On February 18, 2026 (91 Fed. Reg. 7686), the U.S. Environmental Protection Agency (EPA or Agency) issued a Final Rule rescinding its 2009 “Endangerment Finding” (74 Fed. Reg. 66496 (Dec. 15, 2009)), which concluded that six greenhouse gases (GHGs)—carbon dioxide, methane, nitrous oxide, hydrofluorocarbons, perfluorocarbons, and sulfur hexafluoride—taken in combination from new motor vehicles and engines (1) endanger both the public health and the public welfare of current and future generations, and (2) contribute to the GHG air pollution that endangers public health and welfare under Clean Air Act (CAA) section 202(a)(1).
As noted in the 2026 Final Rule, since EPA has rescinded the 2009 Endangerment Finding, the Agency no longer has the statutory authority under CAA section 202(a)(1) to prescribe or maintain GHG emission standards for new motor vehicles and engines and, as a result, repeals these standards. The Final Rule is effective on April 20, 2026.
Notably, EPA’s Final Rule only applies to GHG emission standards for new motor vehicles and engines; it does not address GHG emission standards that are in place for stationary sources.
The 2009 Endangerment Finding
CAA section 202(a) requires EPA to regulate emissions of any “air pollutant” from new motor vehicles and engines that “cause, or contribute to, air pollution which may reasonably be anticipated to endanger public health or welfare.” In the 2009 Endangerment Finding, EPA concluded that GHG emissions from motor vehicles and engines meet the criteria for regulation based primarily on assessments by the U.S. Global Climate Research Program, the Intergovernmental Panel on Climate Change, and the National Research Council. That is, EPA considered the “global” effects of GHG emissions on public health and welfare. As a result of EPA’s 2009 Endangerment Finding, the Agency promulgated emission standards and associated test procedures; averaging, banking, and trading requirements; reporting requirements; and fleet-average emission requirements for new motor vehicles and engines.
The 2026 Final Rule Rescinding the 2009 Endangerment Finding
In EPA’s Proposed Rule (90 Fed. Reg. 36288 (Aug. 1, 2025)), the Agency articulated a number of statutory and policy positions to support the proposed rescission of the 2009 Endangerment Finding:
- The term “air pollution” in CAA section 202(a)(1) is best read in context as referring to pollution that threatens public welfare through local or regional exposure, consistent with historical practice and principles of proximate cause, such that the EPA’s regulatory authority does not extend to global climate change concerns.
- The “major questions” doctrine applies to the question whether the EPA may decide the Nation’s policy response to global climate change concerns, and Congress did not clearly delegate that decision when it authorized the Agency to prescribe emission standards for new motor vehicles and engines.
- The 2009 Endangerment Finding departed from the CAA in additional ways by asserting “procedural discretion” to issue findings separately from the required standards and severing the question whether GHG emissions from motor vehicles and engines contribute to increases in global GHG concentrations from the question whether cumulative global GHG concentrations endanger public health and welfare.
- The EPA Administrator exercises his discretion under CAA section 202(a)(1) to issue a new finding that the conclusions reached in the 2009 Endangerment Finding are not supported by the scientific record, including because the EPA unreasonably compiled and analyzed the record in 2009 and because intervening climate change developments have cast significant doubt on the Endangerment Finding’s core premises and assumptions.
- There is no “requisite technology,” as required for emission standards to go into effect under CAA section 202(a)(2), that is capable of having a measurable impact on the global climate change concerns that were the basis of the 2009 Endangerment Finding.
- The Agency’s GHG regulatory program is futile because emissions from covered vehicles have a de minimis impact on global climate change concerns, and this consideration bears on the proper interpretation and implementation of CAA section 202(a)(1).
- The GHG emission standards harm public health and welfare on balance by increasing prices and decreasing consumer choice, thereby slowing the replacement of older vehicles that are less safe and emit a greater volume and variety of air pollutants.
As anticipated, there was a significant mass comment campaign by stakeholders in opposition to EPA’s Proposed Rule – roughly 572,000 written comments were submitted to the public docket, with the vast majority (534,000) being submitted in the form of 169 mass comment campaigns.
Although in the Proposed Rule EPA cited the Administrator’s discretion to rescind the 2009 Endangerment Finding based on the global climate modeling used to support it, in the Final Rule the Agency “walks back” this basis for rescission – stating “[a]lthough the Administrator continues to harbor concerns regarding the scientific determinations underlying the Endangerment Finding, the EPA has decided not to finalize this scientific alternative rationale at this time.”
Nonetheless, EPA relies on the remainder of the statutory, legal, and policy reasons articulated in the Proposed Rule to support its Final Rule. Notably, EPA relies on the Supreme Court’s 2024 decision ending Chevron deference (Loper Bright v. Raimondo, 603 U.S. 369 (2024)) (asserting EPA’s 2026 position is the “best read” of CAA section 202(a)(1)) and the 2022 decision concluding that EPA cannot utilize its statutory authority to take actions that decide major questions of policy (West Virginia v. EPA, 597 U.S. 697 (2022) (wherein the Supreme Court vacated EPA’s attempt to shift the power grid away from using fossil fuels through GHG standards for existing power plants)).
Path Forward
Three major questions result from EPA’s Final Rule: (1) the ability of states to impose GHG standards on new motor vehicles and engines; (2) the viability of common law claims related to GHG emissions from new motor vehicles and engines; and (3) the future of GHG regulations for stationary sources.
- Regarding the first question, EPA states that “whether we prescribe standards for GHG emissions from new motor vehicles or engines, CAA section 209(a) continues to apply by its own force to preempt State laws, regulations, and causes of action that adopt or attempt to enforce any standard relating to the control of emissions from new motor vehicles or engines.”
- Regarding the second question, EPA states the “CAA also continues to preempt state common-law claims and statutes that seek to regulate out-of-state emissions, independently of CAA section 209(a)’s express preemption provision for mobile-source emissions.” EPA provides more substance to its position in the Response to Comments document:
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. [] 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 using federal common law.
- Regarding the third question, although EPA’s Final Rule is only applicable to GHG emissions from new motor vehicles and engines, its rationale as to what constitutes an “air pollutant” is also relevant to stationary sources. It is unclear at this point whether EPA will more broadly attempt to reverse prior GHG emission standards for stationary sources. However, EPA has embarked on a rulemaking to repeal GHG emission standards for fossil fuel-fired electric generating units, citing rationale similar to that in the Final Rule (90 Fed. Reg. 25752 (June 17, 2025)).
There will certainly be litigation challenging the Final Rule. Under CAA section 307(b)(1), judicial review of the Final Rule is available only by filing a petition for review in the U.S. Court of Appeals for the District of Columbia Circuit by April 20, 2026.
about the author
Chris Leason is an environmental shareholder at Gallagher & Kennedy, focusing on regulatory compliance and civil enforcement defense in the areas of hazardous waste, toxic substances, chemical facility anti-terrorism standards, regulatory enforcement, rulemaking, litigation risk management, and due diligence audits.