All states agree that some marriages are prohibited or illegal, and most also agree that if certain circumstances exist at the time of the marriage, the innocent spouse is entitled to erase the marriage. Divorce ends a marriage. Annulment renders it void. Legally, it never happened. Most rules regarding annulment address whether or not the marriage qualifies for this special treatment. This is called having grounds for annulment.
Factual Grounds
Some grounds for annulment are provable with facts. All states agree that individuals related by blood--called consanguinity under the law--cannot marry and if they do, it is grounds for annulment because the marriage should never have occurred in the first place. The only variation between states is how close of a blood tie you might have with your spouse. Some states include step relationships. Minors who marry younger than their state's legal age are eligible for annulment, but states differ somewhat with this rule depending on whether or not the couple married with or without their parents' consent. Some states will annul such a marriage even if the teenagers went to a different state to get married, then returned home. Bigamous marriages can also be annulled because they are not legal.
Other Grounds
Fraud is considered a ground for annulment in most states. The innocent spouse has to prove to the court that he was lied to and that he married believing in that lie. Coercion can nullify a marriage if the spouse can prove he was forced into the union. An individual can usually have his marriage annulled if he can prove that he was intoxicated or under the influence of drugs at the time of the wedding.
Deadlines
A common misconception is that the length of a marriage governs whether or not it can be annulled. Duration of a marriage is not grounds for annulment in any state, but some grounds do have built-in deadlines. For instance, in cases of fraud, if you continue to live with your spouse after you learn that you were lied to, you may not be able to have your marriage annulled. Most states have rules that govern how long you can continue to live with your spouse after you have discovered grounds for annulment.
Assets and Debts
When a marriage lasts one or more years before the qualifying reason for annulment is discovered, spouses may have incurred joint debt during that time. According to Nolo, a website designed to help readers understand legal issues that may affect their lives, most states have statutes that allow assets and debts to be divided in an annulment just as they would be in a divorce.
Children
Nolo also says that children conceived during the term of a marriage that has been annulled are considered legitimate and the non-custodial parent is held just as liable for child support as if the marriage had ended by divorce. However, judges may require stronger proof of the grounds to annul a marriage when children are involved.
