In State v. Mason, 980 S.W.2d 635 (Tex. Crim. App. 1998) the defendant-appellee argued that he could not be prosecuted for unlawful possession of a firearm by a felon because the date of his prior felony conviction was an element of the offense that occurred before the statute's effective date. See Mason, 980 S.W.2d at 641. The court of criminal appeals rejected Mason's argument and ruled that he was subject to prosecution under the existing version of the statute, reasoning that the concept of "element of an offense" does not include every issue to which the State has the burden of proof. See id. The court went on to state that only Mason's status as a felon, not the date upon which the prior felony conviction occurred, could be viewed as an element of the crime. See id. at 640.