(a) Subpoenas. Except as provided in paragraph (c) of this section, subpoenas requiring the attendance of witnesses, or the production of documentary or tangible evidence, for the purpose of taking depositions or at a hearing, may be issued by the presiding law judge (or the chief law judge, if the proceeding has not been assigned to a law judge) upon application by any party. The application shall show the general relevance and reasonable scope of the evidence sought. Any person upon whom a subpoena is served may, within 7 days after service of the subpoena, but in any event prior to the return date thereof, file with the law judge who issued the subpoena a motion to quash or modify the subpoena, and such filing shall stay the effectiveness of the subpoena pending final action by the law judge on the motion.

(b) Witness fees. Witnesses shall be entitled to the same fees and expenses for mileage as are paid to witnesses in the courts of the United States. The fees and expenses shall be paid by the party at whose request the witness is subpoenaed or appears. The Board may decline to process a proceeding further should a party fail to compensate a witness pursuant to this paragraph.

(c) Board Members, officers and employees. In order to encourage a free flow of information to the Board's accident investigators, the Board disfavors the use of its personnel in enforcement proceedings. Therefore, the provisions of paragraph (a) of this section are not applicable to Board Members, officers and employees, or the production of documents in their custody. Applications for subpoenas requiring the attendance of such persons, or the production of such documents, must be addressed to the General Counsel, and shall set forth the need of the moving party for the testimony or documents sought, and a showing that such material is not now, and was not otherwise, reasonably available from other sources. Only upon the General Counsel's written approval for the issuance of a subpoena requiring a Board Member, officer or employee to provide testimony and/or to produce documents in connection with discovery or at a hearing may a law judge issue such a subpoena. The law judge shall not permit the testimony or documentary evidence provided by a Board Member, officer or employee to include any expression of opinion, or any account of statements of a party made during the Board's investigation of any accident.