Mr. Justice FRANKFURTER dissenting.
This case does not present one of those large constitutional issues which, because they are so largely abstract, have throughout its history so often divided the Court. The controversy, as I understand it, is concerned with the proper administration of a law in which Congress has recognized the interests of the States as well as of the United States and has entrusted the proper adjustment of these nation-State relations to the interrelated functions of the Federal Power Commission and the courts.
We are all agreed that Congress has the constitutional power to promote a comprehensive development of the nation's water resources and that it has exercised its authority by the Federal Power Act. 41 Stat. 1063, 49 Stat. 838, 16 U.S.C. § 791a et seq., 16 U.S.C.A. § 791a et seq. See United States v. Chandler-Dunbar Water Power Co., 229 U.S. 53, 33 S.Ct. 667, 57 L.Ed. 1063; State of New Jersey v. Sargent, 269 U.S. 328, 46 S.Ct. 122, 70 L.Ed. 289; United States v. Appalachian Electric Power Co., 311 U.S. 377, 61 S.Ct. 291, 85 L.Ed. 243. And in view of Congress' power, of course this enactment overrides all State legislation in conflict with it. But the national policy for water power development formulate by the Federal Power Act explicitly recognizes regard for certain interests of the States as part of that national policy. This does not imply that general, uncritical notions about so-called 'States' rights' are to be read into what Congress has written. It does mean that we must adhere to the express Congressional mandate that the public interest which underlies the Federal Power Act involves the protection of particular matters of intimate concern to the people of the States in which proposed projects requiring the sanction of the Federal Power Commission are to be located. By § 9(b) of the Act, 41 Stat. 1063, 1068, 16 U.S.C. § 802(b), 16 U.S.C.A. § 802(b) Congress explicitly required that before the Commission can issue a license for the construction of a hydroelectric development, such as the proposed project of the petitioner, the Commission must have 'satisfactory evidence that the applicant has complied with the requirements of the laws of the State' in reference to the matters enumerated.
Whether the Commission has such 'satisfactory evidence' necessarily depends upon what the requirements of State law are. In turn, what the requirements of State law are often depends upon the appropriate but unsettled construction of State law. And so, the Commission may well be confronted, as it was in this case, with the necessity of determining what the State law requires before it can determine whether the applicant has satisfied it, and, therefore, whether the condition for exercising the Commission's power has been fulfilled.