Ohio v. Environmental Protection Agency, 603 U.S. 279 (2024), is a United States Supreme Court case regarding the Clean Air Act.

The EPA argued that the plan contained important public benefits that if halted would cause delays in improving air quality that could be harmful.

Neil Gorsuch delivered the opinion of the court, which John Roberts, Samuel Alito, Clarence Thomas, and Brett Kavanaugh joined.

They applied the Clean Air Act's section that allows a court to reverse a federal implementation plan if it is "arbitrary or capricious" and found in favor of Ohio.

[4][5] Amy Coney Barrett delivered the dissent, joined by Sonia Sotomayor, Elena Kagan, and Ketanji Brown Jackson.