In the case of Western Air Lines, Inc. v. Criswell et al., 1984, the U.S. Supreme Court ruled that an airline's mandatory retirement age policy for flight engineers was not justified under the Age Discrimination in Employment Act (ADEA). The court held that Western Air Lines failed to prove its claim that safety concerns necessitated a rule forcing flight engineers to retire at age 60. The ADEA requires employers to demonstrate any such policies are based on "reasonable factors other than age" or constitute a "bona fide occupational qualification." In this instance, the court found no evidence suggesting all or nearly all individuals over 60 were unable to perform their duties safely as flight engineers nor did it find facts showing it would be impossible or highly impractical for Western Airlines to assess fitness on an individualized basis.

In the dissenting opinion for Western Air Lines, Inc. v. Criswell et al., Justice Thurgood Marshall argued that the Age Discrimination in Employment Act (ADEA) was designed to protect older workers from arbitrary age discrimination and should be interpreted broadly to achieve this purpose. He disagreed with the majority's view that an employer could justify a discriminatory policy by showing it was reasonably necessary for business operations, arguing instead that employers should have to demonstrate there are no alternative policies which would accomplish their goals without discriminating on basis of age. Furthermore, he criticized the majority’s reliance on Department of Transportation regulations as evidence supporting Western Air Line's mandatory retirement policy because these regulations did not apply directly to flight engineers and were therefore irrelevant.