(a) Issuance of subpoena. (1) When the Secretary is authorized by statute to issue a subpoena in connection with an investigation being conducted by the Department, the attendance of a witness and the production of evidence relating to the investigation may be required by subpoena at any designated place, including the witness' place of business. Upon request of any representative of the Secretary involved in connection with the investigation, the subpoena may be issued by the Secretary, the Inspector General, or any Department official authorized pursuant to part 2 of this title to administer the program to which the subpoena relates, if the official who is to issue the subpoena is satisfied as to the reasonableness of the grounds, necessity, and scope of the subpoena. Except as provided in paragraph (a)(2) of this section, the authority to issue subpoenas may not be delegated or redelegated by the head of an agency.

(2) The Administrator, Grain Inspection, Packers and Stockyards Administration, may delegate the authority to issue subpoenas in connection with investigations being conducted under the Packers and Stockyards Act (7 U.S.C. 181-229), to the Deputy Administrator, Packers and Stockyards Programs.

(3) In the case of a subpoena issued under the Animal Health Protection Act (7 U.S.C. 8301-8317), Plant Protection Act (7 U.S.C. 7701-7772), or Title V of the Agricultural Risk Protection Act of 2000 (7 U.S.C. 2279e-2279f), the subpoena will be reviewed for legal sufficiency by the Office of the General Counsel, USDA.

(b) Service of subpoena. (1) A subpoena issued pursuant to this section may be served by:

(i) A U.S. Marshal or Deputy Marshal,

(ii) Any other person who is not less than 18 years of age, or

(iii) Certified or registered mailing of a copy of the subpoena addressed to the person to be served at his, her, or its last known residence or principal place of business or residence.

(2) Proof of service may be made by the return of service on the subpoena by the U.S. Marshal, or Deputy Marshal; or, if served by an individual other than a U.S. Marshal or Deputy Marshal, by an affidavit or certification of such person stating that he or she personally served a copy of the subpoena upon the person named in the subpoena; or, if service was by certified or registered mail, by the signed Postal Service receipt.

(3) In making personal service, the person making service shall leave a copy of the subpoena with the person subpoenaed; and the original, bearing or accompanied by the required proof of service, shall be returned to the official who issued the subpoena.