Employees have three traditional methods to prove intentional discrimination: (1) direct evidence (comments that evidence a discriminatory animus made by a decision-maker in close temporal proximity to the challenged employment decision); (2) indirect evidence (which uses the McDonnell Douglas burden-shifting formula); and (3) a mixed-motive (discrimination was a motivating or a substantial factor in the employer’s action, and the employer cannot show that it would have taken the same action regardless of that impermissible consideration).
This morning, in Gross v. FBL Financial Services, Inc. [PDF], the Supreme Court held that there is no such thing as a mixed-motive in age discrimination cases under the ADEA. To succeed on an disparate treatment claim under the ADEA, a plaintiff must now prove that age was the “but-for” (that is, the only) cause of the challenged adverse employment action:
We hold that a plaintiff bringing a disparate-treatment claim pursuant to the ADEA must prove, by a preponderance of the evidence, that age was the “but-for” cause of the challenged adverse employment action. The burden of persuasion does not shift to the employer to show that it would have taken the action regardless of age, even when a plaintiff has produced some evidence that age was one motivating factor in that decision.Because age discrimination plaintiffs must now prove “but for” causation, it is more important than ever for employers to meticulously document employees’ performance problems and other disciplinary action. A well-documented personnel file will make it that much more difficult for a plaintiff to prove that age was the sole reason motivating the termination or other action.