Precontract

A precontract is a legal contract that precedes another; in particular it refers to an existing promise of marriage with another. Such a precontract would legally nullify any later marriages into which either party entered. The practice was common in the Middle Ages, and the allegation of a precontract was the most common means of dissolving a marriage by the medieval ecclesiastical courts.

Richard III of England claimed his brother Edward IV had entered into a marriage precontract with Lady Eleanor Talbot prior to Edward's later marriage to Elizabeth Woodville. The claim is now largely, though not universally, regarded to be false; if true, it would have meant that Edward's sons by Elizabeth, the 'Princes in the Tower', would have been illegitimate and Richard, rather than they, would have inherited the throne upon Edward's death.