Non est factum in the 21st Century

28 Jun 2012
Alasdair Taylor

Pottering around in some of the dustier corners of the law of contract this morning, I happened on the doctrine of non est factum (“it is not my deed”), a species of mistake I haven’t given any thought to since law school. The doctrine was developed by the English courts to protect those who signed legal documents mistakenly.  Where the doctrine applies, a person who mistakenly signs a contract or deed is not bound thereby.

The classic situation involves a blind person who executes a document after it had been incorrectly read to him or her.  As well as the blind, the doctrine may protect anyone who – through no fault of their own –  has no understanding of the meaning and effects of a document: the ill, the infirm, those of low intelligence, the seriously under-educated, and those unable to understand the language of the document.

In addition, the doctrine may protect those who have been tricked.  In one case, it applied where man signed some promissory notes on the basis of a fraudulent misrepresentation that he was witnessing rather than executing them.

The doctrine is rather limited in scope, and rarely appears in the law reports. It won’t protect a negligent or careless signatory, nor one who makes non-fundamental mistake about the nature of the document that he or she is signing.  In most cases simple ignorance about the contents of the document will not bring the doctrine into play.

Non est factum has its roots in the late Sixteenth Century.  But how might it apply to contracts made over the internet?  I think there are a few different issues.

First, it’s not uncommon practice to summarise the terms of an internet contract, to help users understand what they are signing up to.  It’s conceivable that the doctrine might apply where there is a grossly misleading summary of the terms – one amounting to a fraudulent misrepresentation.  A summary that merely skipped some important feature(s) of the contract would not, I’m think, have the same effect.

Second, users who suffer from some disability that inhibits access to terms and conditions may be able to rely upon the doctrine, particularly where the website operator has not made the document accessible to disabled users.  Yet another argument – if one were needed – for  ensuring that your websites meet accessibility standards.

Third, those users who are inherently unable to understand the implications of signing up to a document online, whatever the reason, may not be bound thereby.  There will be cross-over here with the rules on mental capacity.  There’s not a great deal an operator can do about this possibility.

Fourth, the internet is international, and a document that is not in a language known to the user might also be subject to the doctrine. I would speculate that the doctrine would only stretch this far where the user is unable to appreciate the possible implications of signing-up to a foreign language document, and might therefore fall under the above category in any event.

This is all, of course, speculation. If you know of any actual cases where the non est factum doctrine has been applied to a contract entered into online, please let me know.


Non Est Factum has lots of manifestations.
Maxim: Actus me invito factus, non est meus actus. An act done by me against my will, is not my act. So, contracts signed under force, threat, coersion, ignorance, etc are void or voidable.
He who does not claim his rights, has none. Non Est Factum is a claim, or potential claim, ex post facto.

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