ABSTRACT
This chapter examines situations where an agreement is affected by a mistake on the part of one or both parties. It discusses the situations in which a putative contract may be regarded as never having come into existence, or may be brought to an end, as a result of a mistake by either or both of the parties. One of the examples of operative mistake is where the parties have attempted to make a ‘contract’ about something that had ceased to exist at the time the contract is made. The effect of an operative common mistake at common law is to render the contract void ab initi. ‘Mutual mistake’ refers to the situation where the parties are at cross-purposes but neither side is aware of this when they purport to make a contract. ‘Unilateral mistake’ refers to the situation where the agreement is ‘negatived’, because one party is aware that the other is mistaken about an aspect of the contract.
