On June 18, 2009, the U.S. Supreme Court held in Gross v. FBL Financial Services, Inc. (No. 08- 441), that an employee bringing a disparate treatment claim under the Age Discrimination in Employment Act (ADEA) “must prove, by a preponderance of the evidence, that age was the ‘butfor’ cause of the challenged adverse employment action.”

Plaintiff Jack Gross, an employee at FBL Financial Group, sued his employer, alleging that it demoted him based on age when it reassigned him to a new position and transferred many of his job responsibilities to a younger employee who was formerly his subordinate. The District Court instructed the jury to return a verdict for Gross if he proved, by a preponderance of the evidence, that age was a motivating factor in FBL’s choice to demote him. The Eighth Circuit reversed, holding that the jury should not find for Gross unless he presented “direct evidence” that age was a motivating factor in his demotion.

In a 5-4 decision, the Supreme Court vacated and remanded. Although the question presented to the Court was “whether a plaintiff must present direct evidence of age discrimination in order to obtain a mixed-motives jury instruction [in an ADEA suit],” Justice Thomas, writing for the majority, found a threshold issue determinative: whether the ADEA authorizes a so-called mixed-motive discrimination claim in the first instance.

In Price Waterhouse v. Hopkins, the Court held that in a Title VII action the burden of persuasion shifts to the employer when the plaintiff shows that race or gender was a motivating factor in the employer’s adverse employment action. The employer then must prove that it would have taken the same adverse action even in the absence of a discriminatory motive. Many Courts of Appeals previously held that this burden-shifting framework also applied to discrimination claims brought under the ADEA.

The Court, however, rejected the analogy between ADEA and Title VII claims. The Court noted that although Congress codified the Price Waterhouse holding by amending Title VII, Congress did not make similar amendments to the ADEA. Moreover, the Court emphasized that it has never applied the Price Waterhouse burden-shifting framework to ADEA claims. Finally, the Court suggested that Price Waterhouse may have been improperly decided, and that applying Price Waterhouse’s rationale to ADEA claims could be problematic because its burden-shifting framework has created many practical difficulties for the courts.

The Court also examined the text of the ADEA, noting that the statute prohibits employers from taking certain actions “because of” age. Accordingly, because dictionaries define the words “because of” to mean “by reason of,” on account of,” or “as the cause of an event,” an ADEA disparate-treatment plaintiff must prove that an employer would not have taken adverse employment actions against the plaintiff “but-for” the plaintiff’s age.

Two justices wrote dissenting opinions. Justice Stevens, joined by three other justices, objected in part on the ground that both Title VII and the ADEA prohibit discrimination “because of” certain characteristics, and therefore the majority’s reading of the ADEA is inconsistent with the settled reading of the same language in Title VII. Moreover, Justice Stevens noted that all of the Courts of Appeals that have considered this issue have applied Price Waterhouse to ADEA claims. Justice Breyer, joined by two other justices, commented that proving “but-for” causation in a typical tort case involves reasonably concrete proof, but that this is a much more difficult task when proving motive in a discrimination case.

For the time being, the holding in Gross favors employers who face ADEA disparate-treatment claims as it essentially eliminates ADEA “mixed-motive” claims. However, some commentators suggest that Congress will move quickly to amend the ADEA to expressly permit these claims.