California Code, Government Code - GOV § 8288

(a) No employee of the commission and no member appointed by the Governor shall, with respect to any proposed legislation concerning matters assigned to the commission for study pursuant to Section 8293, advocate the passage or defeat of the legislation by the Legislature or the approval or veto of the legislation by the Governor. An employee or member of the commission appointed by the Governor shall not advocate the passage or defeat of any legislation or the approval or veto of any legislation by the Governor, in that person's official capacity as an employee or member.

(b) An employee or member of the commission may appear and testify at any legislative committee hearing on legislation to implement a commission recommendation, for the purpose of explaining the recommendation and answering questions posed by the legislative committee members, if the employee or member of the commission does not violate the restrictions described in subdivision (a).