Olson (plaintiff), a mine worker, and another mine worker (and spouse) brought suit against the United States (defendant) claiming that the negligence of a federal mine inspector contributed to a severe mine accident in which the mine workers suffered injuries. The federal district court dismissed the lawsuit upon finding that Arizona law would not necessarily find a private person liable in tort given the same facts. Olson appealed, and the Ninth Circuit Court of Appeals reversed. The reversal was based on the court’s holding that where “unique governmental functions” are at issue, the Federal Tort Claims Act (FTCA) waives sovereign immunity for the federal government if “a state or municipal entity would be [subject to liability] under the law…where the activity occurred.” The court held federal mine inspections to be one such “unique governmental function” because it has no private sector equivalent. Finally, the court held the United States liable in tort because Arizona law would make “state or municipal entities” liable under the circumstances. The United States Supreme Court considered the case.