In 1963, Congress passed the Equal Pay Act, which made it illegal for employers to pay women lower wages than men for equal work on jobs requiring the same skill, effort and responsibility. The act provides a cause of action for an employee to directly sue for damages.

Congress passed the Civil Rights Act the next year. It includes Title VII, which protects discrimination in employment based on protected class status, such as age, race or gender. This act prohibits discrimination in employment based on sex, and is also used in wage discrimination claims.