Mutual mistake

Mutual mistake

A mutual mistake occurs when the parties to a contract are both mistaken about the same material fact within their contract. They are at cross purposes. There is a meeting of the minds, but the parties are mistaken. Hence the contract is voidable. Collateral mistakes will not afford the right of rescission. A collateral mistake is one that "does not go to the heart" of the contract. For a mutual mistake to render a contract void, then the item the parties are mistaken about must be material (emphasis added). When there is a material mistake about a material aspect of the contract, the essential purpose of the contract, there is the question of the assumption of the risk. This risk may be determined contractually or according to custom. In American law, the Restatement (Second) of Contracts Sec. 154 deals with this scenario.