Cal. Prob. Code § 4782

A health care provider who honors a request regarding resuscitative measures is not subject to criminal prosecution, civil liability, discipline for unprofessional conduct, administrative sanction, or any other sanction, as a result of his or her reliance on the request, if the health care provider (a) believes in good faith that the action or decision is consistent with this part, and (b) has no knowledge that the action or decision would be inconsistent with a health care decision that the individual signing the request would have made on his or her own behalf under like circumstances.