California Code, Government Code - GOV § 68082

Except as otherwise provided by law, during the officer's continuance in office, a court commissioner, judge, or court executive or administrative officer shall not practice law in any court of this state or act as attorney, agent, or solicitor in the prosecution of any claim or application for lands, pensions, patent rights, or other proceedings before any department of the state or general government or courts of the United States.  As used in this section, the practice of law includes being in partnership or sharing fees, commissions, or expenses in the practice of law with any person acting as an attorney in this state.