California Code, Probate Code - PROB § 4716

(a) If a patient lacks the capacity to make a health care decision, the patient's domestic partner shall have the same authority as a spouse has to make a health care decision for his or her incapacitated spouse. This section may not be construed to expand or restrict the ability of a spouse to make a health care decision for an incapacitated spouse.

(b) For the purposes of this section, the following definitions shall apply: