California Code, Public Utilities Code - PUC § 5360

Subject to the exclusions of Section 5353, “charter-party carrier of passengers” means every person engaged in the transportation of persons by motor vehicle for compensation, whether in common or contract carriage, over any public highway in this state.  “Charter-party carrier of passengers” includes any person, corporation, or other entity engaged in the provision of a hired driver service when a rented motor vehicle is being operated by a hired driver.