Hancock v. Train

The question for decision in this case is whether a State whose federally approved implementation plan forbids an air contaminant source to operate without a state permit may require existing federally owned or operated installations to secure such a permit. The case presents an issue of statutory construction requiring examination of the Clean Air Act, as amended, 42 U. S. C. § 1857 et seq., and its legislative history in light of established constitutional principles governing the determination of whether and the extent to which federal installations have been subjected to state regulation.…