The common legal opinion of federal child labor regulation reversed in the 1930s. Congress passed the Fair Labor Standards Act in 1938 regulating the employment of those under 16 or 18 years of age. The Supreme Court ruled unanimously in favor of that law in "United States v. Darby Lumber Co." (1941), which overturned "Hammer v. Dagenhart" (one of the key decisions that had motivated those in favor of the Child Labor Amendment). After this shift, the amendment has been described as "moot" and effectively part of the Constitution; the movement for it had concluded.