Both sets of cases turned on a provision of the Clean Air Act anti-pollution law that designates the D.C. Circuit as the exclusive venue for cases over "nationally applicable" EPA actions and rules but leaves cases concerning only local agency actions to regional federal appeals courts.

Justices rebuke EPA over jurisdiction fight, ruling Utah and Oklahoma’s pollution cases belong in local — not national — court.

The unanimous ruling is about state implementation of standards for smog-forming pollution that crosses state lines.

The Supreme Court on Wednesday detailed a set of rules for when certain local actions by the Environmental Protection Agency (EPA) can be heard by regional courts or when they need to be heard at the D.