The Freedom of Information Act exempts from its mandate certain specified categories of information, including matters that are 'specifically required by Executive order to be kept secret in the interest of the national defense or foreign policy,' § 552 (b)(1), or are 'inter-agency or intra-agency memorandums or letters which would not be available by law to a party other than an agency in litigation with the agency,' § 552 (b)(5). An article that appeared in a Washington, D. C., newspaper indicating that the President had received conflicting recommendations on the advisability of the underground nuclear test scheduled for that coming fall. Mink (Ps), Members of Congress, brought suit under the Freedom of Information Act of 1966 to compel disclosure of nine documents that various officials had prepared for the President concerning a scheduled underground nuclear test. All but three were classified as Top Secret or Secret under E. O. 10501, and EPA (D) represented that all were inter-agency or intra-agency documents used in the Executive Branch's decisionmaking processes. D moved for summary judgment on the ground that the materials were specifically exempted from disclosure under subsections (b)(1) and (b)(5) of the Act. D filed an affidavit of John N. Irwin II, the Under Secretary of State to support its position. The District Court granted summary judgment on the ground that each of the nine documents sought was exempted from compelled disclosure by §§ (b)(1) and (b)(5) of the Act. The Court of Appeals reversed, concluding that subsection (b)(1) of the Act permits the withholding of only the secret portions of those documents bearing a separate classification under Executive Order 10501: 'If the non-secret components [of such documents] are separable from the secret remainder and may be read separately without distortion of meaning, they too should be disclosed.' The District Judge was ordered to examine the classified documents 'looking toward their possible separation for purposes of disclosure or nondisclosure.' The Court of Appeals concluded that all nine contested documents fell within subsection (b)(5) of the Act, but construed that exemption as shielding only the 'decisional processes' reflected in internal Government memoranda, not 'factual information' unless that information is 'inextricably intertwined with policymaking processes.' The court ordered in camera inspection to determine factual data that could be separated. The Supreme Court granted certiorari.