California Code, Health and Safety Code - HSC § 11376.5

(a) Notwithstanding any other law, it shall not be a crime for a person to be under the influence of, or to possess for personal use, a controlled substance, controlled substance analog, or drug paraphernalia, if that person, in good faith, seeks medical assistance for another person experiencing a drug-related overdose that is related to the possession of a controlled substance, controlled substance analog, or drug paraphernalia of the person seeking medical assistance, and that person does not obstruct medical or law enforcement personnel. No other immunities or protections from arrest or prosecution for violations of the law are intended or may be inferred.

(b) Notwithstanding any other law, it shall not be a crime for a person who experiences a drug-related overdose and who is in need of medical assistance to be under the influence of, or to possess for personal use, a controlled substance, controlled substance analog, or drug paraphernalia, if the person or one or more other persons at the scene of the overdose, in good faith, seek medical assistance for the person experiencing the overdose. No other immunities or protections from arrest or prosecution for violations of the law are intended or may be inferred.

(c) This section shall not affect laws prohibiting the selling, providing, giving, or exchanging of drugs, or laws prohibiting the forcible administration of drugs against a person's will.

(d) Nothing in this section shall affect liability for any offense that involves activities made dangerous by the consumption of a controlled substance or controlled substance analog, including, but not limited to, violations of Section 23103 of the Vehicle Code as specified in Section 23103.5 of the Vehicle Code, or violations of Section 23152 or 23153 of the Vehicle Code.

(e) For the purposes of this section, “drug-related overdose” means an acute medical condition that is the result of the ingestion or use by an individual of one or more controlled substances or one or more controlled substances in combination with alcohol, in quantities that are excessive for that individual that may result in death, disability, or serious injury. An individual's condition shall be deemed to be a “drug-related overdose” if a reasonable person of ordinary knowledge would believe the condition to be a drug-related overdose that may result in death, disability, or serious injury.