Final answer:
The law that protects men and women who perform substantially equal work in the same establishment from sex-based wage discrimination is the Equal Pay Act of 1963 (EPA).
Step-by-step explanation:
The law that protects men and women who perform substantially equal work in the same establishment from sex-based wage discrimination is the Equal Pay Act of 1963 (EPA). This law requires employers to pay equal wages to employees of different genders who are performing equal work, in terms of skill, effort, and responsibility, under similar working conditions.
The EPA aims to eliminate wage disparities based on gender by ensuring that employees are not paid lower wages based on their gender.
Despite the EPA, persistent inequities in earnings between men and women still exist, but the law provides a legal framework for individuals to address sex-based wage discrimination.