A person may not discharge or in any other manner discriminate against an employee because the employee has:
(1) filed a workers' compensation claim in good faith;
(2) hired a lawyer to represent the employee in a claim;
(3) instituted or caused to be instituted in good faith a proceeding under Subtitle A; or
(4) testified or is about to testify in a proceeding under Subtitle A.
Acts 1993, 73rd Leg., ch. 269, § 1, eff. Sept. 1, 1993.