A marriage is void from the time its nullity is declared by a court of competent jurisdiction if either party thereto: 1. Is under the age of legal consent, which is eighteen years; 2. Is incapable of consenting to a marriage for want of understanding; 3. Is incapable of entering into the married state from physical cause; 4. Consent to such marriage by reason of force, duress or fraud; 5. Has been incurably mentally ill for a period of five years or more.
New York Legal Code