Acts 1965, 59th Leg., p. 317, ch. 722, Sec. 1, eff. Jan. 1, 1966.

Amended by Acts 1991, 72nd Leg., ch. 561, Sec. 9, eff. Aug. 26, 1991; Acts 1995, 74th Leg., ch. 76, Sec. 5.95(27), eff. Sept. 1, 1995.