Equal Pay Act of 1963
In 1942, Republican congresswoman Winifred C. Stanley from Buffalo, N.Y. introduced H.R. 5056, Prohibiting Discrimination in Pay on Account of Sex, which did not pass at the time. The issue languished until 10 June 1963, when Congress passed the Equal Pay Act ("EPA" or the "Act") as an amendment to the Fair Labor Standards Act, to "prohibit discrimination on account of sex in the payment of wages by employers."
Equal Pay Act 1970
Once the employee has established that they are employed on 'equal work' with their comparator then they are entitled to 'equal pay' unless the employer proves that the difference in pay is genuinely due to a material factor which is not the difference in gender.