A coalition of over 20 U.S. states, joined by cities and counties, is challenging the U.S. Environmental Protection Agency's (EPA) decision to overturn its 2009 Greenhouse Gas Endangerment Finding, a foundational rule for federal climate regulations.

• The EPA's rescission, finalized on February 12, 2026, is described as the "single largest deregulatory action in U.S. history," projecting cost savings of over $1.3 trillion.
• Key organizations involved include the plaintiff coalition, the EPA, and potentially the Supreme Court.
• The plaintiffs argue the rollback ignores scientific evidence and violates the Clean Air Act and the Administrative Procedure Act.