The outcome could serve as a judicial warm-up for a separate high-profile challenge to a more controversial Arizona immigration reform law working its way through lower courts. That statute would, among other things, give local police a greater role in arresting suspected illegal immigrants.

The hiring case turned on whether state law tramples on federal authority.

“Arizona has taken the route least likely to cause tension with federal law,” wrote Chief Justice John Roberts. “It relies solely on the federal government’s own determination of who is an unauthorized alien, and it requires Arizona employers to use the federal government’s own system for checking employee status.”