Texas Penal Code - PENAL § 7.03. Defenses Excluded

(1) that the actor belongs to a class of persons that by definition of the offense is legally incapable of committing the offense in an individual capacity; or

(2) that the person for whose conduct the actor is criminally responsible has been acquitted, has not been prosecuted or convicted, has been convicted of a different offense or of a different type or class of offense, or is immune from prosecution.