(a) If the results of an assessment conducted in accordance with § 597.021 indicate that an adult client who does not have a legal guardian or a client under 18 years of age who has no parent, legal guardian, or managing or possessory conservator lacks the capacity to make a major medical or dental treatment decision, an adult surrogate from the following list, in order of descending preference, who has decision-making capacity and who is willing to consent on behalf of the client may consent to major medical or dental treatment on behalf of the client:
(1) an actively involved spouse;
(2) an actively involved adult child who has the waiver and consent of all other actively involved adult children of the client to act as the sole decision-maker;
(3) an actively involved parent or stepparent;
(4) an actively involved adult sibling who has the waiver and consent of all other actively involved adult siblings of the client to act as the sole decision-maker; and
(5) any other actively involved adult relative who has the waiver and consent of all other actively involved adult relatives of the client to act as the sole decision-maker.
(b) Any person who consents on behalf of a client and who acts in good faith, reasonably, and without malice is not criminally or civilly liable for that action.

(c) Consent given by the surrogate decision-maker is valid and competent to the same extent as if the client had the capacity to consent and had consented.
(d) Any dispute as to the right of a party to act as a surrogate decision-maker may be resolved only by a court of record under Title 3, Estates Code.