A marriage annulment is a legal process whereby a marriage is dissolved and declared that it never existed. A divorce terminates a marriage-the annulment causes the parties to return to single, or unmarried status. Contrary to a popular myth, annulments are not reserved solely for marriages of shorter duration. In the U.S. the individual states regulate marriage, and one must meet the same residency requirements to file for an annulment as they would need if they filed for a divorce. When we speak of laws regulating marriage, we are speaking of 50 separate marriage codes. There are some universal aspects found in all 50 states, however. Marriages that get annulled have grounds that fall into one of two categories e.g. a void marriage or a voidable marriage.

The court will decree a marriage annulment and void marriage if grounds are proven. This court edict proclaims that despite a couple having gotten married, it should have never taken place. An example of a void marriage is one where someone marries another while still being married to a third person. Society calls that bigamy, and as such, regardless of the wishes of individuals involved, the marriage was void from the moment it was entered into.

A voidable marriage is one where certain conditions were present at the time they were married that qualify a marriage to go through the annulment process. An example of this might be where a couple has sexual relations and she gets pregnant. Her father threatens the boyfriend with a shotgun if he doesn't marry his daughter. Under threat and duress, the marriage occurs.

In general one of the following grounds for annulment must be met:

• The couple was married fraudulently. This can be due to the concealment of a criminal history, impotence, sexually transmitted diseases, etc.
• One of the parties didn't have the mental capacity to enter into a marriage contract. (i.e. due to drunkenness or mental disability-lack of awareness they were married).
• A close blood relationship exists between the two (consanguinity).
• One of the parties were married under duress, threat, or force.
• One party was still legally married when the current marriage occurred;
• One or both parties were not old enough to be married;
• One party was impotent and unable to consummate the marriage

Consanguinity- Some U.S. states forbid cousins to be married. Others are more lenient and only forbid people to marry their brothers, sisters, mothers, fathers, or aunts and uncles. Consanguinity is a ground for annulment in most states.
Bigamy- Bigamy is the act or condition of a person married to another person while still being lawfully married to a third person.
Polygamy- situation in which one man is either married to or involved in sexual relationships with a number of different women at one time, married or not.