California Code, Public Contract Code - PCC § 3300

(a) Any public entity, as defined in Section 1100, the University of California, and the California State University shall specify the classification of the contractor's license which a contractor shall possess at the time a contract is awarded.  The specification shall be included in any plans prepared for a public project and in any notice inviting bids required pursuant to this code.

This requirement shall apply only with respect to contractors who contract directly with the public entity.

(b) A contractor who is not awarded a public contract because of the failure of an entity, as defined in subdivision (a), to comply with that subdivision shall not receive damages for the loss of the contract.