Cal. Gov. Code § 11191

Each witness, other than an officer or employee of the State or of a political subdivision of the State, who appears by order of the head of a department shall receive for his attendance the same fees and all witnesses shall receive the same mileage allowed by law to a witness in civil cases. The amounts shall be paid by the party at whose request the witness is subpenaed. The mileage, and fees, if any, of a witness subpenaed by the head of a department, but not at the request of a party, shall be paid from the funds appropriated for the use of the department in the same manner as other expenses of the department are paid.