subsistence, and other necessary expenses incurred by them in the performance of their duties to the extent authorized by chapter 57 of title 5, United States Code. 5. Powers of the Commission (a) Hearings and sessions The Commission may, for the purpose of carrying out the provisions of this Act, hold such hearings and sit and act at such times and at such places in the United States, and request the attendance and testimony of such witnesses and the production of such books, records, correspondence, memoranda, papers, and documents, as the Commission considers appropriate. The Commission may invoke the aid of an appropriate United States district court to require, by subpoena or otherwise, such attendance, testimony, or production. (b) Powers of subcommittees and members Any subcommittee or member of the Commission may, if authorized by the Commission, take any action which the Commission is authorized to take by this section. (c) Obtaining official data The Commission may acquire directly from the head of any department, agency, or instrumentality of the executive branch of the Government, available information which the Commission considers useful in the discharge of its duties. All departments, agencies, and instrumentalities of the executive branch of the Government shall cooperate with the Commission with respect to such information and shall furnish all information requested by the Commission to the extent permitted by law. 6. Administrative provisions (a) Staff The Commission may, without regard to section 5311(b) of title 5, United States Code, appoint and fix the compensation of such personnel as the Commission considers appropriate. (b) Applicability of certain civil service laws The staff of the Commission may be appointed without regard to the provisions of title 5, United States Code, governing appointments in the competitive service, and without regard to the provisions of chapter 51 and subchapter III of chapter 53 of such title relating to classification and General Schedule pay rates, except