49 CFR § 1113.2 - Subpoenas.
(a) Issuance. A subpoena may be issued upon the direction of the Board on its own motion or upon request. A subpoena may be issued by the Board or by the officer presiding at a hearing and must be signed by the Director of the Office of Proceedings or a member of the Board.
(1) A request for a subpoena to compel the appearance of a person at a hearing to give oral testimony, but not to produce documents, may be made either by letter (only the original need be filed with the Board) or orally upon the record at the hearing. A showing of general relevance and reasonable scope of the evidence sought to be introduced through the subpoenaed person may be required.
(2) A request for a subpoena to compel a witness to produce documentary evidence should be made in writing by petition. The petition should specify with particularity the books, papers, or documents desired and facts expected to be proved, and should show the general relevance and reasonable scope of the evidence sought. The officer presiding at a hearing may grant a request for such a subpoena made orally upon the record.
(c) Service. The original subpoena should be exhibited to the person served, should be read to him if he is unable to read, and a copy should be delivered to him by the officer or person making service.
(d) Return. If service of subpoena is made by a United States marshal or his deputy, service should be evidenced by his return of the subpoena. If made by any other person, such person shall make an affidavit stating the date, time and manner of service; and return such affidavit on, or with, the original subpoena in accordance with the form thereon. In case of failure to make service the reasons for the failure should be stated on the original subpoena. The written acceptance of service of a subpoena by the person subpoenaed will be sufficient without other evidence of return. The original subpoena bearing or accompanied by the required return, affidavit, statement, or acceptance of service, should be returned forthwith to the Chief, Section of Administration, Office of Proceedings, unless otherwise directed.
(e) Witness fees. A witness who is summoned and responds to the summons is entitled to the same fee as is paid for like service in the courts of the United States. Such fee is to be paid by the party at whose insistence the testimony is taken at the time the subpoena is served, except that when the subpoena is issued on behalf of the United States or an officer or agency thereof, fees and mileage need not be tendered at the time of service.