An annulment is one way to end a marriage or a civil union. There is sometimes a misconception that an annulment is a "quickie divorce" and anyone has a right to request one; however, annulments are only available under certain narrow circumstances -- and the other party always has the right to contest the proceeding.
An annulment is a legal proceeding to have a state court declare that a marriage or civil union never existed. It retroactively voids the proceeding that purported to establish a legal union. Each state has its own laws that establish the grounds for an annulment. The person petitioning the court for an annulment must state facts that support one of those grounds. Some of the most common grounds for an annulment are bigamy, insanity, fraud, duress, incapacity and inability to have sexual relations.
If one of the parties files an answer with the court to the other party's petition for annulment, the proceeding is contested. Contesting the annulment means that one party challenges the material representations made by the other party in the petition.
In most states, filing an answer to contest a petition for annulment will cause the court to automatically schedule the case for a hearing. In these states, a contested annulment cannot be decided based on the written documents alone. Therefore, the purpose of the hearing is to decide if valid grounds for an annulment exist and the burden is on the person seeking the annulment to prove that they do.
Contesting an annulment does not mean that you cannot apply for a divorce. Rather, an annulment will extinguish any rights either party has to marital distribution of property, alimony or other benefits of marriage or a civil union. Some people object to the idea of a marriage or union being wiped away as if it never existed and prefer divorce over annulment. If the court finds in favor of the party contesting the annulment, the parties are deemed to have a legal marriage or civil union and the only way to terminate it is through a divorce proceeding.