An annulment is a lawsuit to have a court declare a marriage was invalid and the parties were never in fact married. The grounds for an annulment vary from state to state but typically include:

• the person seeking the annulment (the petitioner) was under age (18 years, for example) and did not have parental consent or a court order;

• the person seeking the annulment (the petitioner) was under the influence of drugs or alcohol and did not have the capacity to consent to the marriage;

• either party, for physical or mental reasons, was permanently impotent at the time of the marriage and the other party was not aware of the impotency;

• the other party used fraud, duress, or force to induce the petitioner to enter into the marriage;

• at the time of the marriage the petitioner did not have the mental capacity to consent to marriage or to understand the nature of the marriage ceremony because of a mental disease or defect;

• the other party was divorced from a third party within the 30-day period preceding the date of the marriage ceremony, and at the time of the marriage ceremony the petitioner did not know, and a reasonably prudent person would not have known, of the divorce; and

• the marriage ceremony took place before any waiting period (72 hours, for example) following issuance of the marriage license.

An annulment on any ground is often available only if the parties did not live together (cohabit) after the party seeking the annulment was no longer under the influence of drugs or alcohol, or learned of the facts that are the basis for the annulment sought. A marriage subject to annulment is often said to be a nullity, void, or void ab initio (void from the beginning).

The grounds for an annulment are usually found in a state’s statutes—often in the family code.

In Connecticut, an annulment is a legal proceeding that seeks to establish that a marriage was never valid from the start. The grounds for annulment in Connecticut include: one party being underage without parental consent or a court order; lack of capacity to consent due to intoxication from drugs or alcohol; permanent impotence unknown to the other party at the time of marriage; fraud, duress, or force used to obtain marriage consent; lack of mental capacity to understand the marriage due to a mental condition; the other party having been divorced within 30 days prior to the marriage without the petitioner's knowledge; and non-compliance with any statutory waiting period after the marriage license was issued. It is important to note that if the couple cohabited after the impediment to a valid marriage was removed or discovered, annulment might not be granted. These grounds are typically codified in the state's family law statutes. An annulled marriage is considered void or 'void ab initio,' meaning it is treated as if it never existed. Individuals seeking an annulment are advised to consult with an attorney to understand their rights and the legal process involved.