28 CFR § 2.104 - Issuance of subpoena for appearance of witnesses or production of documents.
(a)
(1) If any adverse witness (i.e., a person who has given information upon which revocation may be based) refuses, upon request by the Commission, to appear at a probable cause hearing or local revocation hearing, a Commissioner may issue a subpoena for the appearance of such witness. Such subpoena may also be issued at the discretion of a Commissioner in the event such adverse witness is judged unlikely to appear as requested.
(2) In addition, a Commissioner may, upon a showing by the parolee that a witness whose testimony is necessary to the proper disposition of his case will not appear voluntarily at a local revocation hearing or provide an adequate written statement of his testimony, issue a subpoena for the appearance of such witness at the revocation hearing.
(3) Such subpoenas may also be issued at the discretion of a Commissioner if deemed necessary for the orderly processing of the case.
(b) A subpoena issued pursuant to paragraph (a) of this section may require the production of documents as well as, or in lieu of, a personal appearance. The subpoena shall specify the time and the place at which the person named therein is commanded to appear, and shall specify any documents required to be produced.
(c) A subpoena may be served by any Federal or District of Columbia officer authorized to serve criminal process. The subpoena may be served at any place within the judicial district in which the place specified in the subpoena is located, or any place where the witness may be found. Service of a subpoena upon a person named therein shall be made by delivering a copy thereof to such a person.
(d) If a person refuses to obey such subpoena, the Commission may petition a court of the United States for the judicial district on which the parole proceeding is being conducted, or in which such person may be found, to require such person to appear, testify, or produce evidence. If the court issues an order requiring such person to appear before the Commission, failure to obey such an order is punishable as contempt. 18 U.S.C. 4214 (1976).