California Code, Public Utilities Code - PUC § 5374.5

(a) At the time of each bus terminal inspection conducted by the Department of the California Highway Patrol pursuant to subdivision (c) of Section 34501 of the Vehicle Code, every charter-party carrier of passengers shall furnish both the Department of the California Highway Patrol and the commission a list, prepared under oath, of all vehicles used in transportation for compensation during the period since the last inspection. The commission shall furnish a copy of the list to the carrier's insurer, if the carrier's accident liability protection is provided by a policy of insurance.This subdivision does not apply to a charter-party carrier of passengers engaged in the provision of a hired driver service when a rented motor vehicle is being operated by the hired driver.

(b) If the charter-party carrier's insurer informs the commission that the carrier has failed to obtain insurance coverage for any vehicle reported on the list, the commission may, in addition to any other penalty provided in this chapter, for a first occurrence, suspend the carrier's certificate or permit or impose a fine, or both, and for a second or subsequent occurrence may suspend or revoke the certificate or impose a fine, or both.