The Age Discrimination in Employment Act of 1967 (ADEA) makes it unlawful for an employer to take adverse action against an employee “because of such individual’s age.”  29 U.S.C. § 623(a). In a 5-4 decision issued today, the Supreme Court held that the ADEA does not authorize so-called mixed-motives claims and that an ADEA plaintiff therefore bears the burden of proving, by a preponderance of the evidence, that age was the “but for” cause of the challenged adverse employment action.

Writing for the majority, Justice Thomas rejected the suggestion that the ADEA should be interpreted in the same manner as Title VII of the Civil Rights Act of 1964.  In Price Waterhouse v. Hopkins, 490 U.S. 228 (1989), a plurality of the Court held that Title VII allows mixed-motives claims, i.e., claims alleging that an adverse employment decision was based on both permissible and impermissible considerations. Under Price Waterhouse, if a Title VII plaintiff shows that an impermissible consideration was a “motivating factor” for the adverse action, the burden of proof shifts to the defendant, who, to escape liability, must then show that the same action would have been taken regardless of the impermissible consideration. According to today’s majority opinion in Gross, that framework is inapplicable to claims brought under the ADEA: Although Congress amended Title VII to codify the plurality’s holding in Price Waterhouse, it did not make similar amendments to the ADEA. Slip op. 5–6. Moreover, in contrast to the amended Title VII, which expressly authorizes claims when an impermissible consideration was a “motivating factor,” the ADEA, which is silent as to burden of proof, imposes liability only when an adverse action was taken “because of” age. Therefore, the Court held, an ADEA plaintiff must prove that age was the “but for” cause of the employer’s adverse decision. Slip op. 7–9. Finally, the majority observed, even if the burden-shifting established by Price Waterhouse were doctrinally applicable to ADEA cases, it has proven difficult to implement.

Justice Stevens wrote the principal dissent, which was joined by Justices Souter, Ginsburg, and Breyer. As an initial matter, according to the dissent, in holding that mixed-motives claims were unavailable under the ADEA, the Court improperly reached a question that had not been presented in the petition for certiorari and was not briefed by the parties or their amici. Moreover, even if the issue were properly before the Court, Price Waterhouse compelled the opposite result, in the dissent’s view. When that case was decided, Title VII, like the ADEA today, barred adverse employment actions taken “because of” certain impermissible considerations. According to the dissenting Justices, the phrase “because of” as used in the ADEA should be construed, as it was in Price Waterhouse, to encompass situations in which an impermissible consideration was a “motivating factor” in an adverse employment action.

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