On Tuesday, EPA proposed to repeal its 2009 Endangerment Finding (Repeal Proposal). That’s a big deal, with expansive implications. The 2009 Endangerment Finding determined six greenhouse gases (GHG) are air pollutants that endanger public health and welfare, and subsequently allowed EPA to regulate GHG emissions from motor vehicles. EPA’s Repeal Proposal, which relies heavily on recent Supreme Court decisions in Loper Bright Enterprises v. Raimondo and West Virginia v. EPA, is an early product of the January 2025 Executive Order Unleashing American Energy specifically referencing the finding. It’s also an outgrowth of the February 2025 Executive Order Ensuring Lawful Governance, which directed agencies to review regulations for consistency with the Constitution and the “best reading of the authorizing statute.”

On its face, this proposal is limited to EPA’s findings under section 202(a) of the Clean Air Act to regulate mobile sources of pollution. But it’s not so narrow. EPA has referred to and relied on the 2009 Endangerment Finding to regulate other sources of GHGs using its Clean Air Act authority. Repeal of this foundational Finding is like removing a critical block in the game of Jenga. As EPA moves forward with the reconsideration or repeal of various standards, including methane standards for oil and gas and carbon pollution standards for fossil-fuel fired power plants, those regulations are on increasingly unstable footing without the 2009 Endangerment Finding.

Key Takeaways

• EPA’s Repeal Proposal focuses on the auto industry, but signals a broader deregulatory effort. In the past, EPA has pointed to this foundational legal Finding to regulate GHG emissions across multiple sectors, including oil and gas, power plants, and commercial aviation.
• Litigation over EPA’s ultimate decision is all but guaranteed. Comments submitted in this rulemaking may build the record for far-reaching decisions.
• Staying aware and involved in the rulemaking process is essential to a cohesive long term legal strategy. 

Why the Endangerment Finding Is the Critical Block: Sector Impacts and Legal Uncertainty

The proposal to repeal the 2009 Endangerment Finding represents a dramatic shift in the foundation of U.S. climate policy and regulatory authority. The Finding, issued in the wake of the Supreme Court’s 2007 decision in Massachusetts v. EPA, provided the prerequisite for EPA’s regulation of GHG emissions from motor vehicles under section 202(a) of the Clean Air Act.

Over the years, EPA has used the Finding under section 202(a) as a building block for regulations of other sectors under different provisions of the Clean Air Act. For example, EPA relied on the Finding, and its cited science, in the 2015 methane standards for oil and gas, 2016 finding that GHG emissions from aircraft similarly endanger public health and welfare, 2021 (and subsequent) regulations to phasedown and regulate hydrofluorocarbons, and 2024 carbon pollution standards for fossil-fuel fired power plants. The EPA’s recent proposal rejects the essential underpinnings of the 2009 decision. While EPA’s proposal purports to be limited to motor vehicles, its questions and rationale will likely further destabilize a multitude of other regulations too. 

What’s in the Proposal

In short, in the Repeal Proposal, EPA is proposing to repeal all GHG emission standards for light-duty, medium-duty, and heavy-duty vehicles and engines. EPA has offered three potential pathways to this result, all of which illuminate the Agency’s overall policy and likely approach to climate regulations still on the books. 

As the primary proposal, EPA asserts that section 202(a) doesn’t authorize standards based on global climate change or allow EPA to make an endangerment finding without simultaneously issuing emission standards. Here, EPA cites to Loper Bright, West Virginia, and Utility Air Regulatory Group v. EPA, positing that global climate change is a major question that Congress did not authorize EPA to regulate. EPA proposes that the best reading of section 202(a) is that Congress only permits EPA to regulate pollutants that are themselves dangerous in localized concentrations (or that interact with airborne constituents to then become dangerous—like SO2 and acid rain). That GHG emissions have “indirect” impacts means they may not be “air pollution” in EPA’s view. 

As an alternative, EPA proposes to repeal the 2009 endangerment finding and resulting motor vehicle standards because the finding analyzed endangerment and contribution in an unreasonable manner. Relying on a draft report issued this month by the Department of Energy’s Climate Working Group, EPA posits that reality has not borne out the temperature increases, heat waves, sea level rise, or extreme weather events prognosticated in the 2009 finding.

Finally, as its third option, EPA proposes that independent of any action on the endangerment finding, the GHG standards for motor vehicles should be repealed because there is no “requisite technology” to reduce GHG emissions to zero from vehicles because it wouldn’t measurably impact GHG concentrations in the atmosphere or rate of global climate change. Essentially that the Clean Air Act’s tools here won’t have a material impact on global emissions.

EPA repeatedly make statements that attempt to limit this proposal to motor vehicles and flags that other regulations for other sectors will be handled in separate regulatory efforts. That said, much of EPA’s rationale here, especially pronouncements regarding global climate policy as a major question, will transfer easily to those efforts. 
 

What Happens Next

• The comment period for EPA’s proposal ends on September 21, 2025. Comments received during this period will form the record for EPA’s ultimate decision and any resulting litigation. Entities outside of the auto sector should consider getting involved given the potential ripple effects of the Agency’s reasoning, or at least stay informed.
• With therevocation of the California waiver and the repeal of the 2009 Endangerment Finding, EPA has dismantled the state and federal regulation of GHG emissions from cars and light duty trucks.  However, fuel economy standards issued by NHTSA remain in place. 
• We might see enhanced regulatory activity in some states inclined to impose stricter climate regulations on stationary sources within their jurisdiction. 
• EPA signaled in this proposal that it will handle GHG standards in other sectors in separate rulemakings.  However, it is clear that this proposal is a precursor to additional deregulatory action.