Prior to the enactment of the Civil Rights Act of 1964 (the Civil Rights Act), 42 U.S.C. § 2000e et seq., Duke Power Co. (Duke) (defendant) maintained a policy of open discrimination against black employees. Black employees were categorically excluded from all but one of Duke’s departments—the labor department, in which the highest paid employee earned less than the lowest paid employee in any other department. In 1955, Duke began requiring a high school degree for placement in any department other than labor and for transfer to any of the more desirable departments. Beginning on July 2, 1965, the date on which the Civil Rights Act went in to effect, Duke added additional requirements. To be placed in any department other than labor or to be transferred to any inside department, Duke required passage of two aptitude tests in addition to the high school degree requirement. The tests purportedly measured general intelligence but had no relation to job-performance ability. A number of black employees (plaintiffs) challenged the policy under Title VII of the Civil Rights Act. Both the district court and court of appeals held that Duke’s policies reflected no discriminatory purpose and had been applied equally to black and white employees. The court of appeals rejected the claim that because, in practice, the tests excluded a substantially disproportionate number of black employees, it violated Title VII. The plaintiffs petitioned for review by the United States Supreme Court.