On August 1, 2025, the U.S. Environmental Protection Agency (EPA) proposed to rescind the 2009 Endangerment Finding, a scientific determination that greenhouse gas (GHG) emissions endanger public health and welfare. The Endangerment Finding has served for more than a decade as the statutory basis for regulating carbon dioxide and other GHGs from mobile sources following a 2007 Supreme Court ruling that such emissions qualify as air pollutants under the Clean Air Act.
The proposal, officially titled Reconsideration of 2009 Endangerment Finding and Greenhouse Gas Vehicle Standards, would repeal all existing GHG emission standards for light-, medium-, and heavy-duty vehicles that rely on the finding.
In its rulemaking, the agency argues that Section 202(a) was not intended to authorize regulation based on global climate change impacts. EPA said the provision was designed to address air pollutants with localized or regional effects, not “well-mixed” GHGs that are globally dispersed. The agency also questioned whether the scientific and technological record supports continued federal regulation of vehicle greenhouse gas emissions.
If finalized, the repeal would eliminate the statutory predicate for nearly all federal GHG regulation for mobile sources and could spill into other regulatory domains, including stationary sources, power plants, and oil and gas facilities, where EPA has issued analogous findings.
The proposal could also leave a regulatory gap, shifting responsibility to states or creating a fragmented policy landscape if federal authority is curtailed. Legal observers expect that any final withdrawal of the finding would face immediate litigation, focusing on both EPA’s interpretation of the Clean Air Act and its justification for reversing a long-standing scientific conclusion.
Industry and environmental reaction
Industry groups, including automotive manufacturers, have urged EPA to revise or recalibrate greenhouse gas standards to reflect changing market conditions rather than eliminate the regulatory framework entirely.
Environmental and public health advocates argue that the EPA lacks new scientific evidence to justify overturning the original finding and that rescission would undermine protections for climate-vulnerable communities. Others have warned that removing the federal regulatory floor will erode long-term investment certainty and compound climate risk across sectors.
Next Steps
The public comment period on the proposal is scheduled to remain open through mid-September 2025. The agency will review comments before issuing a final rule, which is likely to become a focal point for litigation and possible Congressional intervention.
A final decision on the repeal has significant implications for California’s regulatory strategy, including the state’s coordination with federal mobile source standards and its broader climate targets under SB 32 and AB 197.