Master The Supreme Court held that ADEA plaintiffs must prove age was the but-for cause of an adverse employment action; mixed-motive burden shifting does not apply. with this comprehensive case brief.
Gross v. FBL Financial Services, Inc. is a landmark Supreme Court decision that reshaped the causation standard for age discrimination claims under the Age Discrimination in Employment Act (ADEA). Rejecting the mixed-motive framework that had developed in Title VII cases, the Court held that ADEA plaintiffs must prove, by a preponderance of the evidence, that age was the but-for cause of the adverse employment action. This decision clarified that the burden of persuasion never shifts to the employer under the ADEA, even where there is evidence of multiple motives.
For law students and employment practitioners, Gross is foundational because it differentiates the ADEA's text and remedial scheme from Title VII's, particularly in light of Congress's 1991 amendments to Title VII introducing the "motivating factor" standard. Gross has significant implications for litigation strategy, jury instructions, and the evidentiary showings necessary to prevail on age discrimination claims in the private sector.
557 U.S. 167 (U.S. Supreme Court 2009)
Jack Gross had worked for FBL Financial Services, Inc. for many years and rose to a senior management position. In 2003, during a company reorganization, FBL reassigned Gross—then in his fifties—from his position as claims administration director to a newly created role with diminished supervisory responsibilities. Much of his former authority was transferred to a younger employee. Gross sued under the ADEA, alleging disparate-treatment age discrimination. At trial, over FBL's objection, the district court gave a mixed-motive jury instruction allowing the jury to find for Gross if age was a motivating factor in the decision, unless FBL proved it would have made the same decision regardless of age. The jury returned a verdict for Gross. The Eighth Circuit reversed and remanded for a new trial, concluding the mixed-motive instruction was improper because Gross had not presented "direct evidence" of age discrimination. The Supreme Court granted certiorari to resolve whether a plaintiff must present direct evidence of age discrimination to obtain a mixed-motive instruction in an ADEA case.
Does the ADEA authorize mixed-motive liability and burden shifting such that, upon a plaintiff's showing that age was a motivating factor, the burden of persuasion shifts to the employer to prove it would have made the same decision; or must an ADEA plaintiff always prove that age was the but-for cause of the adverse employment action?
Under the ADEA, 29 U.S.C. § 623(a)(1), a plaintiff alleging disparate treatment 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 never shifts to the employer to show it would have taken the same action regardless of age. The mixed-motive framework recognized in Price Waterhouse v. Hopkins for Title VII and codified for certain Title VII claims by the Civil Rights Act of 1991, 42 U.S.C. § 2000e-2(m), does not apply to ADEA claims.
A plaintiff bringing a disparate-treatment claim under the ADEA must prove that age was the but-for cause of the adverse employment action; the ADEA does not authorize mixed-motive burden shifting. The Court reversed the Eighth Circuit and remanded for further proceedings consistent with this standard.
The Court, per Justice Thomas, began with statutory text. The ADEA makes it unlawful for an employer to take adverse action against an individual "because of such individual's age," 29 U.S.C. § 623(a)(1). The phrase "because of" ordinarily requires but-for causation, meaning the adverse action would not have occurred absent the prohibited consideration. Congress, when it intends to adopt a more lenient causation standard, knows how to do so expressly. In the Civil Rights Act of 1991, Congress amended Title VII to allow liability where a protected characteristic is a "motivating factor," 42 U.S.C. § 2000e-2(m), and provided a limited affirmative defense and remedial scheme for same-decision cases. Congress made no parallel amendment to the ADEA. The negative inference drawn from Congress's choice—to specifically alter Title VII's causation standard but not the ADEA's—supports a but-for standard under the ADEA. The Court rejected reliance on Price Waterhouse v. Hopkins, a fractured decision recognizing a mixed-motive framework in Title VII cases prior to the 1991 amendments. Price Waterhouse construed a different statute and, in any event, Congress subsequently codified a mixed-motive regime for Title VII only. The Court thus declined to transplant Price Waterhouse's framework into the ADEA, emphasizing that textual differences and subsequent legislative action matter. Because the ADEA does not contain a "motivating factor" provision, and because the statute's text indicates but-for causation, a mixed-motive instruction is improper in ADEA disparate-treatment cases. Finally, the Court clarified that the burden of persuasion remains with the plaintiff at all times under the ADEA. Even where a plaintiff presents evidence that age played some role, the plaintiff must still persuade the trier of fact that age was the determinative (but-for) cause of the adverse action. The Court therefore found the district court's mixed-motive instruction erroneous and remanded for proceedings consistent with the but-for causation standard. The Court did not resolve whether any form of "direct evidence" is required for ADEA claims, because the mixed-motive framework itself was inapplicable.
Gross is the seminal case establishing the but-for causation standard for private-sector ADEA disparate-treatment claims and rejecting mixed-motive burden shifting in that context. It realigns ADEA litigation around a stricter causation requirement than many Title VII status-based claims, affecting how plaintiffs frame their cases, the evidence they must marshal, and the jury instructions courts may give. For students, Gross is a critical example of textual interpretation, the limits of cross-statutory borrowing of doctrines, and how subsequent congressional amendments to one statute (Title VII) do not necessarily alter another (ADEA). Gross also became a platform for later decisions—most notably University of Texas Southwestern Medical Center v. Nassar (2013), which adopted a but-for causation standard for Title VII retaliation claims—and it informs the modern understanding of causation across employment discrimination law.
Under a but-for standard, the plaintiff must prove the adverse action would not have occurred absent the unlawful consideration—in ADEA cases, age must be the determinative cause. Under a motivating-factor standard, the plaintiff can prevail by showing the protected trait was one of multiple reasons for the decision, even if the employer would have taken the same action anyway (though remedies may be limited). Gross rejects the latter approach for ADEA disparate-treatment claims.
No. Gross addresses the ultimate burden of persuasion at trial and the causation standard, not the evidentiary order of proof at summary judgment. Courts continue to apply McDonnell Douglas to ADEA claims when analyzing circumstantial evidence, but after Gross the plaintiff still must ultimately prove age was the but-for cause of the adverse action.
Gross did not impose a direct-evidence requirement. The Court granted certiorari on whether direct evidence was required for a mixed-motive instruction, but it held that mixed-motive liability does not apply to the ADEA at all. Plaintiffs may rely on direct or circumstantial evidence, but they must convince the factfinder that age was the but-for cause.
Gross governs private-sector ADEA disparate-treatment claims. In Babb v. Wilkie (2020), the Supreme Court interpreted the federal-sector provision—requiring that personnel actions be "free from any discrimination based on age"—to permit liability without but-for causation for the decision itself, though but-for causation is still required for certain remedies. Thus, the standard for federal employees differs from the private sector post-Gross.
The 1991 Civil Rights Act added an explicit "motivating factor" provision to Title VII but did not amend the ADEA similarly. The Court drew a negative inference from this selective amendment: Congress knows how to authorize mixed-motive liability and chose not to do so for the ADEA. That textual and structural distinction was central to the Court's adoption of a but-for standard under the ADEA.
Gross v. FBL Financial Services definitively requires ADEA plaintiffs to prove that age was the but-for cause of an adverse employment action and rejects mixed-motive burden shifting for ADEA disparate-treatment claims. By grounding its analysis in statutory text and congressional amendments affecting only Title VII, the Court separated the ADEA's causation standard from the more lenient motivating-factor regime applicable to some Title VII claims.
For litigants, Gross changes how age discrimination cases are tried: plaintiffs must focus on establishing determinative causation, and courts must craft jury instructions accordingly. For law students, Gross is an essential study in statutory interpretation, the interaction between judicial doctrine and legislative amendment, and the practical impact of causation standards on civil rights enforcement.
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