California Code, Civil Code - CIV § 1947.11

(a) In any city, county, or city and county which administers a system of controls on the price at which residential rental units may be offered for rent or lease and which requires the registration of rents, upon the establishment of a certified rent level, any owner who charges rent to a tenant in excess of the certified lawful rent ceiling shall refund the excess rent to the tenant upon demand. If the owner refuses to refund the excess rent and if a court determines that the owner willfully or intentionally charged the tenant rent in excess of the certified lawful rent ceiling, the court shall award the tenant a judgment for the excess amount of rent and may treble that amount. The prevailing party shall be awarded attorney's fees and court costs.

(b) The remedy provided by this section shall not be construed to prohibit any other remedies available to any party affected by this section.

(c) This section shall not be construed to extend the time within which actions are required to be brought beyond the otherwise applicable limitation set forth in the Code of Civil Procedure.