California Code, Vehicle Code - VEH § 1656.5

(a) The Legislature finds that the department, by virtue of its interaction with millions of California drivers and vehicle owners each year, represents a valuable resource for the disbursement of important public safety and consumer information.

(b) The department may enter into a contract with a private vendor for the purpose of acquiring and utilizing message display systems. These systems may be used on the department's mailings or other property owned, leased, or controlled by the department. The information displayed shall be of appropriate benefit to the motoring public and the state's consumers, as determined by the department.

(c) A vendor under contract with the department may utilize a portion of the available time and space on the display systems that it provides for the purpose of advertising products or services. The advertising on a message display system shall not exceed 15 minutes in a 60-minute period. The extent of the access shall be established under the terms of the contract.

(d) The department shall determine whether a vendor's advertised product or service is consistent with and appropriate to the best interests of the motoring public. The department shall not enter into a contract with a vendor whose advertised product or service the department determines is not consistent with or appropriate to the best interests of the motoring public.