Annulment

The statutes or legislation that determine the impediments to a valid marital contract are not uniform from state to state, and the grounds for annulment vary from one jurisdiction to another. In every case, however, these grounds must be clear, strong, and convincing before an annulment court will issue a decree of nullity following legal proceedings to liquidate a marriage. While the rule of law changes from one jurisdiction to another, some reasons why parties are unable to exchange marital consent include:

1. failure to follow legal format, such as not obtaining a marriage license or neglecting to fulfill other statutory prohibitions;
2. being underage—there is a fixed marriageable age that must be respected;
3. gender—most societies permit only heterosexuals to marry;
4. consanguinity—a marriage would be considered "incestuous and void" if the parties were related by blood, that is, ancestors and descendants such as father and daughter, brothers and sisters, uncles and nieces, aunts and nephews;
5. affinity—a relationship established by marriage, such as stepbrother and stepsister;
6. impotency—the incapacity to perform the act of sexual intercourse;
7. duress (force and fear)—a valid marriage requires free and willing consent of both male and female;
8. fraud (deception)—both parties must intend to assume the contractual obligations; and
9. mental disorder or mental deficiency— persons must possess the ability to understand the nature and consequences of the marriage ceremony.

If any of these impediments were present at the time of the marriage and proven in a court of law, a decree of nullity would be issued indicating that no marriage existed.