In Department of Homeland Security vs. Robert J. MacLean, the U.S. Supreme Court found that a federal air marshal’s disclosure of air security plans was protected under the Federal Whistleblower Protection Act and was not prohibited by law. In a 7-2 decision, written by Chief Justice John Roberts, the Court upheld a lower court’s decision and affirmed a rare victory for federal whistleblowers who expose legal violations or health and safety risks within their profession.

The Federal Whistleblower Protection Act protects employees from retaliation for reporting violations of law, rules or regulations, gross mismanagement, gross waste of funds, an abuse of authority, or a substantial and specific danger to public health or safety. However, the Act disallows disclosures “specifically prohibited by law” or by executive order classifying the information as secret.

In this case, Robert MacLean was an undercover, armed air marshal whose primary duty was to help thwart terrorist activity. In 2003, the Department of Homeland Security issued a confidential warning that al-Qaida planned to hijack a U.S. flight, so air marshals were gathered for secret briefings.

However, 48 hours later, the Transportation Security Administration reduced overnight flights for air marshals. This dumbfounded MacLean, so, fearing for the public’s safety, he elected to leak the news to MSNBC.

The leak’s source was not discovered until three years later, at which point Maclean was fired for disclosing sensitive security information. Eventually, a federal court of appeals found that although Maclean’s disclosure violated TSA’s regulation, it did not violate federal law and, therefore, was protected.

The government appealed, arguing that such disclosures would “‘gravely endanger public safety’ by making the confidentiality of sensitive security information depend on the idiosyncratic judgment of each of the TSA's 60,000 employees.” However, the Court concluded that the Act only disallowed disclosures “specifically prohibited by law” and, had Congress intended to include disclosures violating agency rules or regulations, it would have drafted the language to say so. Therefore, the government’s concerns would have to be addressed by Congress or the president, not by the Court.