The U.S. Supreme Court issued two opinions that draw a clearer line between challenges to Environmental Protection Agency actions that belong in the District of Columbia Circuit and those that should be heard in regional appeals courts, a ruling that could curb forum shopping in environmental litigation. In a 7–2 opinion written by Justice Clarence Thomas in EPA v. Calumet Shreveport Refining, the Court held that small refineries contesting the agency’s denial of renewable-fuel standard exemptions must file in the D.C. Circuit because the EPA’s reasoning rested on determinations of nationwide scope. A separate 8–0 decision in Oklahoma v. EPA, also authored by Thomas, concluded that the EPA’s rejection of Oklahoma’s and Utah’s state ‘Good Neighbor’ ozone plans is predominantly fact-specific and therefore should be reviewed in the Tenth Circuit rather than in Washington. Justice Samuel Alito did not participate. Together, the rulings establish a two-step framework for deciding venue under the Clean Air Act: nationally applicable actions—or local actions based on nationwide determinations—go to the D.C. Circuit, while primarily local or regional decisions stay in regional courts. The venue issue will return to the Court next term after justices agreed earlier in the week to hear Chevron and Exxon Mobil’s bid to move Louisiana coastal-damage lawsuits into federal court.