Tex. Property Code § 113.029

(a) Notwithstanding the breadth of discretion granted to a trustee in the terms of the trust, including the use of terms such as "absolute," "sole," or "uncontrolled," the trustee shall exercise a discretionary power in good faith and in accordance with the terms and purposes of the trust and the interests of the beneficiaries.

(b) Subject to Subsection (d), and unless the terms of the trust expressly indicate that a requirement provided by this subsection does not apply:

(1) a person, other than a settlor, who is a beneficiary and trustee, trustee affiliate, or discretionary power holder of a trust that confers on the trustee a power to make discretionary distributions to or for the trustee's, the trustee affiliate's, or the discretionary power holder's personal benefit may exercise the power only in accordance with an ascertainable standard relating to the trustee's, the trustee affiliate's, or the discretionary power holder's individual health, education, support, or maintenance within the meaning of Section 2041(b)(1)(A) or 2514(c)(1), Internal Revenue Code of 1986; and

(2) a trustee may not exercise a power to make discretionary distributions to satisfy a legal obligation of support that the trustee personally owes another person.

(c) A power the exercise of which is limited or prohibited by Subsection (b) may be exercised by a majority of the remaining trustees whose exercise of the power is not limited or prohibited by Subsection (b). If the power of all trustees is limited or prohibited by Subsection (b), the court may appoint a special fiduciary with authority to exercise the power.

(d) Subsection (b) does not apply to:

(1) a power held by the settlor's spouse who is the trustee of a trust for which a marital deduction, as defined by Section 2056(b)(5) or 2523(e), Internal Revenue Code of 1986, was previously allowed;

(2) any trust during any period that the trust may be revoked or amended by its settlor; or

(3) a trust if contributions to the trust qualify for the annual exclusion under Section 2503(c), Internal Revenue Code of 1986.

(e) In this section, "discretionary power holder" means a person who has the sole power or power shared with another person to make discretionary decisions on behalf of a trustee with respect to distributions from a trust.