Cal. Probate Code § 1881

(a) A conservatee shall be deemed unable to give informed consent to any form of medical treatment pursuant to Section 1880 if, for all medical treatments, the conservatee is unable to respond knowingly and intelligently to queries about medical treatment or is unable to participate in a treatment decision by means of a rational thought process. (b) In order for a court to determine that a conservatee is unable to respond knowingly and intelligently to queries about his or her medical treatment or is unable to participate in treatment decisions by means of a rational thought process, a court shall do both of the following: (1) Determine that, for all medical treatments, the conservatee is unable to understand at least one of the following items of minimum basic medical treatment information: (A) The nature and seriousness of any illness, disorder, or defect that the conservatee has or may develop. (B) The nature of any medical treatment that is being or may be recommended by the conservatee’s health care providers. (C) The probable degree and duration of any benefits and risks of any medical intervention that is being or may be recommended by the conservatee’s health care providers, and the consequences of lack of treatment. (D) The nature, risks, and benefits of any reasonable alternatives. (2) Determine that one or more of the mental functions of the conservatee described in subdivision (a) of Section 811 is impaired and that there is a link between the deficit or deficits and the conservatee’s inability to give informed consent. (c) A deficit in the mental functions listed in subdivision (a) of Section 811 may be considered only if the deficit by itself, or in combination with one or more other mental function deficits, significantly impairs the conservatee’s ability to understand the consequences of his or her decisions regarding medical care. (d) In determining whether a conservatee’s mental functioning is so severely impaired that the conservatee lacks the capacity to give informed consent to any form of medical treatment, the court may take into consideration the frequency, severity, and duration of periods of impairment. (e) In the interest of minimizing unnecessary expense to the parties to a proceeding, paragraph (2) of subdivision (b) shall not apply to a petition pursuant to Section 1880 wherein the conservatee, after notice by the court of his or her right to object which, at least, shall include an interview by a court investigator pursuant to Section 1826 prior to the hearing on the petition, does not object to the proposed finding of incapacity, or waives any objections.