(a) An individual commits an offense if:
(1) he is legally married and he:
(A) purports to marry or does marry a person other than his spouse in this state, or any other state or foreign country, under circumstances that would, but for the actor's prior marriage, constitute a marriage; or
(B) lives with a person other than his spouse in this state under the appearance of being married; or
(2) he knows that a married person other than his spouse is married and he:
(A) purports to marry or does marry that person in this state, or any other state or foreign country, under circumstances that would, but for the person's prior marriage, constitute a marriage; or
(B) lives with that person in this state under the appearance of being married.
(b) For purposes of this section, "under the appearance of being married" means holding out that the parties are married with cohabitation and an intent to be married by either party.
(c) It is a defense to prosecution under Subsection (a)(1) that the actor reasonably believed at the time of the commission of the offense that the actor and the person whom the actor married or purported to marry or with whom the actor lived under the appearance of being married were legally eligible to be married because the actor's prior marriage was void or had been dissolved by death, divorce, or annulment. For purposes of this subsection, an actor's belief is reasonable if the belief is substantiated by a certified copy of a death certificate or other signed document issued by a court.
(d) For the purposes of this section, the lawful wife or husband of the actor may testify both for or against the actor concerning proof of the original marriage.
(e) An offense under this section is a felony of the third degree, except that if at the time of the commission of the offense, the person whom the actor marries or purports to marry or with whom the actor lives under the appearance of being married is:
(1) 17 years of age, the offense is a felony of the second degree; or
(2) 16 years of age or younger, the offense is a felony of the first degree.