California Code, Labor Code - LAB § 1194

(a) Notwithstanding any agreement to work for a lesser wage, any employee receiving less than the legal minimum wage or the legal overtime compensation applicable to the employee is entitled to recover in a civil action the unpaid balance of the full amount of this minimum wage or overtime compensation, including interest thereon, reasonable attorney's fees, and costs of suit.

(b) The amendments made to this section by Chapter 825 of the Statutes of 1991 shall apply only to civil actions commenced on or after January 1, 1992.