A person is guilty of unlawfully solemnizing a marriage when:
1.  Knowing  that he is not authorized by the laws of this state to do
  so, he performs a marriage ceremony or presumes to solemnize a marriage;
  or
2. Being authorized by the laws of  this  state  to  perform  marriage
  ceremonies  and  to solemnize marriages, he performs a marriage ceremony
  or solemnizes a  marriage  knowing  that  a  legal  impediment  to  such
  marriage exists.
Unlawfully solemnizing a marriage is a class A misdemeanor.
Structure New York Laws
Title O - Offenses Against Marriage, the Family, and the Welfare of Children and Incompetents
Article 255 - Offenses Affecting the Marital Relationship
255.00 - Unlawfully Solemnizing a Marriage.
255.05 - Unlawfully Issuing a Dissolution Decree.
255.10 - Unlawfully Procuring a Marriage License.
255.20 - Unlawfully Procuring a Marriage License, Bigamy, Adultery: Defense.
255.25 - Incest in the Third Degree.
255.26 - Incest in the Second Degree.