Texas Health and Safety Code - HEALTH & SAFETY § 597.041. Surrogate Decision-Makers

(a) If the results of an assessment conducted in accordance with Section 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:

(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  1.