The Equal Pay Act, passed in 1963, was the first law to address gender inequality in the workplace and one of the first laws to benefit women explicitly since they gained the right to vote earlier in the century. The Equal Pay Act guaranteed equal pay for equal work for men and women. For the act to take effect, men and women must be employed under similar working conditions, and equal is defined as “equal skill, effort and responsibility.” Overtime and travel are included among the provisions of the act.

The Equal Pay Act is part of the Fair Labor Standards Act, although it is unlike the other parts of the act in that there are no exceptions for executive, administrative, professional employees, or outside salespeople. But the Equal Pay Act contains the same business exceptions as the Fair Labor Standards Act and covers only employees “engaged in commerce.” In practice, this law applies to vast majority of businesses in the country.

There are four affirmative defenses to the Equal Pay Act: merit, production, seniority, and “factor other than sex.” The most litigated of these defenses is the “factor other than sex” because of the ambiguous nature of the clause. For example, prior wages, profitability of the company, and evaluation of a personal interview have all been held to be a factor other than sex justifying pay discrepancies between men and women under the Equal Pay Act.