non est factum

Non est factum is a claim that a party signing a document was unaware of its true nature and thus ought not be bound to it in contract law. The misunderstanding must relate to the fundamental nature of the document. The misapprehension may not arise by fraud, misrepresentation or a form of mistake.

The term Non est Factum is derived from the Latin "Not his document". The person signing the document must not have been negligent prior to signing the contract in order for relief to be available.

The cause of action arose primarily for the benefit of the illiterate.

Usage: The claimant sought to relieve himself of his obligations under the contract by claiming non est factum on the basis that he was informed that the document was a transfer of his house rather than a mortgage.

Related Words: mistake of fact; mistake of law; mutual mistake; unilateral mistake; contract; rectification; instrument; misrepresentation; fraud.