Overview

• The Supreme Court’s 8-0 ruling bars the EPA from defending its denials of individual state implementation plans in the D.C. Circuit and directs those cases to regional courts.
• Justice Clarence Thomas wrote that bundling multiple SIP disapprovals in a single Federal Register notice does not transform them into a national action.
• The opinion establishes a venue test distinguishing localized EPA decisions from nationwide rules eligible for review in the D.C. Circuit.
• The dispute originated from the EPA’s 2023 rejection of 21 states’ plans under the Clean Air Act’s Good Neighbor provision.
• The case is now set to proceed in the 10th Circuit Court of Appeals, a move that could diversify judicial review of federal regulations.