In the 1973 case Corning Glass Works v. Brennan, Secretary of Labor, the U.S. Supreme Court ruled in favor of Brennan and against Corning Glass Works on a wage discrimination issue based on gender under the Equal Pay Act of 1963. The company had been paying male night shift inspectors more than their female counterparts working during day shifts for performing essentially identical tasks until June 1966 when it equalized day and night wages for new employees while continuing to pay higher rates to men who were already working nights before that date. The court held that this constituted an unlawful practice as per the act since there was no factor other than sex justifying differential payment between men and women doing similar work at different times of day or night.

In the dissenting opinion for Corning Glass Works v. Brennan, Justice William O. Douglas argued that the majority's interpretation of "work performed under similar working conditions" was too narrow and failed to consider the broader social context in which wage discrimination occurs. He contended that by focusing solely on physical similarities between jobs, such as effort and skill required, without considering other factors like societal attitudes towards gender roles or historical patterns of wage disparity, the court missed an opportunity to address systemic inequality in pay structures. Furthermore, he criticized the majority's decision for allowing employers to justify unequal wages based on market forces or job classifications established prior to passage of Equal Pay Act (EPA). In his view, this undermined EPA’s purpose - eliminating wage discrimination based on sex.