Michael Santoro suffered a work-related injury and later died of nerve cancer. Santoro’s widow (plaintiff) filed a claim for benefits against his former employer (defendant) under the Longshore and Harbor Workers’ Compensation Act. The administrative law judge relied on the Department of Labor’s true doubt rule in finding Santoro’s widow was entitled to benefits. The true doubt rule placed the burden of persuasion on the party opposing the benefits claim. The Department’s Benefits Review Board affirmed. The Court of Appeals vacated the Board’s decision, finding that the true doubt rule conflicted with § 7(c) of the Administrative Procedure Act (APA), which placed the burden of persuasion on the claimant. The United States Supreme Court granted certiorari.