Ds were charged with a conspiracy to destroy Government (P) property in violation of 18 U.S.C. 371. During pretrial proceedings, Ds moved to compel the United States to disclose certain electronic surveillance information and to conduct a hearing to determine whether this information 'tainted' the evidence on which the indictment was based or which the P intended to offer at trial. P filed an affidavit of the Attorney General, acknowledging that its agents had overheard conversations in which D had participated. The affidavit also stated that the Attorney General approved the wiretaps 'to gather intelligence information deemed necessary to protect the nation from attempts of domestic organizations to attack and subvert the existing structure of the Government.' The logs of the surveillance were filed in a sealed exhibit for in camera inspection by the District Court. The surveillance was conducted without prior judicial approval under the President's power to protect the national security. The District Court held that the surveillance violated the Fourth Amendment, and ordered P to make full disclosure to D of his overheard conversations. P filed a petition for a writ of mandamus to set aside the District Court order, which was stayed pending final disposition of the case. The Sixth Circuit held that the surveillance was unlawful and that the District Court had properly required disclosure of the overheard conversations. The Supreme Court granted certiorari.