From Consumer Wiki
Anyone who operates a limousine service must have a commercial driver's license issued by the California Department of Motor Vehicles and possess a permit to carry passengers issued by the California Public Utilities Commission (CPUC).
Department of Motor Vehicles
California Public Utilities Commission (CPUC)
For permit to carry passengers and household goods. The CPUC website has extensive information about requirements for licensing. Also to verify licensure or to file a complaint against a limousine service.
Consumers who wish to verify that limousine companies are licensed can check the database on the CPUC website at www.cpuc.ca.gov