[JURIST] The US Supreme Court [official website] ruled [opinion, PDF] Wednesday in Department of Homeland Security v. MacLean [SCOTUSblog backgrounder] that unless a disclosure is specifically prohibited by law, the code of Prohibited Personnel Practices [text] can bar an agency from taking action against an employee who intentionally divulges sensitive security information. Shortly after the passage of the Aviation and Transportation Security Act [Cornell LII backgrounder] in November of 2001, the Transportation Security Administration (TSA) [official website] promulgated a regulation prohibiting the unauthorized disclosure of “sensitive security information,” including “[s]pecific details of aviation security measures … [such as] information concerning specific numbers of Federal Air Marshals, deployments or missions, and the methods involved in such operations.” The Supreme Court held that the exception for disclosures specifically prohibited by law did not extend to regulations issued by agencies, or else agencies would be able to insulate themselves from whistleblowing.

The question arose when a former federal air marshal revealed TSA plans to the media in an effort to create a controversy that would change the agency’s practices. The air marshal claimed that his subsequent removal was in violation of Prohibited Personnel Practices. The Supreme Court heard oral arguments [JURIST report] on the matter in November. Certiorari was granted [JURIST report] in May.