Pursuant to the Federal Advisory Committee Act (FACA), 5 U.S.C. App. § 2, the Sierra Club and Judicial Watch (plaintiffs) sued the National Energy Policy Development Group (NEPDG), Vice President Dick Cheney who served as NEPDG’s chair, and a number of NEPDG’s participants, including federal officials, agencies, and private parties alleged to have taken part in the group’s deliberations (defendants). NEPDG had been established by the Office of the President for the purpose of advising the president on federal energy matters. The defendants moved to dismiss the plaintiffs’ suit. The district court dismissed the claims against the private defendants and NEPDG itself but allowed claims against Cheney and other officials to proceed. Based on the plaintiffs’ allegation that the private parties were “de facto members” of NEPDG, the court concluded that the defendants should not be immune from suit under a FACA exemption that applied to groups established by the president that were composed entirely of government officials or employees. Seeking to avoid discovery, Cheney and the other officials sought a writ of mandamus from the District of Columbia Court of Appeals. The court of appeals denied the writ on the ground that the defendants could defend against discovery by asserting executive privilege. The defendants petitioned the United States Supreme Court for certiorari.