Robert Barnett, a non-union employee of US Airways, Inc., was transferred to a less demanding mail room position after injuring his back while working in a cargo-handling job. When the position he held became open for bidding on the basis of seniority rules unilaterally adopted by the company, US Airways rejected Barnett's request to exempt his position from bidding, and he lost his job to another, more senior employee.

Claiming that US Airways had failed to reasonably accommodate his disability, Barnett filed suit under the Americans with Disabilities Act. The U.S. Court of Appeals for the Ninth Circuit reversed a lower court's dismissal of his action and ruled that "a seniority system is not a per se bar to reassigmnent" but should be considered as a factor in deciding whether a proposed accommodation would pose an undue hardship to the employer.

The U.S. Supreme Court reversed the Ninth Circuit's decision. In a 5-4 decision, the Court held that in situations involving a conflict between a requested accommodation and a seniority system, "the seniority system will prevail in the run of cases." However, the disabled employee "remains free to show that special circumstances warrant...that...the requested 'accommodation' is 'reasonable' on the particular facts," since "special circumstances might alter the important expectations" raised by a seniority system.

Impact: Employers may continue to award job assignments on the basis of union and employer non-union seniority systems, with only special circumstances altering their priority when considering a reasonable accommodation for a disabled employee.