“Non est factum” — Literally, “it is not his deed,” or “the document did not follow his hand.” This is a defence in contract law. A contract can be voided if a person who signed it can show he did so in error, as a result of misrepresentation and while mistaken as to its nature and character.
To succeed, and avoid fulfilling the contract, the person claiming non est factum must show:
– He was not careless, and
– The document signed was different from the one he thought he was signing.
Misrepresentation is essential to a plea of non est factum. Not reading the document, not asking questions, and failing to obtain independent legal advice are all evidence of being careless in signing a document.