California Code, Civil Code - CIV § 1746.1

(a) A person may not sell or rent a video game that has been labeled as a violent video game to a minor.

(b) Proof that a defendant, or his or her employee or agent, demanded, was shown, and reasonably relied upon evidence that a purchaser or renter of a violent video game was not a minor or that the manufacturer failed to label a violent video game as required pursuant to Section 1746.2 shall be an affirmative defense to any action brought pursuant to this title. That evidence may include, but is not limited to, a driver's license or an identification card issued to the purchaser or renter by a state or by the Armed Forces of the United States.

(c) This section shall not apply if the violent video game is sold or rented to a minor by the minor's parent, grandparent, aunt, uncle, or legal guardian.