8 CFR § 1287.4 - Subpoena.
(a) Who may issue - (1) Criminal or civil investigations. For provisions relating to the authority of immigration officers to issue a subpoena requiring the production of records and evidence for use in criminal or civil investigations, see 8 CFR 287.4(a)(1).
(2) Proceedings other than naturalization proceedings - (i) Prior to commencement of proceedings. For provisions relating to who may issue a subpoena requiring the attendance of witnesses or the production of documentary evidence, or both, for use in any proceeding under this title, other than under 8 CFR part 335, or any application made ancillary to the proceeding, see 8 CFR 287.4(a)(2)(i).
(ii) Subsequent to commencement of any proceeding.
(A) In any proceeding under this chapter and in any proceeding ancillary thereto, an immigration judge having jurisdiction over the matter may, upon his/her own volition or upon application of government counsel, the alien, or other party affected, issue subpoenas requiring the attendance of witnesses or for the production of books, papers and other documentary evidence, or both.
(B) Application for subpoena. A party applying for a subpoena shall be required, as a condition precedent to its issuance, to state in writing or at the proceeding, what he/she expects to prove by such witnesses or documentary evidence, and to show affirmatively that he/she has made diligent effort, without success, to produce the same.
(C) Issuance of subpoena. Upon being satisfied that a witness will not appear and testify or produce documentary evidence and that the witness' evidence is essential, the immigration judge shall issue a subpoena.
(D) Appearance of witness. If the witness is at a distance of more than 100 miles from the place of the proceeding, the subpoena shall provide for the witnesses' appearance at the Service office nearest to the witness to respond to oral or written interrogatories, unless the Service indicates that there is no objection to bringing the witness the distance required to enable him/her to testify in person.
(b) Form of subpoena. All subpoenas shall be issued on Form I-138.
(1) Criminal or civil investigations. The subpoena shall command the person or entity to which it is addressed to attend and to give testimony at a time or place specified. A subpoena shall also command the person or entity to which it is addressed to produce the books, papers, or documents specified in the subpoena. A subpoena may direct the taking of a deposition before an officer of the Service.
(2) Proceedings other than naturalization proceedings. Every subpoena issued under the provisions of this section shall state the title of the proceeding and shall command the person to whom it is directed to attend and to give testimony at a time and place specified. A subpoena shall also command the person to whom it is directed to produce the books, papers, or documents specified in the subpoena. A subpoena may direct the making of a deposition before an officer of the Service.
(c) Service. For provisions relating to who may serve a subpoena issued under this section, see 8 CFR 287.4(c).
(d) Invoking aid of court. If a witness neglects or refuses to appear and testify as directed by the subpoena served upon him or her in accordance with the provisions of this section, the immigration judge issuing the subpoena shall request the United States Attorney for the district in which the subpoena was issued to report such neglect or refusal to the United States District Court and to request such court to issue an order requiring the witness to appear and testify and to produce the books, papers, or documents designated in the subpoena.