California Code, Welfare and Institutions Code - WIC § 4655

(a) If the developmentally disabled person's parent, guardian, or conservator legally authorized to consent to such treatment does not respond within a reasonable time to the request of the director or his designee for the granting or denying of consent for such treatment, the director of a regional center or his designee may consent on behalf of the developmentally disabled person to such treatment and provide for such treatment to be given to such person.

(b) If the developmentally disabled person has no parent, guardian, or conservator legally authorized to consent to medical, dental, or surgical treatment on behalf of the person, the director of the regional center or his designee may consent to such treatment on behalf of the person and provide for such treatment to be given to the person.  The director of a regional center or his designee may thereupon also initiate, or cause to be initiated, proceedings for the appointment of a guardian or conservator legally authorized to consent to medical, dental, or surgical services.

(c) If the developmentally disabled person is an adult and has no conservator, consent to treatment may be given by someone other than the person on the person's behalf only if the developmentally disabled person is mentally incapable of giving his own consent.