Added by Acts 1979, 66th Leg., p. 1851, ch. 751, Sec. 1, eff. Sept. 1, 1979. Sec. 1 amended by Acts 1983, 68th Leg., p. 1586, ch. 303, Sec. 7, eff. Jan. 1, 1984.

Amended by Acts 1987, 70th Leg., ch. 721, Sec. 1, eff. Sept. 1, 1987. Sec. 1 amended by Acts 1989, 71st Leg., ch. 603, Sec. 1, eff. Sept. 1, 1989;

Acts 1991, 72nd Leg., 2nd C.S., ch. 10, Sec. 7.01, eff. Dec. 1, 1991.

Acts 2015, 84th Leg., R.S., Ch. 770 (H.B. 2299), Sec. 2.09, eff. January 1, 2017.