Specific Claims· 13 min read

Age Discrimination (ADEA): What You Need to Prove

Age discrimination claims under the ADEA are procedurally and substantively distinct from Title VII claims in ways that matter significantly in practice. The causation standard is stricter.

Age discrimination claims under the ADEA are procedurally and substantively distinct from Title VII claims in ways that matter significantly in practice. The causation standard is stricter. The damages available are different. The right-to-sue process works differently. And the Supreme Court has made ADEA claims harder to win in key respects. Workers pursuing age discrimination claims need to understand these differences — and the attorneys they hire need to understand them too.

The ADEA's Coverage

The Age Discrimination in Employment Act protects workers who are 40 or older from discrimination based on age. It covers hiring, firing, pay, job assignments, promotions, layoffs, training, and all other terms and conditions of employment. It applies to employers with 20 or more employees — a higher threshold than Title VII's 15 — which means some smaller employers covered by Title VII aren't covered by the ADEA.

The "But-For" Causation Standard

The most important distinction between ADEA and Title VII claims is causation. Under Title VII, a plaintiff need only show that a protected characteristic was a "motivating factor" in the adverse action — even if other factors also played a role. Under the ADEA, the Supreme Court held in Gross v. FBL Financial Services (2009) that age must be the "but-for" cause of the adverse action: the plaintiff must prove that the employer would not have taken the adverse action absent the discriminatory motivation. This stricter standard means that mixed-motive age cases — where the employer had both a legitimate reason and age-based animus — are harder to prove than equivalent Title VII cases. The employer's legitimate reason is not just a defense; it potentially defeats the claim.

What You Need to Prove

Under McDonnell Douglas, the ADEA prima facie case requires: (1) the plaintiff was at least 40; (2) qualified for the position; (3) suffered an adverse employment action; and (4) was treated less favorably than someone substantially younger. The "substantially younger" requirement has been interpreted to mean a meaningful age gap — courts have found prima facie cases where the replacement was in their 30s, but the more significant the age gap, the stronger the inference. Comparator evidence comparing treatment of workers under 40 (or substantially younger) to treatment of workers 40 and over is the most direct way to build an ADEA case. Comments about age from decision-makers — references to "energy," "fresh ideas," "digital natives," wanting someone who can "grow with the company" — can constitute direct or circumstantial evidence.

Damages Under the ADEA

The ADEA does not provide compensatory or punitive damages. It provides back pay and liquidated damages — liquidated damages equal to the back pay amount, available when the employer's violation was "willful" (meaning the employer knew or recklessly disregarded that its conduct violated the ADEA). There are no Title VII-style damages caps under the ADEA because the damages categories are fundamentally different. The right-to-sue process also differs: an ADEA plaintiff may file in federal court 60 days after filing the EEOC charge, without waiting for a right-to-sue letter.

Key Cases

*Gross v. FBL Financial Services* (2009) established but-for causation. *O'Connor v. Consolidated Coin Caterers Corp.* (1996) held that the ADEA plaintiff need not show replacement by someone outside the protected class entirely — only by someone substantially younger.

Key takeaways

The ADEA's Coverage
The "But-For" Causation Standard
What You Need to Prove
Damages Under the ADEA
Key Cases

Citations

Age Discrimination in Employment Act, 29 U.S.C. § 621 et seq — Cited authority
Gross v. FBL Financial Services, Inc., 557 U.S. 167 (2009) — Cited authority
O'Connor v. Consolidated Coin Caterers Corp., 517 U.S. 308 (1996) — Cited authority

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Pregnancy Discrimination: What You Need to Prove