38 CFR § 3.207 - Void or annulled marriage.
Proof that a marriage was void or has been annulled should consist of:
(b)Annulled. A copy or abstract of the decree of annulment. A decree regular on its face will be accepted unless there is reason to question the basic authority of the court to render annulment decrees or there is evidence indicating that the annulment may have been obtained through fraud by either party or by collusion.