24 states sue EPA over repeal of greenhouse gas endangerment finding

A coalition of 24 states, 10 cities, and 5 counties filed suit in the D.C. Circuit Court of Appeals on March 19, 2026, challenging the Trump EPA's rescission of the 2009 Endangerment Finding. The 2009 finding — which declared greenhouse gases a threat to public health — was the legal foundation for all EPA climate regulations under the Clean Air Act. EPA Administrator Lee Zeldin and Trump framed the repeal as the largest deregulatory action in U.S. history. California, Connecticut, Massachusetts, and New York co-led the suit.