Cal. Elec. Code § 18542

Every employer, whether a corporation or natural person, or any other person who employs, is guilty of a misdemeanor if, in paying his or her employees the salary or wages due them, encloses their pay in pay envelopes upon which or in which there is written or printed the name of any candidate or any political mottoes, devices, or arguments containing threats, express or implied, intended or calculated to influence the political opinions or actions of the employees.