Fourteenth Amendment, Section 1:
All persons born or naturalized in the United States, and subject to the jurisdiction thereof, are citizens of the United States and of the State wherein they reside. No State shall make or enforce any law which shall abridge the privileges or immunities of citizens of the United States; nor shall any State deprive any person of life, liberty, or property, without due process of law; nor deny to any person within its jurisdiction the equal protection of the laws.
Objections to labor legislation on the ground that the limitation of particular regulations to specified industries was obnoxious to the Equal Protection Clause have been consistently overruled. 1 Statutes limiting hours of labor for employees in mines, smelters, 2 mills, factories, 3 or on public works 4 have been sustained. And a statute forbidding persons engaged in mining and manufacturing to issue orders for payment of labor unless redeemable at face value in cash was similarly held unobjectionable. 5 The exemption of mines employing fewer than ten persons from a law pertaining to measurement of coal to determine a miner’s wages is not unreasonable. 6 All corporations 7 or public service corporations 8 may be required to issue to employees who leave their service letters stating the nature of the service and the cause of leaving even though other employers are not so required.
Industries may be classified in a workers’ compensation act according to the respective hazards of each, 9 and the exemption of farm laborers and domestic servants does not render such an act invalid. 10 A statute providing that no person shall be denied opportunity for employment because he is not a member of a labor union does not offend the Equal Protection Clause. 11 At a time when protective labor legislation generally was falling under
liberty of contract applications of the Due Process Clause, the Court generally approved protective legislation directed solely to women workers, 12 and this solicitude continued into present times in the approval of laws that were more questionable, 13 but passage of the sex discrimination provision of the Civil Rights Act of 1964 has generally called into question all such protective legislation addressed solely to women. 14