Cal. Probate Code § 4711

(a) A patient may designate an adult as a surrogate to make health care decisions by personally informing the supervising health care provider or a designee of the health care facility caring for the patient. The designation of a surrogate shall be promptly recorded in the patient’s health care record. (b) Unless the patient specifies a shorter period, a surrogate designation under subdivision (a) is effective only during the course of treatment or illness or during the stay in the health care institution when the surrogate designation is made, or for 60 days, whichever period is shorter. (c) The expiration of a surrogate designation under subdivision (b) does not affect any role the person designated under subdivision (a) may have in making health care decisions for the patient under any other law or standards of practice. (d) Notwithstanding Section 4685, if the patient has designated an agent under a power of attorney for health care, the surrogate designated under subdivision (a) has priority over the agent for the period provided in subdivision (b), but the designation of a surrogate does not revoke the designation of an agent unless the patient communicates the intention to revoke in compliance with subdivision (a) of Section 4695.