Cal. Public Utilities Code § 728.5

(a) The commission may establish rates or charges for the transportation of passengers and freight by railroads and other transportation companies, except motor carriers of property, and no railroad or other transportation company under its jurisdiction, except motor carriers of property, shall charge or demand or collect or receive a greater or less or different compensation for that transportation of passengers or freight, or for any service in connection therewith, between the points named in any tariff of rates established by the commission than the rates, fares and charges which are specified in that tariff. The commission may examine books, records and papers of all railroad and other transportation companies, except motor carriers of property; may hear and determine complaints against railroad and other transportation companies; and may issue subpoenas and all necessary process and send for persons and papers. The commission and each of the commissioners may administer oaths, take testimony and punish for contempt in the same manner and to the same extent as courts of record. The commission may prescribe a uniform system of accounts to be kept by all railroad and other transportation companies, except motor carriers of property. (b) Subdivision (a) is not applicable to network railroad transportation.