California Code, Probate Code - PROB § 2354

(a) If the conservatee has not been adjudicated to lack the capacity to give informed consent for medical treatment, the conservatee may consent to his or her medical treatment.  The conservator may also give consent to the medical treatment, but the consent of the conservator is not required if the conservatee has the capacity to give informed consent to the medical treatment, and the consent of the conservator alone is not sufficient under this subdivision if the conservatee objects to the medical treatment.

(b) The conservator may require the conservatee to receive medical treatment, whether or not the conservatee consents to the treatment, if a court order specifically authorizing the medical treatment has been obtained pursuant to Section 2357.

(c) The conservator may consent to medical treatment to be performed upon the conservatee, and may require the conservatee to receive the medical treatment, in any case where the conservator determines in good faith based upon medical advice that the case is an emergency case in which the medical treatment is required because (1) the treatment is required for the alleviation of severe pain or (2) the conservatee has a medical condition which, if not immediately diagnosed and treated, will lead to serious disability or death.  In such a case, the consent of the conservator alone is sufficient and no person is liable because the medical treatment is performed upon the conservatee without the conservatee's consent.