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Summary of Action 

Enacting what it called the “single largest deregulatory action in U.S. history”, on February 12, 2026, U.S. Environmental Protection Agency (EPA) Administrator Lee Zeldin finalized a rulemaking that rescinds a 2009 rulemaking known as the “Endangerment Finding” for greenhouse gas (GHG) emissions. The February 12 rulemaking also substantially revises the federal mobile source regulations to eliminate all federal GHG emission standards established since 2009 for motor vehicles and certain other mobile source engines. This reversal on climate policy creates uncertainty for mobile source manufacturers who made significant investments since 2009 to comply with limits on greenhouse gases, as well as other industries subject to greenhouse gas limits not explicitly rescinded by the rule.

After the Supreme Court determined in Massachusetts v. EPA, 549 U.S. 497 (2007) that four GHGs emitted by mobile source engines were “air pollutants” under section 302(g) of the Clean Air Act (CAA), EPA issued the rulemaking for “Endangerment and Cause or Contribute Findings for Greenhouse Gases Under Section 202(a) of the Clean Air Act” (the Endangerment Finding). Between 2010 and 2024, EPA issued a series of rulemakings that expanded GHG emissions standards for new motor vehicles and motor vehicle engines, including rules designed to incentivize the adoption of electric vehicles. 

The February 12 rulemaking removes all obligations for the measurement, control, and reporting of GHG emissions for all highway engines and vehicles, including for prior model years. To explain this policy reversal, EPA stated that it has carefully considered and reevaluated the legal foundation of the 2009 Endangerment Finding, the text of the CAA, and the Endangerment Finding’s legality in light of subsequent legal developments and court decisions—specifically, the Supreme Court’s decisions in Utility Air Regulatory Group v. EPA, West Virginia v. EPA, and Loper Bright Enters. v. Raimondo. As a result of that review, the Trump/Zeldin EPA has concluded that, contrary to the Endangerment Finding, the CAA does not authorize EPA to promulgate motor vehicle emission standards for the purpose of addressing global climate change, and that EPA cannot retain GHG emission standards for mobile sources.

It is important to note that the February 12 rulemaking is limited to the Endangerment Finding and mobile source GHG regulations. It does not remove other automotive emission limits for criteria pollutants (like nitrogen oxides) or for air toxics. It also does not affect NHTSA’s vehicle fuel economy (CAFÉ) standards. Finally, it does not repeal any greenhouse gas emission limits applicable to stationary sources under the Prevention of Significant Deterioration (PSD) or New Source Performance Standards (NSPS) CAA programs. 

The rule takes effect 60 days after it is published in the Federal Register. That said, the repeal of the Endangerment Finding is almost certain to be challenged by environmental organizations and states focused on continuing efforts to electrify transportation and reduce global emissions generally. We will monitor the publication of and challenges to the rule, as well as any related rulemakings that seek to repeal other greenhouse gas regulations (such as those applicable under the PSD and NSPS programs). If you have questions about the February 12 rulemaking or its provisions, please contact Amanda Beggs or Pete Tomasi.