What Is Non Est Factum?

Non est factum is a Latin phrase meaning “it is not my deed.” It’s a legal defence that allows someone to claim a contract or document they signed is void because they fundamentally misunderstood what they were signing. Essentially, you’re arguing that the document isn’t actually yours because you never truly agreed to it.

This defence is rare and difficult to prove. Courts are reluctant to let people escape contracts simply because they didn’t read carefully or misunderstood terms. 

Non est factum applies only in exceptional circumstances where the mistake was so fundamental that the person had no idea what they were actually signing.

Fundamental Mistake About the Document: You must have been mistaken about the very nature or character of the document itself, not just its terms or consequences. For example, thinking you’re signing a receipt when it’s actually a loan agreement, or believing you’re witnessing someone else’s signature when you’re actually signing as a guarantor.

Reasonable Explanation for the Mistake: You need a good reason for not knowing what you were signing. Valid reasons include serious illness, disability affecting comprehension, illiteracy, inability to read English, or vulnerability due to age or mental capacity. Simply being busy, careless, or not bothering to read doesn’t qualify.

Not Your Fault: You can’t claim non est factum if you were careless or negligent. If you could have discovered what you were signing by taking reasonable precautions, the defence fails. Courts expect people to read documents before signing them.

Courts apply a strict test for non est factum. You must prove that the document you signed is fundamentally different in nature from what you believed it to be, you weren’t careless in signing without understanding, and a reasonable person in your circumstances wouldn’t have understood what they were signing.

All three elements must be present. Missing even one means your defence fails.

If you’re pleading non est factum, you carry the burden of proving it. The law presumes that your signature on a document means you understood and agreed to it. Overcoming this presumption requires strong evidence showing why you genuinely didn’t understand what you were signing.

If non est factum succeeds, the contract is void; it is treated as if it never existed. You’re not bound by its terms, and you don’t need to perform any obligations under it. 

Don’t assume you’re stuck with a contract just because you signed it. In rare circumstances, the law provides relief. But you need proper legal guidance to determine if your situation qualifies.

Contact us at 416.901.9984 or info@pintoshekib.ca.