California Code, Vehicle Code - VEH § 14104.5

(a) Before a hearing has commenced, the department, or the hearing officer or hearing board, shall issue subpoenas or subpoenas duces tecum, or both, at the request of any party, for attendance or production of documents at the hearing.  After the hearing has commenced, the department, if it is hearing the case, or the hearing officer sitting alone, or the hearing board, may issue subpoenas or subpoenas duces tecum, or both.

(b) Notwithstanding Section 11450.20 of the Government Code, subpoenas and subpoenas duces tecum issued in conjunction with the hearings may be served by first-class mail.