California Code, Civil Code - CIV § 1939.15

(a) In the absence of express permission granted by the renter subsequent to damage to, or loss of, the rented vehicle, a rental company shall not seek to recover any portion of a claim arising out of damage to, or loss of, the vehicle by processing a credit card charge or causing a debit or block to be placed on the renter's credit card account.

(b) A rental company shall not engage in any unfair, deceptive, or coercive tactics in attempting to recover or in recovering on any claim arising out of damage to, or loss of, the rented vehicle.