There are 8 circumstances that legally annul a marriage. These are:
Incest: Close blood relatives participating in a marriage or domestic partnership.
Bigamy: A spouse legally married or in a domestic partnership with someone else.
Age at Time of Marriage or Domestic Partnership: The filing party being 18 years old or younger at time of marriage or domestic partnership.
Prior existing marriage or domestic partnership: This is different from bigamy because the spouse is not knowingly committing bigamy due to the prior spouse being absent or thought dead for 5 years.
Unsound Mind: Either party unable or unaware of what marriage or a domestic partnership entails.
Fraud: The omission of the lie, or fraud, must have led the spouse to marry (like marry for a green card or inability to have children).
Force: Either party entered in the marriage by force or coercion of any kind.
Physical Incapacity: If either of the spouses is found to be incurably incapable of consummating the marriage.