Employers arguing in ADEA disparate impact cases that their employment decisions were based on "reasonable factors other than age" bear the burden of persuasion, ruled the U.S. Supreme Court on June 19. Meacham v. Knolls Atomic Power Lab., No. 06-1505 (June 19, 2008) (PDF).
The RFOA defense provides that "[i]t shall not be unlawful for an employer … to take any action otherwise prohibited under [the ADEA's operative anti-discrimination subsections] where the differentiation is based on reasonable factors other than age." 29 U.S.C. § 623(f)(1).
The upshot of this ruling for employers is that defending ADEA disparate impact claims will be a little more difficult. If the plaintiff can show a particular employment practice disproportionately hurt older workers, the onus will be on the employer to prove (not just articulate) the reasonableness of a non-age related factor. Disparate impact cases are rare, and this decision will not likely cause problems for too many employers.