California Code, Government Code - GOV § 19257

Any person acting in good faith in accepting an appointment or employment contrary to this part or the rules prescribed hereunder, shall be paid by the appointing power the compensation promised by or on behalf of the appointing power or, in case no compensation is so promised, then, the actual value of any service rendered and the expense incurred in good faith under such attempted appointment or employment, and has a cause of action against the appointing power therefor.