Lochner v. New York

Majority reasoning

The majority, led by Justice Peckham, held that the general right to make contracts about one's business, including labor contracts, is part of the "liberty" protected by the Fourteenth Amendment's Due Process Clause. While states have police powers to protect health, safety, and morals, those powers have limits, and a law restricting contract rights must have a direct and substantial relation to a legitimate health purpose, not just a remote or speculative one. The Court found that baking is not an unusually unhealthy occupation compared to many other trades, and that if the state's reasoning were accepted, virtually any occupation's hours could be regulated, effectively eliminating the constitutional protection for liberty of contract. The majority concluded that the true purpose of the law appeared to be regulating labor conditions generally rather than protecting health, which is not a valid basis for interfering with contract rights under their reasoning.

Dissent reasoning

Justice Harlan, joined by Justices White and Day, argued that courts should defer to legislatures on police power questions unless a law is plainly and palpably unconstitutional beyond all reasonable doubt, and that the burden of proving unconstitutionality rests with the challenger. Harlan cited medical and statistical evidence, including expert writings on the health hazards of baking (flour dust, heat, night work), to argue there was a real and substantial connection between the law and worker health, meaning the statute should be upheld. Separately, Justice Holmes argued that the Constitution does not enact any particular economic theory, and that the majority was improperly substituting its own economic philosophy for that of the New York legislature. Holmes contended that a law should only be struck down if a fair and rational person could not possibly view it as reasonable, and that many reasonable people supported such labor regulations as legitimate health or welfare measures.