In 1905 the U.S. Supreme Court struck down a New York law that limited work in bakeries to ten hours a day and sixty hours a week. The case is Lochner v. New York, and the vote was five to four.
Justice Rufus Peckham wrote for the majority. Laws “limiting the hours in which grown and intelligent men may labor to earn their living, are mere meddlesome interferences with the rights of the individual.” Justice Oliver Wendell Holmes dissented: “The 14th Amendment does not enact Mr. Herbert Spencer’s Social Statics.”
The Court’s 1937 decision in West Coast Hotel Co. v. Parrish signaled the end of this view. Federal law today still sets no limit on hours for adults.