(1) If a patient who is of or over the age of 18 years does not have capacity to give informed consent to medical treatment, the medical treatment may be administered to the patient with the consent of the first person of the following listed below who, in the circumstances, is reasonably available, willing and able to make a decision concerning the proposed medical treatment—
(a) a person appointed by the patient under section 5A of the Medical Treatment Act 1988 ;
(b) a person appointed by VCAT to make decisions concerning the proposed medical treatment;
(c) a person appointed under a guardianship order within the meaning of the Guardianship and Administration Act 1986 with power to make decisions concerning the proposed medical treatment;
(d) a person appointed by the patient (before the patient became incapable of giving informed consent) as an enduring guardian within the meaning of the Guardianship and Administration Act 1986 with power to make decisions concerning the proposed medical treatment;
(e) the authorised psychiatrist, subject to section 76.
(2) If a patient who is under the age of 18 years does not have capacity to give informed consent to medical treatment, the medical treatment may be administered to the patient with the consent of—
(a) a person who, in relation to the patient, has the legal authority to consent to medical treatment and who, in the circumstances, is reasonably available, willing and able to make a decision concerning the proposed treatment; or
(b) the authorised psychiatrist, subject to section 76 and if a person specified under paragraph (a) is not reasonably available or not willing and able to make a decision concerning the proposed medical treatment.