Control over interstate commerce belongs entirely to Congress. The Fair Labor Standards Act of 1938 is constitutional under the Commerce Clause because it prevents the states from lowering labor standards to gain commercial advantages. Decided February 3, 1941 (argued 1940). Opinion of the Court: Harlan F. Stone → go there Topic: Federalism. United States v. Darby Lumber Co., 312 U.S. 100 (1941), was a case in which the United States Supreme Court upheld the Fair Labor Standards Act of 1938, holding that the U.S. Congress had the power under the Commerce Clause to regulate employment conditions. The unanimous decision of the Court in this case overturned Hammer v. Dagenhart, 247 U.S. 251 (1918), limited the application of Carter v. Carter Coal Company, 298 U.S. 238 (1936), and confirmed the underlying legality of minimum wages held in West Coast Hotel Co. v. Parrish, 300 U.S. 379 (1937). Wiki link