California Code, Financial Code - FIN § 17422

A joint control agent, unless acting pursuant to written instructions of his principals, shall not disburse funds for the payment of the cost of labor, materials, services, permits, fees, or other items of expense incurred in the construction of improvements upon real property until such time as he determines that the person furnishing such labor, materials, services, permits, fees, or other items has substantially complied with the specifications contained in the control agreement.