Sec. 101.053.  CONTRACT REQUIRING OR PROHIBITING LABOR UNION MEMBERSHIP VOID.  A contract is void if it requires that, to work for an employer, employees or applicants for employment:
(1)  must be or may not be members of a labor union;  or
(2)  must remain or may not remain members of a labor union.
Acts 1993, 73rd Leg., ch. 269, Sec. 1, eff. Sept. 1, 1993.