California Civil Code, Sec. 1936(e)(-(f)
(e)
(1) Except as provided in subdivision (f), a damage waiver shall provide or, if not expressly stated in writing, shall be deemed to provide that the renter has no liability for a damage, loss, loss of use, or a cost or expense incident thereto.
(2) Except as provided in subdivision (f), every limitation, exception, or exclusion to a damage waiver is void and unenforceable.
(f) A rental company may provide in the rental contract that a damage waiver does not apply under any of the following circumstances:
(1) Damage or loss results from an authorized driver's (A) intentional, willful, wanton, or reckless conduct, (B) operation of the vehicle under the influence of drugs or alcohol in violation of Section 23152 of the Vehicle Code, (C) towing or pushing anything, or (D) operation of the vehicle on an unpaved road if the damage or loss is a direct result of the road or driving conditions.
(2) Damage or loss occurs while the vehicle is (A) used for commercial hire, (B) used in connection with conduct that could be properly charged as a felony, (C) involved in a speed test or contest or in driver training activity, (D) operated by a person other than an authorized driver, or (E) operated outside the United States.
(3) An authorized driver who has (A) provided fraudulent information to the rental company, or (B) provided false information and the rental company would not have rented the vehicle if it had instead received true information.