In a case challenging the requirement of showing a government-issued photo ID to fly on a domestic airline, the U.S. justice department filed a motion with the 9th Circuit Court of Appeals to allow the government to file its brief and record under seal and in camera. The Court denied the motion.
According to this AP report, the U.S. contends that the reasons for and requirements of any federal directive dealing with transportation must be kept secret for national security reasons. The government has even refused to confirm or deny the existence of a directive requiring airlines to check ID.
The government also requested that oral arguments be closed to the public. Julie Hilden discusses the issues involved in the motion and argues for a more moderate solution in Should The Government's Request to Close Court Proceedings Relating to Airline Anti-Terror List Criteria Be Granted?