EPA proposes reconsidering the 2009 GHG endangerment finding

EPA offers a primary and alternative bases for its proposal, as follows:

• EPA’s primary argument is that it does not have authority under CAA section 202(a) to prescribe emission standards based on global climate change concerns and therefore the agency proposes to rescind the 2009 Endangerment Finding.
  • EPA proposes to reinterpret the terms “air pollutant” and “air pollution” under CAA section 202(a) to refer to local or regional exposure to dangerous air pollution, rather than a global approach. EPA asserts that the 2009 analysis of six “well-mixed GHGs” and any resulting global climate change concerns involve causal relationships that are too uncertain, remote, and confounded by other factors to meet the “cause” and “contribute” criteria under CAA section 202(a).
  • Relying on recent Supreme Court precedent from Loper Bright Enterprises v. Raimondo, 603 U.S. 369 (2024), West Virginia v. EPA, 597 U.S. 697 (2022), and Utility Air Regulatory Group v. EPA, 573 U.S. 302 (2014) (among others), EPA asserts that the CAA is silent or ambiguous with regard to addressing global climate change and, as a result, EPA lacks the “clear congressional authorization” required under the major questions doctrine.
  • EPA also argues that the 2009 Endangerment Finding inappropriately separated the endangerment and standard-setting proceedings. As a result, EPA proposes that the endangerment finding and standard setting process must occur together. In doing so, EPA asserts that CAA section 202(a) requires the Administrator to find that an air pollutant must cause, or contribute to, air pollution which endangers public health or welfare, “without relying on emissions from stationary or other sources regulated by distinction CAA provisions.”
• As an alternative bases, EPA proposes to rescind the 2009 Endangerment Finding because its original analysis of the scientific record and data was unreasonable and subsequent legal and scientific developments “cast significant doubt on the reliability of the findings.”
• EPA also offered an alternative bases for its proposal to repeal all GHG emission standards (even if the Endangerment Finding were to remain in place) because there is no “requisite technology” for emission control from motor vehicles and engines that can address global climate change concerns.
  • According to EPA, there is no “requisite technology” because even reducing GHG emissions from new motor vehicles and engines to zero would “not have a scientifically measurable impact on global GHG concentrations and climate trends.”
  • EPA asserts that any “requisite technology” would, at a minimum, require a full shift from internal combustion engines to electric vehicles, which runs contrary to the “generation-shifting” “fuel switching” approach deemed illegal in West Virginia.
  • EPA also proposes that, on balance, GHG standards harm the public health and welfare by decreasing consumer choice, increasing prices, and keeping older (and less safe/efficient) cars on the road for longer.

The proposal would repeal all GHG emission standards for motor vehicles and engines (both light- and heavy-duty) as well as all related test procedures, reporting requirements, fleet-average emission requirements, and credit average, banking, and trading (ABT) provisions. In short, the proposal would “remove all existing regulations that require new motor vehicles and engines to measure, report, or comply with GHG emission standards.” The proposal would apply to all model years of vehicles and engines, including those manufactured prior to the effective date of any final rule.

EPA originally issued the Endangerment Finding in 2009 during the Obama Administration in response to the Supreme Court’s 2007 decision in Massachusetts v. EPA, 549 U.S. 497 (2007). The Supreme Court case arose after states petitioned EPA and requested that the agency regulate CO₂ and other greenhouse gas emissions from new motor vehicles. The Endangerment Finding contained two key findings regarding the regulation of GHGs under the Clean Air Act (CAA: (1) “elevated concentrations of [GHGs] . . . may reasonably be anticipated to endanger the public health”; and (2) “emissions of the well-mixed [GHGs] from new motor vehicles contribute to the air pollution that may reasonably be anticipated to endanger public health and welfare . . . .” See EPA Final Rule, Endangerment and Cause or Contribute Findings for Greenhouse Gases Under Section 202(a) of the Clean Air Act, 74 Fed. Reg. 66,496), 66,516, 66,537 (Dec. 15, 2009) (emphases added). EPA now argues that the 2009 Endangerment Finding misconstrues the Supreme Court’s decision in Massachusetts, which the agency now proposes does not require a finding that GHGs are subject to regulation under the CAA. EPA now asserts that, consistent with the holding in Massachusetts, regardless of whether individual GHGs are “air pollutants” under the broad, CAA-wide definition, they must also meet the CAA statutory standard for regulation under 202(a) because they “cause” or “contribute” to air pollution that endangers the public health or welfare.

Today’s proposed rule follows President Trump’s Executive Order (EO) 14154 “Unleashing American Energy” which directed EPA to submit joint recommendations to the Director of the Office of Management and Budget (OMB) “on the legality and continuing applicability of the Administrator’s findings”. 90 Fed. Reg. 8353, 8357 (Jan. 20, 2025). EPA had previewed the reconsideration of the Endangerment Finding in the March 12, 2025 “Deregulatory Action” announcement. See Press Release, EPA Launches Biggest Deregulatory Action in U.S. History (March 12, 2025).

While the Administration has not set a timeline to finalize the proposed rule, we anticipate EPA will target late 2025, with legal challenges undoubtedly following shortly after. If finalized, the rule will have significant implications for the GHG credit market (including potentially prior and current credit sales) and raise questions within the industry regarding past enforcement and the potential for future/retroactive enforcement. Additionally, EPA asserts that its proposed action does not impact Federal preemption with respect to GHGs, including for motor vehicle and engine emission standards under the CAA or under EPCA and EISA. According to EPA’s proposal, the CAA would continue to preempt any state or local standard relating to the control of emissions from new motor vehicles and engines, including GHG emissions. Notably, EPA did not propose to modify regulations for criteria emissions standards, CAFE testing, or fuel economy labeling requirements. EPA indicated that it is reconsidering in separate rulemakings additional endangerment findings and GHG emission standards issued under distinct provisions of the CAA.

The proposal is scheduled for publication in the Federal Register tomorrow (August 1, 2025), with public comments due within 45 days (i.e., September 15, 2025). EPA will also plan to hold virtual public hearings on August 19-20, 2025. EPA has noted specific aspects of the proposal on which it seeks comment; however, the Agency has indicated it will respond to all comments within the scope of the proposal. Additional materials related to the proposed rule and docket (EPA-HQ-OAR-2025-0194) are available on EPA’s website.

Authored by Joanne Rotondi, Hannah Graae, and Allisa Newman.