Code of Federal Regulations Title 7. Agriculture § 7.1.149 Subpoenas. 3]

(a) Issuance of subpoenas. The attendance and testimony of witnesses and the production of documentary evidence from any place in the United States on behalf of any party to the proceeding may be required by subpoena at any designated place of hearing if authorized by the statute under which the proceeding is conducted. Subpoenas shall be issued by the Judge upon a reasonable showing by the applicant of the grounds and necessity thereof;  and with respect to subpoenas for the production of documents, the request shall also show their competency, relevancy, and materiality. All requests for subpoenas shall be in writing, unless waived by the Judge for good cause shown. Except for good cause shown, requests for subpoenas shall be received by the Judge at least 10 days prior to the date set for the hearing.

(b) Service of subpoenas. Subpoenas may be served by any person not less than 18 years of age. The party at whose instance a subpoena is issued shall be responsible for service thereof. Subpoenas shall be served as provided in § 1.147.