In the case of County of Washington, Oregon v. Gunther et al., 1980, the U.S. Supreme Court ruled that female prison guards who were paid less than male counterparts for doing substantially similar work could sue for sex discrimination under Title VII of the Civil Rights Act. The plaintiffs argued that they performed jobs requiring equal skill, effort and responsibility as their male colleagues but received lower pay due to gender-based wage discrimination. The county contended that a claim could not be made unless it was proven that men and women were performing identical tasks in their roles - an interpretation based on the Equal Pay Act (EPA). However, this argument was rejected by the court which held a broader view on what constituted 'equal work'. This landmark decision expanded protections against wage discrimination beyond just those situations where men and women are doing exactly same job; it also included cases where different jobs may still require comparable skills or responsibilities.

In the dissenting opinion for County of Washington, Oregon v. Gunther et al., Justice Rehnquist argued that the majority's interpretation of Title VII was incorrect and overly broad. He contended that Congress intended to prohibit only wage discrimination based on sex where men and women perform equal work under similar conditions, not in cases where their jobs are merely comparable but not identical. The Equal Pay Act already addressed this issue by requiring equal pay for equal work regardless of gender; thus, he believed it unnecessary to extend Title VII protections beyond its original scope. He also expressed concern over potential difficulties in implementing such a wide-ranging standard as comparability rather than equality of work due to subjective judgments about job worth which could lead to endless litigation.