For the purposes of carrying out its functions and duties in connection with any investigation authorized by law, the commission or its duly authorized agent or agents (1) shall have access to and the right to copy any document, paper, or record, pertinent to the subject matter under investigation, in the possession of any person, firm, copartnership, corporation, or association engaged in the production, importation, or distribution of any article under investigation, (2) may summon witnesses, take testimony, and administer oaths, (3) may require any person, firm, copartnership, corporation, or association to produce books or papers relating to any matter pertaining to such investigation, and (4) may require any person, firm, copartnership, corporation, or association, to furnish in writing, in such detail and in such form as the commission may prescribe, information in their possession pertaining to such investigation. Any member of the commission may sign subpenas, and members and agents of the commission, when authorized by the commission, may administer oaths and affirmations, examine witnesses, take testimony, and receive evidence.

Such attendance of witnesses and the production of such documentary evidence may be required from any place in the United States at any designated place of hearing. And in case of disobedience to a subpena the commission may invoke the aid of any district or territorial court of the United States in requiring the attendance and testimony of witnesses and the production of documentary evidence, and such court within the jurisdiction of which such inquiry is carried on may, in case of contumacy or refusal to obey a subpena issued to any corporation or other person, issue an order requiring such corporation or other person to appear before the commission, or to produce documentary evidence if so ordered or to give evidence touching the matter in question; and any failure to obey such order of the court may be punished by such court as a contempt thereof.

At the request of the commission, any such court shall have jurisdiction to issue writs of mandamus commanding compliance with the provisions of this part or any order of the commission made in pursuance thereof.

The commission may order testimony to be taken by deposition in any proceeding or investigation pending before the commission at any stage of such proceeding or investigation. Such depositions may be taken before any person designated by the commission and having power to administer oaths. Such testimony shall be reduced to writing by the person taking the deposition, or under his direction, and shall then be subscribed by the deponent. Any person, firm, copartnership, corporation, or association, may be compelled to appear and depose and to produce documentary evidence in the same manner as witnesses may be compelled to appear and testify and produce documentary evidence before the commission, as hereinbefore provided.

Witnesses summoned before the commission shall be paid the same fees and mileage that are paid witnesses in the courts of the United States, and witnesses whose depositions are taken and the persons taking the same, except employees of the commission, shall severally be entitled to the same fees and mileage as are paid for like services in the courts of the United States.

The commission is authorized, in order to ascertain any facts required by subdivision (d) of section 1332 of this title to require any importer and any American grower, producer, manufacturer, or seller to file with the commission a statement, under oath, giving his selling prices in the United States of any article imported, grown, produced, fabricated, manipulated, or manufactured by him.

The Commission shall be represented in all judicial proceedings by attorneys who are employees of the Commission or, at the request of the Commission, by the Attorney General of the United States.

Any correspondence, private letters of reprimand, and other documents and files relating to violations or possible violations of administrative protective orders issued by the Commission in connection with investigations or other proceedings under this subtitle shall be treated as information described in section 552(b)(3) of title 5.