Tex. Lab. Code § 21.055 : LABOR CODE — PROTECTION OF LABORERS — EMPLOYMENT DISCRIMINATION — EMPLOYMENT DISCRIMINATION — UNLAWFUL EMPLOYMENT PRACTICES — Retaliation

An employer, labor union, or employment agency commits an unlawful employment practice if the employer, labor union, or employment agency retaliates or discriminates against a person who, under this chapter:

(1) opposes a discriminatory practice;
(2) makes or files a charge;
(3) files a complaint; or
(4) testifies, assists, or participates in any manner in an investigation, proceeding, or hearing.

Tex. Lab. Code § 21.055

Acts 1993, 73rd Leg., ch. 269, Sec. 1, eff. 9/1/1993.