A void marriage is a marriage that is unlawful or invalid under the laws of the jurisdiction where it is entered. A void marriage is invalid from its beginning, and is generally treated under the law as if it never existed and requires no formal action to terminate. In some jurisdictions a void marriage must still be terminated by annulment, or an annulment may be required to remove any legal impediment to a subsequent marriage. A marriage that is entered into in good faith, but that is later found to be void, may be recognized as a putative marriage and the spouses as putative spouses, with certain rights granted by statute or common law, notwithstanding that the marriage itself is void.
Void marriages are distinct from those marriages that can be canceled at the option of one of the parties, but otherwise remain valid. Such a marriage is voidable, meaning that it is subject to cancellation through annulment if contested in court.
According to Paul J. Goda, the distinction between void and voidable marriages arose in the context of a jurisdictional dispute between the civil and ecclesiastical courts. The civil courts held jurisdiction over property matters, while the church retained jurisdiction over the validity of marriages. There was an overlap in cases of inheritance where it was necessary to determine the legitimacy of putative heirs. With the Reformation, the focus shifted from marriage as a religious matter to that of a civil contract, according to Goda: "Early American courts accepted the distinction between canonical and civil disabilities as the rationale for void (civilly disabled) and voidable (canonically disabled) marriages." Colonial courts followed the Common Law view in looking to the capacity of the parties to enter into a legally binding contract.
In general, a marriage is void (as opposed to voidable) if:
Most jurisdictions recognise the validity of marriages performed in another jurisdiction. However, a jurisdiction where the parties to the marriage normally reside may not recognise a "foreign" marriage. Common reasons for a court to find a marriage void ab initio are that the marriage is incestuous, polygamous, a same-sex marriage, or a group marriage.
Under the Domestic Relations Law of New York State, all incestuous marriages are void, but this does not include cousin marriages of any degree:
Under the law of England and Wales, a void marriage is "one that is considered never to have taken place, whatever procedure may have been followed by the people concerned." Marriage Act 1949 has been discussed in this context. The relevant legislation is sections 11 to 16 of the Matrimonial Causes Act 1973 which has been amended by the Divorce (Religious Marriages) Act 2002 and the Marriage (Same Sex Couples) Act 2013 among others.
Grounds for determining a marriage void as against public policy include consanguinity, one of the parties is under the age of sixteen, or that at the time of the marriage either party was already lawfully married. If a marriage was not legally valid, the law says that it never existed.