unilateral mistake

Unilateral mistake is similar to mutual mistake, except that only one party is operating under a misconception of facts, and the other party is aware of their misunderstanding or ought to be taken as being aware of it. The mistake must relate to a condition of the contract rather than a warranty. Misconceptions that relate to quality are not sufficient for a successful claim for unilateral mistake.

Usage: Specific performance of the contract was declined by the court on the basis that the unilateral mistake related to the age of the goods rather than their nature.

Related Words: mistake of fact; mistake of law; mutual mistake; contract; rectification; non est factum.