemption by the federal government of the entire
field of standards for emissions from new motor vehicles."); Motor & Equip. Mfrs. Ass'nv.
EPA, 627 F.2d 1095, 1109 (D.C. Cir. 1979);Ass'n Int'lAuto. Mfrs. v. Comm'r, 208 F.3d 1,3
(1 st Cir. 2000); Am. Auto. Mfrs. v. Cahill, 152 F.3d 196, 198 (2d Cir. 1998; Am. Auto. Mfrs.
Ass'n v. Comm'r, 998 F.Supp. 10,13 (D. Mass. 1997). To the extent that commenters raise
issues related to whether or to what extent states are preempted from regulation of GHG
emissions from stationary sources, these comments are beyond the scope of this action.
However, the EPA notes that under International Paper Co. v. Ouellette, 479 U.S. 481, 496-
97 (1987), and its progeny, states may not use their law to regulate air emissions occurring
in another state. See e.g., Merrick v. Diageo Americas Supply, Inc., 805 F.3d 685, 692 (6th
Cir. 2015) (explaining that, although Ouellette is a Clean Water Act case, it is "persuasive"
with respect to the CAA, and applying Ouellette to analyze CAA preemption). States are
clearly authorized to regulate emissions within their own jurisdiction consistent with the
CAA. See CAA section 116. However, the Act does not empower states to apply their own
law to control emissions occurring outside their own jurisdiction. See Ouellette, 479 U.S. at
496-97; City of New York v. Chevron Corp., 993 F.3d 81, 91 (2d Cir. 2021). The federal
government has described its view of how constitutional principles such as the Foreign
Affairs Doctrine or the Commerce Clause also may support preemption of certain state
regulations of GHG emissions. See Plaintiffs' Motion for Summary Judgment, United States
etal. v. Vermont et al., Dkt. 50 (2:25-cv-00463-mkl, D. Vt.) (Sept. 15, 2025). While an
analysis of the application of such preemption principles to potential state programs
seeking to regulate GHG emissions from new motor vehicles or new motor vehicle engines
is beyond the scope of this rulemaking, we note that similar principles may apply to such
state programs.
7.1.2 Federal Preemption of Federal Common Law Claims
EPA Summary of Comments
Commenters claimed that if the EPA lacks the authority to set GHG standards under CAA
section 202, federal common law claims regarding GHGs are no longer preempted under
American Electric Power Co v. Connecticut (AEP). They alleged thaMEP held that federal
common law claims regarding GHG emissions are preempted because the CAA
empowered the EPA to set GHG limits, and that if the CAA does not, in fact, confer this
authority on the Agency, these claims are not preempted and can go forward.
EPA Response
The EPA disagrees with commenters' claims that federal common law claims are no longer
preempted because the Agency finds that it does not have the authority to set GHG
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standards under CAA section 202. The Supreme Court in AEP did not predicate the
displacement of federal common law claims on the EPA exercising regulatory authority.
Rather, in the context of CAA section 111, the Court specified that "[i]f EPA does not set
emissions limits for a particular pollutant or source of pollution, States and private parties
may petition on the matter, and EPA's response will be reviewable in federal court." AEP,
564 U.S. at 425. The Court explained that Congress exercised its judgment by prescribing
the standard for regulation and delegating to the EPA the decision "whether and how to
regulate." Id. at 426.
Preemption of federal common law claims is no less applicable where, as here, the EPA
does not regulate because Congress has not authorized such regulation as within the
scope of its legal standard for determining what air pollution is dangerous and subject to
regulation. In other words, Congress set out the standard - here, under section 202(a)(1) -
for when emissions are to be subject to regulation, and delegated to the EPA the decision
of whether and how to regulate emissions to meet that standard. As noted in the response
to comments above, the framework that Congress created under the CAA supplanted
federal common law in the area of interstate air pollution. The scheme Congress created
generally allows emissions unless and until the EPA determines that a statutory standard
for regulatory control is satisfied. Id. at 424. Where Congress has not authorized the EPA to
regulate certain emissions or types of emissions under one of these statutory standards,
litigants cannot supplant that judgment by usingfederal common law.
7.2 Compliance with the Environmental Research Development
Demonstration Authorization Act (ERDDAA)
EPA Summary of Comments
Commenters allege that the EPA violated the Environmental Research Development
Demonstration Authorization Act (ERDDAA) because it did not provide the proposed rule to
the Science Advisory Board (SAB). According to commenters, ERDDA requires the
Administrator to make available to the SAB "any proposed criteria document, standard,
limitation, or regulation" under the CAA at the same time it "is provided to any other Federal
agency for formal review and comment." 42 USC 4365(c)(1). The Agency must also provide
"relevant scientific and technical information ... on which the proposed action is based."
Commenters allege that the proposal is subject to this ERDDAA requirement because it is a
regulation that proposes to rescind all GHG vehicle standards. Commenters contrast this
to the Endangerment Finding, which as a "finding," was not required to be submitted to the
SAB. Commenters allege that the failure to provide the proposal to the SAB is "so serious
and related to matters of such central relevance to the rule that there is a substantial
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likelihood that the rule would have been significantly changed if such errors had not been
made," as required to invalidate the rule for procedural defects under section 307(d)(8) of
the CAA.
Commenters suggest that evidence supporting a finding that failure to submit the proposal
to the SAB satisfies the standard for invalidating a rule under section 307(d)(8) is largely
tied to the CWG report's alleged procedural deficiencies and the significant role that the
report and other scientific and technical analysis play in the proposal.
EPA Response
The EPA responds to these comments in section II.C.1 of the final action preamble.
7.3 Compliance with the Endangered Species Act (ESA)
EPA Summary of Comments
Commenters alleged the EPA has ignored its duty of consultation under section 7 of the
Endangered Species Act (ESA) in promulgating the Proposed Rule. Before finalizing the
Proposal or the accompanying Draft Regulatory Impact Analysis, commenters argued the
EPA must comply with the ESA consultation provisions. The commenters viewed the
proposed rule as a discretionary action that triggers the EPA's duty to consult. They
contended that scientific evidence shows that the Proposal "may affect," and is likely to
adversely affect, numerous listed species, and that it would cause jeopardy and adverse
modification to critical habitat for some sensitive species such as the polar bear.
Commenters explained that section 7 of the ESA requires a federal agency (here, the EPA)
to consult with the United States Fish and Wildlife Service or the National Oceanic and
Atmospheric Administration (depending on the location of the species) if the agency
determines that any action on its part "may affect" any listed species or critical habitat.
Comments quoted the following passage from a court decision: "'May affect' purposefully
sets a low bar: 'Any possible effect, whether beneficial, benign, adverse or of an
undetermined character, triggers the formal consultation requirement.'" Growth Energy v.
EPA, 5 F.4th 1, 30 (D.C. Cir. 2021). Commenters alleged the Proposal crosses the "may
affect" threshold because the resulting large increases in GHGs and criteria air pollutant
emissions would affect hundreds of federally listed species as well as critical habit, which
they assert are threatened by GHG-driven climate change, as well as NOx and S02
emissions.
Accordingto commenters, the increase in GHG emissions resulting from the Proposal will
not only adversely affect sea ice-dependent polar bears, ringed seals, and bearded seals,
but it will also adversely modify their critical habitat and cause jeopardy for polar bears by
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diminishing the species' likelihood of survival and recovery. Commenters contended the
Proposal's increases in GHG emissions will also adversely affect many other climate-
sensitive listed species and their critical habitat such as corals and coastal and island
species. Commenters also asserted that the Proposal's resulting increases in NOx criteria
air pollutants will likewise adversely affect listed species such as the endangered bay
checkerspot butterfly which was listed specifically due to the harms from nitrogen
deposition from vehicle exhaust.
Some comments claimed that the EPA's action is discretionary based on various
arguments, including court decisions stating that the EPA has no nondiscretionary duty to
"bring its regulations into conformity with statutory law." Similar arguments state that the
nondiscretionary duties under the CAA are limited to those with a "date-certain deadline."
EPA Response
The EPA does not agree that it is required consult under section 7 of the ESA.
This consultation requirement applies only to actions where there is discretionary federal
involvement or control. 50 CFR 402.03; see also, Nat'lAss'n of Home Builders v. Defs. of
Wildlife, 551 U.S. 644, 669 (2007) ("NAHB"). This final action is not such an action. This
final action is required by the best reading of the CAA and controlling legal precedent and is
not being taken as a matter of agency discretion.
As explained in Section V.A of the preamble to final action, the best reading of CAA section
202(a) is that this provision does not authorize the EPA to assert jurisdiction over GHG
emissions based on global climate change concerns in a standalone Endangerment
Finding. Similarly, as explained in section V.B of the final action preamble, the agency lacks
the clear congressional authorization needed underthe major questions doctrine to decide
the United States' response to global climate change. The EPA has therefore concluded
that it has no discretion to regulate GHG emissions under CAA section 202(a) because
such emissions by any class or classes of new motor vehicles do not "cause, or contribute
to, air pollution which may reasonably be anticipated to endanger public health or welfare."
Absent findings of endangerment and causation or contribution, the EPA lacks statutory
authority to prescribe GHG standards for passenger cars, light-duty trucks, motorcycles,
buses, medium-duty vehicles, and heavy-duty vehicles and engines under CAA section
202(a)(1). Here, as in the NAHB case, nothing in the text of CAA section 202(a) grants the
EPA authority to modify vehicles standards based on species-related impacts.
Commenters incorrectly equate the existence of agency discretion to reconsider a prior
rulemaking with discretionary action over the substance of that rulemaking. As explained in
sections IV.A and V of the final action preamble, the EPA concludes that the 2009
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Endangerment Finding and the GHG emissions standards for motor vehicles that followed
exceeded the EPA's authority. The Agency's discretion to now revisit and correct those
errors does not equate to discretionary action to regulate the subject of the prior rules. In
fact, such discretion to regulate GHG emissions from vehicles is precisely what is lacking
in this case.
Furthermore, even if this were a discretionary agency action, this action has no effect on
listed species or critical habitat for ESA purposes, and therefore the EPA would have no
duty to consult under section 7 of the ESA. Notwithstanding that this action is
nondiscretionary, the EPA has considered the potential impact of this action to affect listed
species or designated critical habitat of these species and has concluded that any such
impacts cannot be attributed to the EPA's action because they are too uncertain and
attenuated to be reasonably viewed as "but for" caused by our action or "reasonably
certain to occur." See 50 C.F.R. § 402.02.57
A 2008 Department of the Interior Solicitor's Opinion, which remains in effect today,
closely examined this issue in the context of GHGs and concluded: "...where the effects at
issue result from climate change potentially induced by GHGs, a proposed action that will
involve the emission of GHG cannot pass the 'may affect' test, and is not subject to
consultation under the ESA and its implementing regulations." DOI Solicitor's Opinion No.
M-37017, "Guidance on the Applicability of the Endangered Species Act Consultation
Requirements to Proposed Actions Involving the Emissions of Greenhouse Gases" (Oct. 3,
2008) at 2, https://www.doi.gov/sites/doi.opengov.ibmcloud.com/files/uploads/M-
37017.pdf. That Opinion further states, "[gjiven the nature of the complex and independent
processes active in the atmosphere and the ocean acting on GHGs, the causal link simply
cannot currently be made between emissions from a proposed action and specific effects
on a listed species or its critical habitat. Specifically, science cannot say that a tiny
incremental global temperature rise that might be produced by an action under
consideration would manifest itself in the location of a listed species or its habitat.
57 The EPA is also aware of certain revisions recently proposed by the U.S. Fish and Wildlife Service and the
National Marine Fisheries Service to the section 7(a)(2) implementing regulations. 90 FR 52600 (Nov. 21,
2025). The EPA notes that these revisions include proposed regulatory language further explaining the
"reasonably certain to occur" standard. Id. at 52607 (proposed section 402.17). Among other things, that
proposed language states that any conclusion that an activity or a consequence is reasonably certain to
occur must be based on clear and substantial information and identifies relevant considerations, such as
whether a consequence is remote in time from the action, is geographically remote, or is reached through a
lengthy causal chain involving many steps. Id. Although the Services have not yet taken final action on those
revisions, the EPA notes that substantially similar regulatory language has previously been included in the
Services'final regulations and, although not necessary for EPA's conclusions here, would further support the
EPA's conclusion that consultation is not required. See 84 FR 44976,45018 (Aug. 27, 2019) (previously
withdrawn in relevant part by 89 FR 24268, 24298 (Apr. 5, 2024)).
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Similarly, any observed climate change effect on a member of a particular listed species or
its critical habitat cannot be attributed to the emissions from any particular source." Id. at
6.
As applied to GHG emissions from motor vehicles, the complex and lengthy chain of
causality between: 1) GHG emissions from certain classes of motor vehicles regulated by
the EPA and 2) any effects on listed species or critical habitat that may occur as a result of
global temperature and sea level measurement does not satisfy either the "but for" or the
"reasonably certain to occur" tests. The EPA is not able to make a causal link for purposes
of Section 7(a)(2) that would "connect the dots" between this action, any consequent
emissions from covered motor vehicles, climate change, and any particularized impacts to
listed species or critical habitats. The EPA reached a comparable conclusion in 2020 with
regard to setting C02 emissions standards. 85 FR 25252-4. The reasoning from that action
is also applicable to the repeal of C02 standards.
As to air pollution from emissions of criteria pollutants like NOx, this action is not a but for
cause of any effect on criteria pollutant emissions. First, the EPA is not changing the
vehicle emission standards for these pollutants, so this action does not directly allow
greater criteria pollutant emission from vehicles. Second, to the extent the repeal of GHGs
emissions standards could have an indirect effect on criteria pollutant emissions or
concentrations in the ambient air, the EPA has reached the same conclusion as to criteria
air pollutant emissions from vehicles. While the environmental effect of these emissions
may differ from GHG emissions, the impacts of criteria pollutant emissions are dependent
on where they occur to a degree much more significant than GHG emissions. See 85 FR at
25254-55. Even if there is an indirect increase in criteria pollutant emissions after this final
action, the EPA cannot determine with reasonable certainty where those additional
emissions will occur, as those impacts may not be uniform across the country. The agency
thus lacks data sufficient to draw conclusions on impacts on particular listed species or
designated critical habitat. The indirect impacts on air quality at any particular location
(such as where a listed species or designated critical habitat is located) are more
ambiguous than for global atmospheric concentrations of C02 over the long term. This
supports the same conclusion for criteria pollutant emissions as for C02 emissions and
climate change. For these reasons, the rescission of the Endangerment Finding and
associated rescission of all GHG emission standards for light-duty (LD), medium-duty
(MD), and heavy-duty (HD) vehicles and engines manufactured or imported into the United
States for model years (MY) 2012 to 2027 and beyond are not the "but for" cause of any
effects to federally listed species or their habitat that are reasonably certain to occur.
Because the EPA concludes on this basis that there would be "no effects," section 7(a)(2)
consultation is not required.
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EPA Summary of Comments
Commenters pointed out that section 7(d) of the ESA requires that, after initiation of
consultation under section 7(a)(2), a federal agency "shall not make any irreversible or
irretrievable commitment of resources with respect to the agency action which has the
effect of foreclosing the formulation or implementation of any reasonable and prudent
alternative measures which would not violate subsection (a)(2) of this section." According
to commenters, section 7(d) of the ESA is a preventative measure designed to ensure that
the status quo is preserved duringthe consultations process and clarifies the requirements
of section 7(a). Commenters said that any action taken priorto completion of consultation
must not interfere with the ability of the agency to implement reasonable and prudent
measures determined to be necessary to avoid jeopardy to a protected species or adverse
effects to its critical habitat.
Commenter argued that enactment of the Proposal would bean irreversible or irretrievable
commitment of resources within the meaning of this ESA provision because cars and
trucks built without the protections of current law, expected to be on the road for decades,
will emit more GHGs and criteria pollutants into the atmosphere than they would under the
status quo, and those pollutants will remain in the atmosphere causing harm for as long as
thousands of years. Here, commenters said, the status quo is the protection from harm
that the Endangerment Finding and the EPA truck and auto GHG rules provide.
Commenters asserted that eliminating those protections will lead to irreversible adverse
changes to air pollution that will harm endangered species.
EPA Response
The EPA does not agree with the commenter. Because consultation is not required for the
reasons set forth above, the EPA does not have an obligation under ESA section 7(d) to
refrain from "mak[ing] any irreversible or irretrievable commitment of resources with
respect to the agency action which has the effect of foreclosing the formulation or
implementation of any reasonable and prudent alternative measures which would not
violate subsection (a)(2) of this section."
7.4 Interaction with Other CAA Provisions
EPA Summary of Comments
Commenters referenced a past EPA statement that Title I of the CAA, sets out "what
amounts to a 'blueprint' by which nonattainment areas will attain the NAAQS." 62 FR 1150,
1154 (January8,1997). Commenters quoted the EPA as having said the blueprint "couples
SIP reductions with reductions from mobile source measures promulgated by EPA under
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Title II of the Act." Id. The commenter cites CAA section 176, which is part of Title I (located
within Part D for plan requirements for nonattainment areas). Commenters argued
Congress likely did not contemplate that the EPA would seek to relax or eliminate on-the-
books measures that are actively needed by nonattainment areas and did not exclude the
EPA from general conformity requirements. Commenters asserted the EPA is required to
follow the blueprint and cannot disregard how its proposed action will increase ozone
precursors. According to commenters, the proposal is not compliant with CAA section 176
and arbitrary and unreasoned for entirely lacking any discussion of criteria pollutant issues,
which is an undeniably "important aspect of the problem" for Title II rulemaking. See Motor
Vehicle Mfrs. Assn. v. State Farm, 463 U.S. 29, 43 (1983).
EPA Response
The EPA is not changing the vehicle emission standards for ozone precursors and other
criteria pollutants, so the final action does not result in a direct increase in ozone precursor
emissions from vehicles. The EPA is likewise not changing any requirement for state
implementation plans (SIPs) required to attain and maintain compliance with the NAAQS.
If any state is unable to achieve attainment the ozone NAAQS with the benefit of these
unaltered vehicle standards for criteria pollutants, that state will need to address the
ambient air quality conditions through its SIP in the same manner as it would if the GHG
standards remained applicable. To the extent this rule could have an indirect effect on
ozone precursor emissions, state planning requirements would continue to apply to
address attainment of the NAAQS in the same manner, regardless of whether the source of
additional ozone precursor emissions results indirectly from the repeal of GHG standards
for vehicles or other causes (such as population growth or industrial expansion).
Nothing in this rule alters the requirement of CAA section 176, which requires as a
condition of federal funding that activities conform to the requirement of a state
implementation plan. Since this rule does not allow an increase in direct emissions of
ozone precursor emissions, there is no reason to think pending or planned activities
supported by federal funding would no longer be in conformity with state plans because of
this rule.
Further, to the extent this rule may have an indirect effect on ozone precursor emissions or
ozone concentrations from global climate change concerns, the chain of causation for any
effect on public health or welfare is as attenuated, if not more so, than that for GHG
emissions. To the extent that climate change is projected to increase exposure to
concentrations of criteria pollutants in the ambient air because of effects such as higher
temperatures or displacement of existing human settlement patterns, this extends the
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causal chain for GHG emissions. Any such harm would not result from "air pollution" in the
form of local or regional exposure to GHGs.
EPA Summary of Comments
According to commenters, if the EPA rescinds the Finding, it could have ripple effects - for
instance, on how the Prevention of Significant Deterioration program addresses carbon
dioxide, on California's waivers as discussed, and even on considerations under NEPA for
federally funded highway projects (which currently account for GHG emissions as a
pollutant of concern). Commenters argued the EPA's proposal insufficiently addresses
these collateral consequences. They said the EPA's proposal briefly notes it is not "at this
time" reopening other rules like fuel economy labeling or measurement methods, but it
does propose sweeping removal of GHG-related provisions across multiple parts of the
CFR. Commenters contended that, without a coherent plan, the abrupt excision of GHG
considerations from regulatory frameworks could cause confusion and gaps. As an
example, commenters pointed out that the proposal asks which regulatory provisions to
retain or remove, which commenters contend is essentially admitting uncertainty about
how to unwind the integrated climate-related requirements. Commenters expressed
concern that this ad hoc approach risks unraveling efficient regulatory schemes that have
combined criteria pollutant and GHG controls in complementary ways. They alleged the
potential for litigation and regulatory chaos is high.
EPA Response
The EPA acknowledges that this action will have an effect on other state and federal
actions. Within the preamble of the final action and the response to comment document,
the Agency discusses those impacts where appropriate.
This final action is required by controlling law and is not being taken as a matter of agency
discretion. Thus, the EPA may not decline to take this action based on the effects it could
have on other federal programs to regulate emissions of GHG gases, whether from
programs to control emissions from stationary sources or address the environment
impacts of highway construction. This is likewise the case for programs administered by
states to address emissions from stationary sources or vehicles.
As explained in section V.A of the preamble to final action, the best reading of CAA section
202(a) is that this provision does not authorize the EPA to assert jurisdiction over GHG
emissions based on global climate change concerns in a standalone Endangerment
Finding. Similarly, as explained in section V.B of the final action preamble, the agency lacks
the clear congressional authorization needed underthe major questions doctrine to decide
the United States' response to global climate change. The EPA has therefore concluded
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that it has no discretion to regulate GHG emissions under CAA section 202(a) because
such emissions by any class or classes of new motor vehicles do not "cause, or contribute
to, air pollution which may reasonably be anticipated to endanger public health or welfare."
The EPA thus has no discretion to retain rules that regulate GHGs emissions under CAA
section 202(a) because of downstream effects the repeal of these rules may have on any
federal or state programs to regulate GHG emissions.
EPA Summary of Comments
Commenters argued that the text and purposes of the CAA require a conservative,
precautionary approach to protection of public health and welfare. In the commenters
view, neither the regulatory mandates in sections 202(a) and 231 (a), 42 U.S.C. §§ 2571 (a),
7571 (a), nor the authorization elsewhere in Title II, id. §§ 7547(a)(4) (nonroad vehicles and
engines), can reasonably be read to require complete scientific certainty in order to make
an endangerment determination. According to commenters, Because the premise for the
rescission of the Endangerment Finding is that the allegedly "new" science in the DOE
report raises uncertainty about the scientific basis for the Endangerment Finding, that
premise is grounded in a fundamental misreading of the statute. Commenters contended
the CAA does not, in fact, require the level of certainty claimed by the EPA and, in fact,
compels the EPA to act to protect public health and welfare even where the science is
unsettled.
EPA Response
As discussed in the preamble, the EPA is not basingthis final action on uncertainty about
the scientific basis for the Endangerment Finding. As discussed in the prior response, this
final action is based on the best reading of section 202(a) of the CAA and controlling legal
precedent. Since the level of certainty in the science regarding climate change is not a
basis for this final action, it is not necessary for the EPA to take a position here on the level
of certainty required under the CAA provisions cited by the commenter.
7.5 General Arbitrary and Capricious Arguments
EPA Summary of Comments
A commenter stated that under Section 706 of the APA, the "EPA must exercise its
rulemaking powers in a way that is not "arbitrary, capricious, an abuse of discretion, or
otherwise not in accordance with law." In this regard, the EPA is required, in the context of
its rulemaking, to duly consider all "important aspect[s] of the problem" and to examine all
"relevant data." A commenter stated that the EPA did not consider the relevant issues as
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required by the APA and did not provide a rationale for its choices based on cursory
treatment of available information, including global warming.
EPA Response
As a threshold matter, the standard for review of this final action is supplied by CAA section
307(d)(9), not the APA. The EPA does not dispute its general responsibilities under the CAA
and APA to duly consider all important aspects of the problem, examine all relevant data,
and provide a reasoned basis for its conclusions. See, e.g., Motor Vehicle Manufacturers
Ass'n v. State Farm Mutual Automobile Insurance Co., 463 U.S. 29 (1983) (agency changing
course by rescinding a rule must "examine the relevant data and articulate a satisfactory
explanation for its action"). But the record demonstrates that the EPA has adequately
considered all important aspects of the issues before it, including the data relevant to the
basis for this final action, and commenters fail to support their claim that the EPA has
failed to do so. With respect to the comments provided regarding the impacts of global
warming, as explained in section V of the preamble for this final action, the EPA is
rescinding the Endangerment Finding on the basis of its interpretation of CAA section
202(a), under which the EPA concludes that Congress did not authorize the Agency to
regulate GHG emissions from new motor vehicles and new motor vehicle engines to
address global climate change. That legal interpretation is sufficient to support rescission
of the Endangerment Finding and repeal of the related GHG standards. As the EPA does not
adopt or rely on the proposed global warming scientific alternative rationale in this final
action, the Agency does not need to, and is not legally required to, summarize or respond
to comments that address that unfinalized alternative - please see section 3.1 of this
Response to Comments document.
EPA Summary of Comments
Commenters alleged the Proposal represents an arbitrary and capricious rejection of
evidence because no new scientific evidence justifies overturning the 2009 determination.
They said the EPA criticizes the Endangerment Finding because it purportedly failed to
consider "leakage" (a concept that evaluates whether the regulated community can
escape regulation by finding locations with more relaxed standards). In this case,
accordingto commenters, the EPA asserts that by not considering whether businesses
would move to other nations with laxer standards, the Endangerment Finding is
fundamentally flawed. 90 FR at 36305. Commenters argued that such a consideration is
absent from the statute and further that it makes no sense. According to commenters, the
standards apply to vehicles sold in the United States, whether they are domestically
produced or imported. In light of this reality, commenters argued, leakage could not
possibly occur, even if that were an appropriate consideration.
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While an agency's judgment on scientific facts within its area of expertise is normally
afforded deference, commenters asserted that in this case we have a judgment that has
been: (1) reaffirmed by the agency at least twelve times over the course of 13 years, most
recently just three years ago, (2) has been affirmed by the United States Court of Appeals
for the D.C. Circuit after close review, and (3) is consistent with the conclusions of the
leading international court addressing the obligations of states under treaty law and
international law binding on the United States and nearly every other nation in the world,
rendered just eight days before the publication of the Proposal. Contrary to that view,
commenters argued that the agency offers a newly coined opinion based on dubious
science, based on a draft report prepared by five individuals that differs from not only the
agency's prior consistent determinations and the conclusions of the International Court of
Justice (ICJ), but the judgment of hundreds of other scientists, all National Academy of
Sciences reports that have addressed the issue, the reports of all other national academies
of sciences that have addressed the matter, every recent United States national climate
assessment and the conclusions of the Intergovernmental Panel on Climate Change
(including related to extreme weather event attribution), as found by the ICJ. Under such
circumstances, commenters contended, deference should be afforded to the agency's
past judgment, not its newly minted and unsupported views, and the agency should bear
the burden of demonstrating why it has reversed direction because its prior judgments
were incorrect. The scientists participating in these comments asserted the EPA has not
met that burden and could not meet that burden, given the current state of the science.
According to commenters, the EPA's proposed repeal of the Endangerment Finding and the
mobile source standards is just one of a number of actions whose cumulative impacts
should have been considered together. Commenters pointed out that the current Proposal
was preceded by a proposal to reinterpret section 111 of the CAA to preclude regulation of
GHG emissions from power plants on a rationale that would eliminate all regulation of
GHGs under section 111. That proposal was preceded by the Congressional repeal of
incentives in the so-called One Big Beautiful Bill. Together, commenters argued, these
actions would eliminate virtually all federal regulation of GHGs and most federal incentives
to reduce them, resulting in uncontrolled and largely unabated emissions from the world's
second largest contributor of GHGs. Commenters contended that the EPA should have
considered the cumulative impacts of those actions. Commenters claimed the EPA has
not analyzed the cumulative impacts of all of the EPA's decisions taken together, including
this Proposal or the cumulative effect of all of these decisions, whether made by the EPA or
not.
EPA Response
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The final action is based on the EPA's conclusion that it lacks statutory authority to regulate
GHG emissions from motor vehicles and engines under CAA section 202(a). The EPA is not
making any new findings under CAA section 202(a) and is not finalizing the alternative
proposal to base rescission and repeal of the Endangerment Finding on new findings by the
Administrator under CAA section 202(a). Thus, comments pertainingto the science of
climate change are not pertinent to the bases forthis final action and out of scope, which
are legal in nature. See section VI of the preamble to the final action forfurther discussion
of the additional proposed bases that the EPA is not finalizing. Because this final action
rests on the EPA's reassessment of the Endangerment Finding based on the best reading of
CAA section 202(a), we disagree with the commenter's claim that deference should be
afforded to the EPA's prior conclusions.
The commenter identifies no statutory support for a claim that the EPA is obligated to
analyze the cumulative impacts of multiple EPA actions pertainingto the regulation of GHG
emissions and pertainingto federal incentives to reduce GHG emissions. Section 202(a)
requires the Administrator to "prescribe" and "from time to time revise ... standards" for
certain air pollutants emitted by new motor vehicles and new motor vehicle engines "in
accordance with the provisions of this section."58 Unless provided otherwise by statute, an
agency may revise or rescind prior actions so long as it acknowledges the change in
position, provides a reasonable explanation for the new position, and considers legitimate
reliance interests in the prior position.59 Nothing in the statute conditions the EPA's general
factions taken under different statutory authorities, or consideration of the cumulative
effect of the rescission together with such other actions.
7.6 Children's Constitutional Claims
EPA Summary of Comments
Commenters asserted that the EPA's rulemaking deprives children and youth of
fundamental rights to life, personal security, other liberties, and children's equal protection
of the law. U.S. Const, amend. V, XIV, § 1. According to commenters, the proposed rule is
violative of federal law, the best available science on protecting the health and lives of
children, and the legal mandate that agency decision-making does not deprive children of
their fundamental constitutional rights. In addition, commenters argued the Proposed Rule
relies on faulty scientific bases includingthe findings in the DOE report Impacts of Carbon
58 42 U.S.C.§ 7521(a)(1).
59 See FDA v. Wages & White Lion Invs., LLC, 604 U.S. 542, 568-70 (2025J; FCC v. Fox Television Stations, Inc.,
556 U.S. 502 (2009); Motor Vehicle Mfrs. Ass'n v. State Farm Mut. Auto. Ins. Co., 463 U.S. 29 (1983); Clean Air
Council v. Pruitt, 862 F.3d 1, 8 (D.C. Cir. 2017) ("Agencies obviously have broad discretion to reconsider a
regulation at any time").
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Dioxide Emissions on the U.S. Climate, misapplies the EPA's preemptive authority,
encourages more expensive forms of energy sources, misapplies the Supreme Court's
interpretation of "any air pollutant" in Massachusetts v. EPA, 549 U.S. 497 (2007), and
violates the major questions doctrine and separation of powers.
EPA Response
Commenters raise numerous issues addressed elsewhere in this RTC including:
challenging the proposed action on a scientific basis, noting costs of specific energy
sources, challenging the findings in the DOE report Impacts of Carbon Dioxide Emissions
on the U.S. Climate, citing the Supreme Court's interpretation of "any air pollutant" in
Massachusetts v. EPA, 549 U.S. 497 (2007), and raising the major questions doctrine. As
discussed in the preamble, the EPA is not basing this final action on uncertainty about the
scientific basis forthe Endangerment Finding. As discussed in this RTC, this final
action is based on the best reading of section 202(a) of the CAA and controlling legal
precedent. The section of the RTC title "Legal Framework for Action" provided more
detailed response to the legality of the Action and Commenters assertions.
Commenters' statements regarding this action's constitutionality are conclusory,
Commenters assume that the action would violate the constitution with no support, then
state why an action that is unconstitutional is not permissible. Commenters provide no
analysis or support as to why the actions would be unconstitutional, stating that
Commenters "have proven in the September 16-17, 2025, evidentiary hearing in Lighthiser,
that you are engaged in an unconstitutional rulemaking, to implement the President's
unconstitutional Executive Orders 14154,14156, and 14261, in violation of U.S. Const,
amend. V, XIV, § 1, by 'unburdening' fossil fuels so they may be 'unleashed' and
'revitalized'." Commenters are welcome to their opinion of what they "have proven";
however, the case at issue, Lighthiser v. Trump, No.: CV-25-54-BU-DLC (D. Mont.) was
dismissed with prejudice, and the court did not address Plaintiffs' constitutional claims
stating "[pjursuant to Juliana, the relief sought in this case is beyond the bounds of this
Court's Article III authority, a fact that cannot be cured by amendment. Therefore, this
matter will be dismissed with prejudice." Curiously, Commenters also direct the Agency to
Juliana, which the Lighthiser court read "to mandate" the dismissal. Juliana v. United
States, No.: 15-cv-01517 (D. Or.) was dismissed following a 9th Circuit Order mandating that
the District Court dismiss Plaintiffs' constitutional claims, a decision Plaintiffs appealed to
the Supreme Court which denied cert. The other federal case Commenters reference
heavily- Genesis B. v. EPA, No.: 2:23-CV-10345-MWF (C.D. Cal.) - was likewise dismissed
by the District Court in reliance on Juliana. The remaining case - Held v. Montana, No. CDV-
2020-307 (Mont. 1 st Jud. Dist. Ct.) - is a state case interpreting the Montana State
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Constitution and has no precedential value with regard to federal actions. The same is true
of commenters' assertions regarding high courts of other nations (see also section 7.8 of
this Response to Comments document regarding International Considerations).
Finally, Commenters listed numerous references to other documents and requested that
the Agency "include all referenced evidence above and below in the administrative record."
The Administrative Record includes documents which the Agency used for support of the
final action, the proposed rule clearly stated that a "written comment is considered an
official comment and should include discussion of all points you wish to make. The EPA will
generally not consider comments or comment contents located outside of the primary
submission {i.e., on the web, cloud, or other file sharing system)." 90 FR 36288, 36288 (Aug.
1,2025).
7.7 International Law Considerations
EPA Summary of Comments
Commenters asserted that the Proposed Rule is inconsistent with the United States'
international law obligations as interpreted by international and regional courts.
Commenters argued that the United States has binding international legal obligations to
reduce GHG emissions, found in multiple sources of treaty-based and customary
international law, including longstanding principles that predate the UN climate
agreements. Commenters cited three international and regional courts as recently offering
what commenters characterize as authoritative opinions clarifying the scope and content
of these binding climate obligations. Commenters assert that, taken together, these
sources offer a coherent body of obligations for preventing and remedying climate harm,
including through climate mitigation measures rooted in the best available science found
in the IPCC reports.
Commenters specifically argued that, because the requirements of the UNFCCC and the
Paris Agreement are contained in a Senate-ratified treaty and a congressional-executive
agreement, they are the law of the land under Article VI, cl. 2 of the Constitution and
binding on the United States in international law. Commenters reasoned that, under
longstanding precedent applied by both Republican and Democratic administrations,
executive agencies must interpret statutes, where fairly possible, in a manner consistent
with international law. Commenters asserted that the Supreme Court made this clear over
two centuries ago in Murray v. Schooner Charming Betsy.
Commenters quoted Article III, paragraph 3 of the UNFCCC as providing that "[t]he Parties
should take precautionary measures to anticipate, prevent or minimize the causes of
climate change and mitigate its adverse effects," and that "lack of full scientific certainty
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shall not be used as a reason for postponing such measures." They read a recent
International Court of Justice (ICJ) ruling to confirm that the climate treaties "incorporate
the precautionary approach or principle." Moreover, the commenters said, the ICJ found
that the treaties are "legally binding" on the parties. Commenters concluded the
requirement to apply the precautionary principle must therefore equally be binding on the
EPA, as the responsible agency within a member state bound by these international law
rules. Moreover, commenters argued, because the precautionary principle is a part of
customary international law, they asserted it also binds the EPA and informs statutory
interpretation, including the CAA's precautionary design. Murray v. Schooner Charming
Betsy, 2 Cranch 64,118 (1804); Societe Nationale Industrielle Aerospatiale v. United States
District Court, 482 U.S. 522, 555, 567 (1987) (Blackmun concurrence).
According to commenters, the EPA's rule is inconsistent with the United States' obligation
to implement its Nationally Determined Contributions (NDCs) underthe Paris Agreement
through domestic measures, including emissions-control standards forthe transportation
sector. Commenters said that the United States specifically pointed to the "new vehicle
emission limits for passenger cars, light trucks, pickups and vans for Model Years 2027-
2032" as an element of its implementation plan in its most recent NDC. The commenters
argued the United States must implement that NDC and ensure that each NDC is
progressively ambitious. In commenters view, deregulating vehicle emissions runs counter
to these obligations and thus undermines international law.
Commenters alleged that international law obligations require the United States to do the
following: use all means at its disposal to prevent environmental harm caused by GHG
emissions; mitigate emissions in a manner consistent with limiting warmingto 1.5°C and
reflective of progressively more ambition, including by regulating emissions by private
actors; and acquire and analyze the best available scientific knowledge toward those ends.
This includes, according to commenters, regulating vehicle emissions, one of the largest
sources of U.S. GHG emissions. Commenters allege that decliningto regulate GHG
emissions from vehicles cannot be reconciled with such legal obligations. Commenters
argue that deregulation cannot mitigate climate change and its effects; it can only heighten
the risk of further harm. In commenters view, deregulating those emissions runs afoul of
the principle of non-retrogression, fundamental to international obligations related to
climate change.
Commenters argued that the Proposed Rule's reasoning is also inconsistent with the duty
of cooperation, which commenters asserted requires all States to contribute to global
mitigation efforts. Commenters said one of the most important ways that States effectively
cooperate to prevent harm from climate change is by complying with their obligation to do
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their fair share. According to commenters, failing to do so - as co mm enters alleged the EPA
proposed in respect of one of the United States' highest-emitting sectors - undermines that
obligation and only exacerbates the collective action problem. Commenters argued U.S.
vehicle emissions are so substantial that regulating them makes a difference no matter
what happens elsewhere.
EPA Response
Commenters assert that rescission of the Endangerment Finding under the CAA is in
contradiction to international legal obligations. The EPA disagrees. First, the EPA notes that
the U.S. is in the process of withdrawing from participation in climate change treaties,
including the UNFCCC. Second, the EPA is not a party or subject to the jurisdiction of the
other international agreements, bodies and courts referenced by the commenters. In
particular, commenters point to the international climate change treaties, the UNFCCC,
the Kyoto Protocol and the Paris Agreement. Among other commitments, commenters
specifically point to the Paris Agreement's Nationally Determined Contributions (NDCs),
which created only the commitmentto produce NDCs according to nationally determined
priorities, in addition to striving to strengthen such plans over time. Furthermore, of these
three treaties, only the UNFCC was ratified by the U.S. with Congressional consent. The
Kyoto Protocol was signed, but not ratified, and the U.S. joined the Paris Agreement by
Executive Action without Congressional consent. As such, these two treaties do not have
the force of law on the U.S. and do not supersede existing U.S. law.
Finally, even if the United States was not withdrawing from these various treaties, we do not
concede that any aspect of this final action contravenes any international law by which the
United States is bound.
EPA Summary of Comments
Commenters cited three international and regional courts -the International Court of
Justice (ICJ), InternationalTribunalforthe Law of the Sea (ITLOS), and Inter-American Court
of Human Rights (lACtHR) - as having recently offered authoritative opinions clarifying the
scope and content of binding climate obligations.
In commenters view, the Proposal fails to address the conclusions of the International
Court of Justice (ICJ) in its unanimous decision in Obligations of States in Respect of
Climate Change, 2025 I.C.J. (July 23), https://www.icj-cij.org/sites/default/files/case-
related/187/187-20250707- pre-01-00-en.pdf. ("Obligations of States"). The ICJ rendered
its decision before the Proposal's publication in a case in which the United States
appeared and participated. Commenters read the ICJ opinion to find the following: (1) The
consequences of climate change are severe and far-reaching; they affect both natural
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ecosystems and human populations; (2) Rising temperatures are causing the melting of ice
sheets and glaciers, leading to sea level rise and threatening coastal communities with
unprecedented flooding. Accordingto commenters, the ICJ found that nations are
obligated to protect the climate system and other parts of the environment from
anthropogenic GHG emissions, based on multiple legal sources including the UN Charter,
climate treaties (UNFCCC, Kyoto Protocol, Paris Agreement), customary international law,
environmental treaties, and international human rights law. Commenters argued these
obligations include mitigation, adaptation, and cooperation duties, guided by principles
such as sustainable development, precaution, and intergenerational equity. The
commenters contended that the Court affirmed that the duty to prevent significant harm
and the duty to cooperate apply to all nations, with due diligence as the governing
standard. Commenters said the ICJ also concluded that when nations breach these
obligations, they incur legal consequences underthe customary international law of nation
responsibility, including duties to cease the harmful conduct, guarantee non-repetition,
and provide reparation. In commenters reading, the opinion emphasized that obligations
related to climate protection apply equally to harm caused to other nations, vulnerable
populations, and future generations.
Commenters also cited high courts of other nations, the European Court of Human Rights,
and the United Nations General Assembly as having affirmed the human right to a clean,
healthy, and sustainable environment, and the fundamental importance of a life-sustaining
climate system as essential to other human rights. Accordingto commenters, courts
across the U.S., the world, and at the International Court of Justice have specifically ruled
that governments allowing fossil fuel pollution causes constitutional injuries and human
rights violations. International Court of Justice, Advisory Opinion on the Obligations of
States in Respect of Climate Change, General List No. 187, July 23, 2025. Commenters
argue that every nation has a legal and moral obligation to cease its conduct that
perpetuates fossil fuel use and climate change and to take measures (like in these
rulemaking processes) to work to substitute renewable energy for fossil fuels.
EPA Response
Commenters highlight the 2025 International Court of Justice (ICJ) advisory opinion on
Obligations of States in respect of Climate Change as somehow obligating the U.S. to
protect the climate system from anthropogenic GHG emissions. However, not only are
international advisory opinions of the ICJ not legally binding,60 but even for the binding
60 Interpretation of Peace Treaties with Bulgaria, Hungary and Romania (Advisory Opinion) (First Phase) [1950]
ICJ Rep 65, 71: "The consent of States, parties to a dispute, is the basis of the Court's jurisdiction in
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decisions of the ICJ, the U.S., since 1986, has not accepted the ICJ's compulsory
jurisdiction.61
Commenters also refer to advisory opinions of the International Tribunal for the Law of the
Sea (ITLOS) and the Inter-American Court of Human Rights (lACtHR). The non-legally
binding character of advisory opinions aside, the U.S. has not ratified the American
Convention on Human Rights and therefore is not subject to the jurisdiction of the lACtHR.
Similarly, the U.S. is not subject to the jurisdiction of ITLOS which settles disputes arising
under the UN Convention on the Law of the Sea (UNCLOS), because the U.S. is not a party
to the Convention.
Commenters note that the high courts of other nations, the European Court of Human
Rights, and the United Nations General Assembly, have affirmed a human right to a clean,
healthy, and sustainable environment. The U.S. has no international legal obligation to
abide by affirmations of the high courts of other nations or the European Court of Human
Rights.62 Furthermore, the U.S. has not affirmed a human right to a clean, healthy, and
sustainable environment per se, including in its engagement with the UN General Assembly
and other UN bodies.63
EPA Summary of Comments
Commenters argued that Congress instructed the EPA to account for global effects when
regulating pollution under the CAA. Section 202(a)(1) directs the EPA to regulate emissions
of air pollutants from new motor vehicles or engines that "may reasonably be anticipated to
endanger public health or welfare." Commenters said section 302(h) defines "welfare" to
include effects on "climate" and "weather," which commenters allege are inherently global
phenomena. According to commenters, CAA section 115 further authorizes the EPA to act
where U.S. emissions "cause or contribute to air pollution which may reasonably be
contentious cases. The situation is different in regard to advisory proceedings even where the Request for an
Opinion relates to a Legal question actually pending between States. The Court's reply is only of an advisory
character: as such, it has no binding force."
61 See Letter from U.S. Secretary of State Shultz to the U.N. Secretary General, Oct.7,1985, declaration of
acceptance of ICJ compulsory jurisdiction terminated, effective six months from the date of the letter, and
United States of America Termination Notification received on 7 October 1985 (With effect from 7 April 1986.)
Registered ex officio on 7 October 1985 published in United Nations Treaty Series, vol 1408 at 270.
62 See Roper v. Simmons | 543 U.S.551 (2005) majority opinion in which it was affirmed that "the opinion of the
world community is not controlling.
63 See U.S. Explanation of Position on HRC-52 Right to Environment Resolution, April 6, 2023: "As the United
States indicated in our Explanation of Vote on UNGA resolution 76/300, we supported the political and moral
aspirations reflected in that resolution. That said, the development of a right to a clean, healthy, and
sustainable environment needs to be carried out in a manner that is consistent with international law."
https://geneva.usmission.gov/2023/04/06/hrc-52-right-to-environment-resolution/.
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anticipated to endanger public health or welfare in a foreign country." Commenters argue
that this is an unmistakable implementation of the customary obligation to prevent
transboundary environmental harm. The commenters asserted that the D.C. Circuit has
read these provisions to endorse the EPA's reasoned consideration of cross-border and
international effects where relevant to a regulatory program. In the commenters view, the
Proposed Rule effectively reads those provisions out of the statute by disregarding the
global effects of climate change and treating cumulative harm as a reason not to regulate.
Commenters criticized the EPA for construing the CAA as disallowing any such regulation,
in part because of the global and cumulative nature of the harm GHG emissions cause.
EPA Response
As explained in the preamble to final action, the best reading of CAA section 202(a) is that
this provision does not authorize the EPA to assert jurisdiction over GHG emissions based
on global climate change concerns in a standalone Endangerment Finding. Similarly, the
preamble explains the agency lacks the clear congressional authorization needed under
the major questions doctrine to decide the United States' response to global climate
change. The EPA has therefore concluded that it has no discretion to regulate GHG
emissions under CAA section 202(a) because such emissions by any class or classes of
new motor vehicles do not "cause, or contribute to, air pollution which may reasonably be
anticipated to endanger public health or welfare." Absent findings of endangerment and
causation or contribution, the EPA lacks statutory authority to prescribe GHG standards for
passenger cars, light-duty trucks, motorcycles, buses, medium-duty vehicles, and heavy-
duty vehicles and engines under CAA section 202(a)(1).
CAA section 115 authorizes the EPA to require controls for domestic emissions that
contribute to air pollution that endangers public health or welfare in another country only
when, among other things, that country has adopted reciprocal protections for emissions
into the United States. This provision does not address GHG emissions and supports the
conclusion that Congress does not presume that general authorities in the CAA
encompass international emissions. Rather, Congress knows how to provide for the
consideration of and regulation in response to international emissions, and has not done
so for GHG emissions, whether in CAA section 202(a) or otherwise. Furthermore, the
requirements of section 115 apply only when the Administrator or Secretary of State has
reason to believe emissions from the US "may reasonably be anticipated to endanger
public health or welfare in a foreign country." As reflected in this rule, the EPA Administrator
has not found that emissions from any class or category of new motor vehicles may
reasonably be anticipated to endanger public health or welfare. The Secretary of State has
not informed the Administrator of any contrary finding.
316
-------
Additionally, the existence of section 115, which includes an international component,
runs counter to the commenter's argument that section 202(a) must also include an
international component. Specifically, as mentioned elsewhere in the preamble to the final
action and the response to comment document, when members of Congress wished to
speak to international impacts, they did so directly such as in CAA section 115.
7.8 Severability Clause
EPA Summary of Comments
Several commenters recommended adding a severability clause to the final action to allow
for cancelingthe GHG standards as originally adopted for modelyear (MY) 2027 and later
vehicles and engines even if the Endangerment Finding is not rescinded (or if it is restored
in the future).
Commenters also recommend that the EPA include a severability clause clarifying that
even if the repeal of the Endangerment Finding or the revision of other GHG emissions
standards is invalided by a court, it does not impact the reconsideration of the GHG
emissions standards in this rulemaking. In addition, commenters requested a severability
clause for each section of the rulemaking so that if a court invalidates one section, the
balance of the final action would remain in effect.
Commenters argued that a severability clause was needed because the EPA's proposal
identifies multiple alternative rationales for the proposed action. They said the Agency's
rationale would be improved by expressly delineating each of its rationales and explaining
that they are severable in any final action. Commenters asserted that clear delineation
promotes transparency and ensures the Agency's reasoning remains intact even if one
strand is rejected in litigation. These commenters read Supreme Court and lower courts to
have emphasized that agency action is more defensible when supported by multiple
independent bases, each capable of sustainingthe rule. They argued that explicit
recognition of severability would thus promote administrative clarity and predictability.
Commenters argued a severability clause would be a logical outgrowth of the proposed
rule because interested parties/commenters could reasonably have anticipated the
substance of the final action from the proposed rule and thus had a meaningful
opportunity to comment. These commenters pointed out that the EPA included a variety of
arguments and justifications for its proposed reconsideration and other actions. Because
some of the justifications apply to only some portions of the proposed rule, commenters
contended that it should not come as a surprise to any commenter that the EPA would
want to insulate provisions with a severability clause.
317
-------
Several commenters that requested a severability clause focused specifically on the
Greenhouse Gas Emissions Standards for Heavy-Duty Vehicles: Phase 3 (HD GHG Phase 3)
program,64 noting that the Phase 3 standards are infeasible and that the rule was an "EV
mandate" in violation of the major questions doctrine. These commenters noted their
urgent need for regulatory certainty regarding the HD GHG Phase 3 standards that are
currently set to apply for MY 2027. One approach suggested by commenters to provide
near-term certainty was that the EPA rescind the Phase 3 program separate from the
Endangerment Finding rescission and allow industry to continue to meet the MY 2024
standards that are currently in place under the HD GHG Phase 2 program.65 Another
commenter suggested the EPA use broad discretion to finalize, as a severable alternative,
standards that are achievable by existing fleets without EVs, such as freezing the GHG
emission standards at MY 2026 levels.
EPA Response
The EPA agrees with commenters' suggestion to include language on severability of the
final action's legal arguments and has added additional language to the preamble.
Regarding comments on phase 3 of the HD rule, as stated in the preamble, the EPA is
removing all GHG emission standards as noted because we lack authority to retain these
standards. Therefore, we are not putting in place alternative GHG emission standards and
are not committing to alternative GHG emission standards in a separate action. As stated
previously, companies are still able to continue producing HD vehicles that meet the now
non-existent HD engine and vehicle requirements if they so choose.
Appendix A: Mass Comment Campaigns
There were 170 mass comment campaigns submitted prior to the close of the comment
period by various organizations. The mass comment campaigns are listed in the table
64 89 FR 29440 (Apr. 22, 2024).
65 81 FR 73478 (Oct. 25, 2016).
318
-------
below, organized by the sponsoring organization (if known), along with the number of
signatures.
Many of the mass comment campaigns provided general support or opposition to the EPA's
proposed rule and did not provide specific comments. Other mass comment campaigns
did provide more specific comments on various aspects of the EPA's proposal or provided
specific support for another commenter's submission. The EPA has responded to those
specific comments within the preamble for the final action and/or this Response to
Comments document.
We note that many of the mass comment campaign comments provided comments
unrelated to the basis for this final action (the basis described in section V of the preamble
for the final action). These include comments on the EPA's proposed Draft RIA, comments
on the proposed bases the EPA requested comment on but is not relying upon for the final
action, or other topics outside the scope of this final action. Where comments contained in
mass comment campaigns are relevant to this final action, the EPA has responded to those
comments in the final action preamble and/orthis Response to Comments document.
Document ID
Commenter
Date
# Signatures
EPA-HQ-OAR-2025-0194-0145
Mass Comment Campaign sponsored by
American LungAssociation (ALA)
8/8/25
228
EPA-HQ-OAR-2025-0194-0251
Mass Comment Campaign sponsored by
Sierra Club
8/14/25
16,098
EPA-HQ-OAR-2025-0194-0465
Mass Comment Campaign sponsored by
National Religious Partnership for the
Environment
9/2/25
1010
EPA-HQ-OAR-2025-0194-0466
Mass Comment Campaign sponsored by
Franciscan Action Network
9/2/25
2415
EPA-HQ-OAR-2025-0194-0777
Mass Comment Campaign sponsored by
National Parks Conservation Association
9/9/25
221
EPA-HQ-OAR-2025-0194-0778
Mass Comment Campaign sponsored by
Union of Concerned Scientists
9/16/25
1000
EPA-HQ-OAR-2025-0194-0779
Mass Comment Campaign sponsored by
Creation Justice Ministries
9/16/25
62
EPA-HQ-OAR-2025-0194-0780
Mass Comment Campaign sponsored by
Town of Concord Climate Action Committee
9/18/25
5
EPA-HQ-OAR-2025-0194-0781
Mass Comment Campaign sponsored by
California Interfaith Power & Light (CIPL)
9/18/25
4667
EPA-HQ-OAR-2025-0194-0782
Mass Comment Campaign sponsored by
Green America
9/18/25
9465
EPA-HQ-OAR-2025-0194-1423
Mass Comment Campaign sponsored by
Earthjustice
9/22/25
4635
EPA-HQ-OAR-2025-0194-1424
Mass Comment Campaign sponsoring
organization unknown
9/22/25
8765
EPA-HQ-OAR-2025-0194-1425
Mass Comment Campaign sponsored by
Center for Biological Diversity
9/22/25
13,985
EPA-HQ-OAR-2025-0194-1426
Mass Comment Campaign sponsored by
National Audubon Society
9/22/25
21,013
319
-------
Document ID
Commenter
Date
# Signatures
EPA-HQ-OAR-2025-0194-1427
Mass Comment Campaign sponsored by
Natural Resources Defense Council (NRDC)
9/22/25
13,253
EPA-HQ-OAR-2025-0194-1428
Mass Comment Campaign sponsored by
Natural Resources Defense Council (NRDC)
9/22/25
43,169
EPA-HQ-OAR-2025-0194-1429
Mass Comment Campaign sponsoring
organization unknown
9/22/25
25
EPA-HQ-OAR-2025-0194-1430
Mass Comment Campaign sponsored by
Earthjustice
9/22/25
6326
EPA-HQ-OAR-2025-0194-1431
Mass Comment Campaign sponsored by
Climate Hawks Vote Civic Action
9/22/25
13788
EPA-HQ-OAR-2025-0194-1432
Mass Comment Campaign sponsoring
organization unknown
9/19/25
9040
EPA-HQ-OAR-2025-0194-1433
Mass Comment Campaign sponsored by
350.org
9/19/25
9125
EPA-HQ-OAR-2025-0194-1434
Mass Comment Campaign sponsored by
Earth Day Network (d.b.a. EARTHDAY.ORG)
9/19/25
7269
EPA-HQ-OAR-2025-0194-1435
Mass Comment Campaign sponsored by
First Congregational Church of Berkeley
9/21/25
31
EPA-HQ-OAR-2025-0194-1436
Mass Comment Campaign sponsored by
Lexington Climate Action Network (LexCAN)
9/21/25
43
EPA-HQ-OAR-2025-0194-1437
Mass Comment Campaign sponsored by
Boston Catholic Climate Movement
9/21/25
24
EPA-HQ-OAR-2025-0194-1438
Mass Comment Campaign sponsored by
Green America
9/22/25
9465
EPA-HQ-OAR-2025-0194-1439
Mass Comment Campaign sponsored by
Friends of the Earth
9/22/25
13,079
EPA-HQ-OAR-2025-0194-1440
Mass Comment Campaign sponsored by The
Climate Reality Project
9/22/25
7584
EPA-HQ-OAR-2025-0194-1441
Mass Comment Campaign sponsored by
Alliance of Nurses for Healthy Environments
9/22/25
67
EPA-HQ-OAR-2025-0194-1442
Mass Comment Campaign sponsored by
American Geophysical Union (AGU)
9/22/25
919
EPA-HQ-OAR-2025-0194-1443
Mass Comment Campaign sponsored by
Evergreen Action
9/22/25
20,236
EPA-HQ-OAR-2025-0194-1444
Mass Comment Campaign sponsored by
Expert Working Group on Climate Change
and Health
9/22/25
114
EPA-HQ-OAR-2025-0194-1445
Mass Comment Campaign sponsored by
California Interfaith Power & Light
9/22/25
154
EPA-HQ-OAR-2025-0194-1446
Mass Comment Campaign sponsoring
organization unknown
9/22/25
108
EPA-HQ-OAR-2025-0194-1447
Mass Comment Campaign sponsored by
Students of the Baltimore Polytechnic
Institute (BPI)
9/22/25
25
EPA-HQ-OAR-2025-0194-1448
Mass Comment Campaign sponsoring
organization unknown
9/22/25
34
EPA-HQ-OAR-2025-0194-1449
Mass Comment Campaign sponsoring
organization unknown State Public Utility
Commissions
9/22/25
28
EPA-HQ-OAR-2025-0194-1450
Mass Comment Campaign sponsoring
organization unknown
9/21/25
25
EPA-HQ-OAR-2025-0194-1451
Mass Comment Campaign sponsored by
Better Path Coalition
9/22/25
4072
EPA-HQ-OAR-2025-0194-1452
Mass Comment Campaign sponsored by
Sustainable Marblehead
9/19/25
17
320
-------
Document ID
Commenter
Date
# Signatures
EPA-HQ-OAR-2025-0194-1453
Mass Comment Campaign sponsored by
Moms Clean Air Force (testimony)
9/21/25
19
EPA-HQ-OAR-2025-0194-1454
Mass Comment Campaign sponsored by
Citizens Climate Lobby (CCL)
9/21/25
9
EPA-HQ-OAR-2025-0194-1455
Mass Comment Campaign sponsored by
National Parks Conservation Association
(NPCA)
9/22/25
20
EPA-HQ-OAR-2025-0194-1456
Mass Comment Campaign sponsored by
Earthworks
9/19/25
3120
EPA-HQ-OAR-2025-0194-1458
Mass Comment Campaign sponsored by
Grace United Methodist Church
9/11/25
86
EPA-HQ-OAR-2025-0194-1459
Mass Comment Campaign sponsored by
Chesapeake Climate Action Network
(CCAN)
9/22/25
7932
EPA-HQ-OAR-2025-0194-1460
Mass Comment Campaign sponsored by
Ocean Conservancy
9/22/25
3861
EPA-HQ-OAR-2025-0194-1461
Mass Comment Campaign sponsoring
organization unknown (Nathan Sweet et al)
9/22/25
10
EPA-HQ-OAR-2025-0194-1462
Mass Comment Campaign sponsoring
organization unknown (Antonio M Bento et
a I)
9/22/25
9
EPA-HQ-OAR-2025-0194-1504
Mass Comment Campaign sponsored by
American Geophysical Union (AGU)
9/22/25
919
EPA-HQ-OAR-2025-0194-1505
Mass Comment Campaign sponsored by
Pace Energy and Climate Center; Pace
Environmental Law Review and Pace
Environmental Law Society
9/22/25
64
EPA-HQ-OAR-2025-0194-1506
Mass Comment Campaign sponsoring
organization unknown
9/19/25
61
EPA-HQ-OAR-2025-0194-1507
Mass Comment Campaign sponsored by
Electric Vehicle Association
9/22/25
739
EPA-HQ-OAR-2025-0194-1728
Mass Comment Campaign sponsored by The
Climate Reality Project
9/17/25
4934
EPA-HQ-OAR-2025-0194-2611
Mass Comment Campaign sponsored by
Climate Action Campaign
9/17/25
563
EPA-HQ-OAR-2025-0194-2612
Mass Comment Campaign sponsored by
Earth-Org, Clean Water Action, Clean Water
Fund, SEIU
9/17/25
1063
EPA-HQ-OAR-2025-0194-2613
Mass Comment Campaign sponsored by
Chesapeake Climate Action Network, The
Medical Society Consortium on Climate &
Health, PSR Pennsylvania
9/17/25
500
EPA-HQ-OAR-2025-0194-2614
Mass Comment Campaign sponsored by
Evergreen Action, Greenlatinos Luchado por
la Liberacion Ambiental, Young Gifted Green
9/17/25
420
EPA-HQ-OAR-2025-0194-2615
Mass Comment Campaign sponsored by
NRDC, Sierra Club and Union of Concerned
Scientists
9/17/25
393
EPA-HQ-OAR-2025-0194-2616
Mass Comment Campaign sponsored by
Elders Climate Action, MOMS Clean Air
Force, Plug in America, PSR Physicians for
Social Responsibility
9/17/25
528
EPA-HQ-OAR-2025-0194-2617
Mass Comment Campaign sponsored by
California Interfaith Power & Light, Great
Lakes Business Network, Michigan
Clinicians for Climate Action (MiCCA)
9/17/25
500
321
-------
Document ID
Commenter
Date
# Signatures
EPA-HQ-OAR-2025-0194-2618
Mass Comment Campaign sponsored by
Center for Biological Diversity, Clean Air
Council and Earthjustice
9/17/25
529
EPA-HQ-OAR-2025-0194-2619
Mass Comment Campaign sponsored by
Public Citizen, SBN
9/17/25
535
EPA-HQ-OAR-2025-0194-2620
Mass Comment Campaign sponsored by
Electric Vehicle Association, Southern
Alliance for Clean Energy
9/17/25
269
EPA-HQ-OAR-2025-0194-2621
Mass Comment Campaign sponsored by
Alliance of Nurses for Healthy Environments,
Change the Chamber, Michigan Interfaith
Power & Light
9/17/25
388
EPA-HQ-OAR-2025-0194-2622
Mass Comment Campaign sponsored by
Environmental Defense Fund, LCV, National
Wildfire Federation
9/17/25
500
EPA-HQ-OAR-2025-0194-2623
Mass Comment Campaign sponsoring
organization unknown
9/17/25
320
EPA-HQ-OAR-2025-0194-2624
Mass Comment Campaign sponsoring
organization unknown
9/17/25
500
EPA-HQ-OAR-2025-0194-2625
Mass Comment Campaign sponsored by
EarthDay.org
9/17/25
7096
EPA-HQ-OAR-2025-0194-2626
Mass Comment Campaign sponsoring
organization unknown
8/3/25
2196
EPA-HQ-OAR-2025-0194-2627
Mass Comment Campaign sponsoring
organization unknown
8/4/25
539
EPA-HQ-OAR-2025-0194-2628
Mass Comment Campaign sponsoring
organization unknown.
8/4/25
22
EPA-HQ-OAR-2025-0194-2629
Mass Comment Campaign sponsoring
organization unknown
8/5/25
22,263
EPA-HQ-OAR-2025-0194-2630
Mass Comment Campaign sponsoring
organization unknown
8/6/25
275
EPA-HQ-OAR-2025-0194-2631
Mass Comment Campaign sponsoring
organization unknown.
8/6/25
32
EPA-HQ-OAR-2025-0194-2632
Mass Comment Campaign sponsoring
organization unknown
8/6/25
246
EPA-HQ-OAR-2025-0194-2633
Mass Comment Campaign sponsoring
organization unknown
8/7/25
3727
EPA-HQ-OAR-2025-0194-2634
Mass Comment Campaign sponsoring
organization unknown.
8/7/25
20
EPA-HQ-OAR-2025-0194-2635
Mass Comment Campaign sponsoring
organization unknown
8/8/25
10,541
EPA-HQ-OAR-2025-0194-2636
Mass Comment Campaign sponsoring
organization unknown.
8/8/25
12
EPA-HQ-OAR-2025-0194-2637
Mass Comment Campaign sponsoring
organization unknown.
8/8/25
66
EPA-HQ-OAR-2025-0194-2638
Mass Comment Campaign sponsoring
organization unknown
8/8/25
975
EPA-HQ-OAR-2025-0194-2639
Mass Comment Campaign sponsoring
organization unknown.
8/8/25
16
EPA-HQ-OAR-2025-0194-2640
Mass Comment Campaign sponsoring
organization unknown.
8/11/25
27
EPA-HQ-OAR-2025-0194-2641
Mass Comment Campaign sponsoring
organization unknown
8/11/25
260
EPA-HQ-OAR-2025-0194-2642
Mass Comment Campaign sponsoring
organization unknown.
8/11/25
13
322
-------
Document ID
Commenter
Date
# Signatures
EPA-HQ-OAR-2025-0194-2643
Mass Comment Campaign sponsoring
organization unknown.
8/12/25
22
EPA-HQ-OAR-2025-0194-2644
Mass Comment Campaign sponsoring
organization unknown.
8/12/25
45
EPA-HQ-OAR-2025-0194-2645
Mass Comment Campaign sponsoring
organization unknown.
8/12/25
17
EPA-HQ-OAR-2025-0194-2646
Mass Comment Campaign sponsoring
organization unknown.
8/15/25
73
EPA-HQ-OAR-2025-0194-2647
Mass Comment Campaign sponsoring
organization unknown.
8/16/25
13
EPA-HQ-OAR-2025-0194-2648
Mass Comment Campaign sponsoring
organization unknown
8/19/25
11,348
EPA-HQ-OAR-2025-0194-2649
Mass Comment Campaign sponsoring
organization unknown
8/20/25
1645
EPA-HQ-OAR-2025-0194-2650
Mass Comment Campaign sponsoring
organization unknown.
8/21/25
59
EPA-HQ-OAR-2025-0194-2651
Mass Comment Campaign sponsoring
organization unknown.
8/22/25
13
EPA-HQ-OAR-2025-0194-2652
Mass Comment Campaign sponsoring
organization unknown
8/23/25
82
EPA-HQ-OAR-2025-0194-2653
Mass Comment Campaign sponsoring
organization unknown
8/24/25
1997
EPA-HQ-OAR-2025-0194-2654
Mass Comment Campaign sponsoring
organization unknown.
8/27/25
18
EPA-HQ-OAR-2025-0194-2655
Mass Comment Campaign sponsoring
organization unknown.
9/1/25
14
EPA-HQ-OAR-2025-0194-2656
Mass Comment Campaign sponsoring
organization unknown.
9/3/25
81
EPA-HQ-OAR-2025-0194-2657
Mass Comment Campaign sponsoring
organization unknown.
9/3/25
58
EPA-HQ-OAR-2025-0194-2658
Mass Comment Campaign sponsoring
organization unknown.
9/3/25
16
EPA-HQ-OAR-2025-0194-2659
Mass Comment Campaign sponsoring
organization unknown.
9/5/25
13
EPA-HQ-OAR-2025-0194-2660
Mass Comment Campaign sponsoring
organization unknown.
9/5/25
21
EPA-HQ-OAR-2025-0194-2661
Mass Comment Campaign sponsoring
organization unknown.
9/7/25
18
EPA-HQ-OAR-2025-0194-2662
Mass Comment Campaign sponsoring
organization unknown
9/8/25
232
EPA-HQ-OAR-2025-0194-2663
Mass Comment Campaign sponsoring
organization unknown.
9/8/25
14
EPA-HQ-OAR-2025-0194-2664
Mass Comment Campaign sponsoring
organization unknown.
9/8/25
62
EPA-HQ-OAR-2025-0194-2665
Mass Comment Campaign sponsoring
organization unknown
9/8/25
102
EPA-HQ-OAR-2025-0194-2666
Mass Comment Campaign sponsoring
organization unknown.
9/8/25
62
EPA-HQ-OAR-2025-0194-2667
Mass Comment Campaign sponsoring
organization unknown
9/10/25
190
EPA-HQ-OAR-2025-0194-2668
Mass Comment Campaign sponsoring
organization unknown.
9/11/25
12
EPA-HQ-OAR-2025-0194-2669
Mass Comment Campaign sponsoring
organization unknown
9/11/25
164
EPA-HQ-OAR-2025-0194-2670
Mass Comment Campaign sponsoring
organization unknown.
9/15/25
19
323
-------
Document ID
Commenter
Date
# Signatures
EPA-HQ-OAR-2025-0194-2671
Mass Comment Campaign sponsoring
organization unknown
9/15/25
658
EPA-HQ-OAR-2025-0194-2672
Mass Comment Campaign sponsoring
organization unknown.
9/17/25
18
EPA-HQ-OAR-2025-0194-2673
Mass Comment Campaign sponsoring
organization unknown.
9/19/25
10
EPA-HQ-OAR-2025-0194-2674
Mass Comment Campaign sponsoring
organization unknown.
9/19/25
11
EPA-HQ-OAR-2025-0194-2675
Mass Comment Campaign sponsoring
organization unknown.
9/21/25
10
EPA-HQ-OAR-2025-0194-2676
Mass Comment Campaign sponsoring
organization unknown.
9/21/25
12
EPA-HQ-OAR-2025-0194-2677
Mass Comment Campaign sponsoring
organization unknown.
9/22/25
10
EPA-HQ-OAR-2025-0194-2678
Mass Comment Campaign sponsoring
organization unknown.
9/22/25
14
EPA-HQ-OAR-2025-0194-2679
Mass Comment Campaign sponsoring
organization unknown.
9/22/25
14
EPA-HQ-OAR-2025-0194-2680
Mass Comment Campaign sponsoring
organization unknown
8/22/25
48,118
EPA-HQ-OAR-2025-0194-2681
Mass Comment Campaign sponsoring
organization unknown
9/8/25
32,622
EPA-HQ-OAR-2025-0194-2682
Mass Comment Campaign sponsoring
organization unknown
8/19/25
31,015
EPA-HQ-OAR-2025-0194-2683
Mass Comment Campaign sponsoring
organization unknown
8/21/25
29,666
EPA-HQ-OAR-2025-0194-2684
Mass Comment Campaign sponsoring
organization unknown
8/6/25
13,330
EPA-HQ-OAR-2025-0194-2685
Mass Comment Campaign sponsoring
organization unknown
9/6/25
12,581
EPA-HQ-OAR-2025-0194-2686
Mass Comment Campaign sponsoring
organization unknown
9/11/25
7214
EPA-HQ-OAR-2025-0194-2687
Mass Comment Campaign sponsoring
organization unknown
8/23/25
3109
EPA-HQ-OAR-2025-0194-2688
Mass Comment Campaign sponsoring
organization unknown
8/12/25
3231
EPA-HQ-OAR-2025-0194-2689
Mass Comment Campaign sponsoring
organization unknown
9/19/25
2976
EPA-HQ-OAR-2025-0194-2690
Mass Comment Campaign sponsoring
organization unknown
8/27/25
3332
EPA-HQ-OAR-2025-0194-2691
Mass Comment Campaign sponsoring
organization unknown
9/15/25
1920
EPA-HQ-OAR-2025-0194-2692
Mass Comment Campaign sponsoring
organization unknown
8/20/25
1123
EPA-HQ-OAR-2025-0194-2693
Mass Comment Campaign sponsoring
organization unknown
8/31/25
1002
EPA-HQ-OAR-2025-0194-2694
Mass Comment Campaign sponsoring
organization unknown
9/12/25
922
EPA-HQ-OAR-2025-0194-2695
Mass Comment Campaign sponsoring
organization unknown
9/9/25
874
EPA-HQ-OAR-2025-0194-2696
Mass Comment Campaign sponsoring
organization unknown
9/13/25
604
EPA-HQ-OAR-2025-0194-2697
Mass Comment Campaign sponsoring
organization unknown
9/11/25
576
EPA-HQ-OAR-2025-0194-2698
Mass Comment Campaign sponsoring
organization unknown
9/18/25
534
324
-------
Document ID
Commenter
Date
# Signatures
EPA-HQ-OAR-2025-0194-2699
Mass Comment Campaign sponsoring
organization unknown
9/8/25
476
EPA-HQ-OAR-2025-0194-2700
Mass Comment Campaign sponsoring
organization unknown
9/4/25
341
EPA-HQ-OAR-2025-0194-2701
Mass Comment Campaign sponsoring
organization unknown
9/12/25
287
EPA-HQ-OAR-2025-0194-2702
Mass Comment Campaign sponsoring
organization unknown
8/23/25
269
EPA-HQ-OAR-2025-0194-2703
Mass Comment Campaign sponsoring
organization unknown
9/15/25
257
EPA-HQ-OAR-2025-0194-2704
Mass Comment Campaign sponsoring
organization unknown
9/8/25
223
EPA-HQ-OAR-2025-0194-2705
Mass Comment Campaign sponsoring
organization unknown
9/4/25
194
EPA-HQ-OAR-2025-0194-2706
Mass Comment Campaign sponsoring
organization unknown
9/4/25
185
EPA-HQ-OAR-2025-0194-2707
Mass Comment Campaign sponsoring
organization unknown
9/16/25
170
EPA-HQ-OAR-2025-0194-2708
Mass Comment Campaign sponsoring
organization unknown
8/13/25
168
EPA-HQ-OAR-2025-0194-2709
Mass Comment Campaign sponsoring
organization unknown
9/19/25
141
EPA-HQ-OAR-2025-0194-2710
Mass Comment Campaign sponsoring
organization unknown
8/11/25
132
EPA-HQ-OAR-2025-0194-2711
Mass Comment Campaign sponsoring
organization unknown
9/11/25
114
EPA-HQ-OAR-2025-0194-2712
Mass Comment Campaign sponsoring
organization unknown
8/1/25
114
EPA-HQ-OAR-2025-0194-2713
Mass Comment Campaign sponsoring
organization unknown
8/12/25
89
EPA-HQ-OAR-2025-0194-2714
Mass Comment Campaign sponsoring
organization unknown
9/7/25
65
EPA-HQ-OAR-2025-0194-2715
Mass Comment Campaign sponsoring
organization unknown
9/13/25
63
EPA-HQ-OAR-2025-0194-2716
Mass Comment Campaign sponsoring
organization unknown
9/7/25
40
EPA-HQ-OAR-2025-0194-2717
Mass Comment Campaign sponsoring
organization unknown
8/6/25
38
EPA-HQ-OAR-2025-0194-2718
Mass Comment Campaign sponsoring
organization unknown
8/18/25
35
EPA-HQ-OAR-2025-0194-2719
Mass Comment Campaign sponsoring
organization unknown
9/11/25
29
EPA-HQ-OAR-2025-0194-2720
Mass Comment Campaign sponsoring
organization unknown
8/21/25
26
EPA-HQ-OAR-2025-0194-2721
Mass Comment Campaign sponsoring
organization unknown
9/12/25
25
EPA-HQ-OAR-2025-0194-2722
Mass Comment Campaign sponsoring
organization unknown
8/19/25
19
EPA-HQ-OAR-2025-0194-2723
Mass Comment Campaign sponsoring
organization unknown
7/31/25
18
EPA-HQ-OAR-2025-0194-2724
Mass Comment Campaign sponsoring
organization unknown
9/3/25
10
EPA-HQ-OAR-2025-0194-2725
Mass Comment Campaign Sponsoring
organization unknown
8/27/25
10
325
-------
Document ID
Commenter
Date
# Signatures
TOTAL SIGNATURES
533,99166
66 Total is 534,160, Less number of mass mailers (169), to remove double counting.
326
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