A divided U.S. Supreme Court rules that in age discrimination cases it is the plaintiff, not the defending employer, who must prove “by a preponderance of the evidence, that age was the ‘but-for’ cause of the challenged adverse employment action.”

The case involved the demotion of a 54-year-old employee whose former job duties were assigned to a younger employee. The older employee sued his employer, alleging that his reassignment violated the Age Discrimination in Employment Act, which makes it unlawful for an employer to take adverse action against an employee “because of such individual’s age.” The lower courts ruled on the suit based on precedents under Title VII discrimination cases for “mixed motive”--where an employee alleges that he suffered an adverse employment action because of both permissible and impermissible considerations. The Supreme Court now rules 5-4 that the burden shifting framework established under Title VII mixed motive claims does not apply to ADEA cases.

“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,” the Court majority says. “Unlike Title VII, which has been amended to explicitly authorize discrimination claims where an improper consideration was ‘a motivating factor’ for the adverse action [citation omitted] the ADEA does not provide that a plaintiff may establish discrimination by showing that age was simply a motivating factor.” Gross v. FBL Financial Service, Inc.