EPA Proposes Repealing the 2009 Endangerment Finding, the Legal Basis for U.S. Climate Rules

On July 29, 2025, the Environmental Protection Agency proposed rescinding its 2009 endangerment finding - the determination that greenhouse gases endanger public health and welfare, and the legal predicate for every federal climate rule under the Clean Air Act - along with all greenhouse-gas emission standards for cars and trucks. Administrator Lee Zeldin, who described the package as the largest deregulatory action in U.S. history, argued the emission standards themselves were the real threat to Americans' livelihoods. EPA's primary theory is that carbon dioxide does not fit the Clean Air Act's concept of "air pollution"; in the alternative it argues the record no longer supports the finding, relying in part on a report by scientists who reject the mainstream climate consensus. Standards on direct health harms such as particulates, and fuel-economy labeling, would remain.

The 2009 finding followed Massachusetts v. EPA (2007), in which the Supreme Court held greenhouse gases are air pollutants under the Clean Air Act. Repealing it would remove the statutory hook for vehicle, power-plant and other greenhouse-gas rules at once.

The proposal is not final. EPA opened a comment period through September 21, 2025, with a hearing in August. Litigation over any final rule was widely anticipated.