Non est factum

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Contract law

Part of the common law series

Contract formation

Offer and acceptance · Mailbox rule Mirror image rule · Invitation to treat Firm offer · Consideration

Defenses against formation

Lack of capacity Duress · Undue influence Illusory promise · Statute of frauds Non est factum

Contract interpretation

Parol evidence rule Contract of adhesion Integration clause Contra proferentem

Excuses for non-performance

Mistake · Misrepresentation Frustration of purpose · Impossibility Impracticability · Illegality Unclean hands · Unconscionability Accord and satisfaction

Rights of third parties

Privity of contract Assignment · Delegation Novation · Third party beneficiary

Breach of contract

Anticipatory repudiation · Cover Exclusion clause · Efficient breach Fundamental breach

Remedies

Specific performance Liquidated damages Penal damages · Rescission

Quasi-contractual obligations

Promissory estoppel Quantum meruit

Related areas of law

Conflict of laws · Commercial law

Other common law areas

Tort law · Property law Wills, trusts and estates Criminal law · Evidence

v • d • e

Non est factum – Latin for "it is not [my] deed" – is a doctrine in contract law that allows a signing party to escape performance of the agreement. A claim of non est factum means that the signature on the contract was signed by mistake, without knowledge of its meaning, but was not done so negligently. A successful plea would make the contract void ab initio.

Non est factum is difficult to claim as it does not allow for negligence on the part of the signatory, i.e. failure to read a contract before signing it will not allow for non est factum, except in Canada using the precedent of Tilden Rent-A-Car Co. v. Clendenning. In a successful case, the fundamental basis of the signed contract must be completely different from what was intended. In Lloyds Bank v Waterhouse [1990] a father acted as a guarantor to his son's debt when purchasing a farm. The father was illiterate and signed the bank document under the belief that he was acting as the guarantor for the farm only, when the contract was actually for all the debt accumulated by the son. As he was illiterate, this was a mistake as to the document signed and the father was successful in claiming non est factum.

Another notable case on non est factum is Foster v Mackinnon (1869) LR 4 CP 704 where an elderly man signed a bill of exchange but was only shown the back of it. He was granted a new trial.^[1]

References

• Non est factum (Legal Glossary (English and Latin))
• Part 5: Mistake, Rectification & Misrepresentation at duhaime.org/LegalResources

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