Tex. Penal Code § 12.04
(a) Felonies are classified according to the relative seriousness of the offense into five categories:
Acts 1973, 63rd Leg., p. 883, ch. 399, Sec. 1, eff. Jan. 1, 1974.
Amended by Acts 1973, 63rd Leg., p. 1125, ch. 426, art. 2, Sec. 3, eff. Jan. 1, 1974;
Acts 1993, 73rd Leg., ch. 900, Sec. 1.01, eff. Sept. 1, 1994.