United States labor law
Since the Civil Rights Act of 1964, all employing entities and labor unions have a duty to treat employees equally, without discrimination based on "race, color, religion, sex, or national origin." There are separate rules for sex discrimination in pay under the Equal Pay Act of 1963. Additional groups with "protected status" were added by the Age Discrimination in Employment Act of 1967 and the Americans with Disabilities Act of 1990. There is no federal law banning all sexual orientation or identity discrimination, but 22 states had passed laws by 2016. These equality laws generally prevent discrimination in hiring, terms of employment, and make discharge because of a protected characteristic unlawful. There is no federal law against unjust discharge, and most states also have no law with full protection against wrongful termination of employment. Collective agreements made by labor unions and some individual contracts require people are only discharged for a "just cause". The Worker Adjustment and Retraining Notification Act of 1988 requires employing entities give 60 days notice if more than 50 or one third of the workforce may lose their jobs. Federal law has aimed to reach full employment through monetary policy and spending on infrastructure. Trade policy has attempted to put labor rights in international agreements, to ensure open markets in a global economy do not undermine fair and full employment.
Bennett Amendment
The Supreme Court of the United States first examined the question of the impact of the Bennett Amendment in the 1981 case "County of Washington v. Gunther", 452 U.S. 161. The case originated in 1974 in Oregon when a group of four female county prison guards sued the County of Washington for unequal wages, alleging that their pay was less than that of male guards for no reason other than sexual discrimination. The district court disagreed, finding that male guards were responsible for overseeing more prisoners and also that female guards spent some of their time in clerical tasks, but also found as a matter of law that a sex-based wage discrimination claim cannot be brought under Title VII unless it satisfies the equal work standard of the Equal Pay Act of 1963.