California Code, Public Contract Code - PCC § 10410

No officer or employee in the state civil service or other appointed state official shall engage in any employment, activity, or enterprise from which the officer or employee receives compensation or in which the officer or employee has a financial interest and which is sponsored or funded, or sponsored and funded, by any state agency or department through or by a state contract unless the employment, activity, or enterprise is required as a condition of the officer's or employee's regular state employment.  No officer or employee in the state civil service shall contract on his or her own individual behalf as an independent contractor with any state agency to provide services or goods.