Tex. Transportation Code § 451.757

(a) A written agreement ratified under this subchapter preempts, during the term of the agreement and to the extent of any conflict, all contrary state statutes, local ordinances, executive orders, civil service provisions, or rules adopted by the state, by the authority or another political subdivision, or by a division or agent of the authority or other political subdivision, such as a personnel board or a civil service commission.

(b) An agreement ratified under this subchapter may not interfere with the right of a member of a bargaining unit to pursue allegations of discrimination based on race, creed, color, national origin, religion, age, sex, or disability with the Commission on Human Rights or the federal Equal Employment Opportunity Commission or to pursue affirmative action litigation.