In 1990, Robert Barnett (plaintiff) sustained a back injury while working as a cargo handler for US Airways, Inc. (US Air) (defendant). Barnett used seniority rights to transfer to a less strenuous mailroom position. US Air had a seniority system under which various job positions periodically opened up to seniority-based employee bidding. In 1992, Barnett learned other employees with higher seniority planned to bid for his mailroom position. Barnett asked US Air to accommodate his physical disability by making an exception to its seniority system and allowing him to keep the mailroom job. US Air decided not to grant the request. Barnett lost his mailroom job. Barnett sued US Air under the Americans with Disabilities Act (ADA), 42 U.S.C. § 12101 et seq., alleging unlawful disability discrimination. Barnett argued the requested accommodation—permanent assignment to the mailroom—was reasonable under the ADA. The district court granted summary judgment to US Air, but the court of appeals reversed. US Air sought review by the United States Supreme Court.