Cal. Probate Code § 4712

(a) If a patient lacks the capacity to make a health care decision, the following legally recognized health care decisionmakers may make health care decisions on the patient’s behalf, in the following descending order of priority: (1) The patient’s surrogate selected pursuant to Section 4711. (2) The patient’s agent pursuant to an advance health care directive or a power of attorney for health care. (3) The conservator or guardian of the patient having the authority to make health care decisions for the patient. (b) Except as set forth in Section 4715, if a patient lacks the capacity to make a health care decision, but does not have a legally recognized health care decisionmaker pursuant to subdivision (a), a health care provider or a designee of the health care facility caring for the patient may choose a surrogate to make health care decisions on the patient’s behalf, as appropriate in the given situation. The patient’s surrogate shall be an adult who has demonstrated special care and concern for the patient, is familiar with the patient’s personal values and beliefs to the extent known, and is reasonably available and willing to serve. A surrogate may be chosen from any of the following persons: (1) The spouse or domestic partner of the patient. (2) An adult child of the patient. (3) A parent of the patient. (4) An adult sibling of the patient. (5) An adult grandchild of the patient. (6) An adult relative or close personal friend.