Cal. Probate Code § 2353

(a) Subject to subdivision (b), the guardian has the same right as a parent having legal custody of a child to give consent to medical treatment performed upon the ward and to require the ward to receive medical treatment. (b) Except as provided in subdivision (c), if the ward is 14 years of age or older, no surgery may be performed upon the ward without either (1) the consent of both the ward and the guardian or (2) a court order obtained pursuant to Section 2357 specifically authorizing such treatment. (c) The guardian may consent to surgery to be performed upon the ward, and may require the ward to receive the surgery, in any case where the guardian determines in good faith based upon medical advice that the case is an emergency case in which the ward faces loss of life or serious bodily injury if the surgery is not performed. In such a case, the consent of the guardian alone is sufficient and no person is liable because the surgery is performed upon the ward without the ward’s consent. (d) Nothing in this section requires the consent of the guardian for medical or surgical treatment for the ward in any case where the ward alone may consent to such treatment under other provisions of law.