Non est factum is a Latin phrase that means, "It is not his/her deed." It is used in contract law as a special defense allowing an individual to not fulfill the stipulations in a contract they have signed.

History of Non Est Factum

The doctrine is over a century old and was created for several reasons, including:

  • To apply in situations where people were illiterate during that time in history and were incapable of reading what they were signing. 
  • As a remedy for forged documents.
  • To address fraudulent representations.
  • To apply in situations where someone had no idea what they were signing. 

Today, allowing a plea of non est factum is well-established and in use in several common law countries. 

The Paradox in Contract Law: Non Est Factum

The Latin phrase "consensus ad idem" is referred to when an enforceable agreement between two parties occurs because of a meeting of the minds. If either party or both parties do not understand any term in the contract, there is no consensus ad idem.

To put in place a blanket rule that would make contracts in this situation unenforceable could be problematic. A common law has evolved to prevent abuse of legal provisions and created rules dealing with mistakes. One type of mistake involves a party that is mistaken in the kind of contract to be signed.

An example would be someone signing away the deed to their home thinking the document they signed was simply a guarantee for a debt held by another person or they were witnessing a will. In this situation, the person signed the document under the mistaken impression of what the document was for. This would be an instance where non est factum would be used as a defense to avoid the contract.

Because of the complexity of non est factum, a case by case resolution is more advantageous than applying a generic rule or principle when governing the cases. In cases where non est factum is the plea, the aim is to strike a balance between the needs of the person who signed the document and whose consent is not valid and protecting any third party who may be innocent, having only acted on what they thought was a properly executed agreement.

Example of Non Est Factum

When using non est factum as a defense, its application is restricted to certain circumstances. The person using non est factum must show two things: that they were not careless and that the document they initially signed was not the same document they thought they were signing. 

The use of non est factum as a defense is prevalent among defendants who are intent on evading a contract because it renders a signed contract/agreement void and, therefore, unenforceable. This mode of defense has strict requirements, which requires the defense to confine its cases to those defendants who were unable to read the agreement. This could be due to illiteracy, although illiteracy on its own may not be enough. 

An example of illiteracy not being enough to void a contract involves a realtor and a real estate developer. The realtor wanted several agreements voided because his defense was he did not understand real estate development well enough nor did he know English. Thus, non est factum was considered as the defense. In this case, the defendant had the burden of proving his defense based on the requirements that must be met when using non est factum as a defense. 

At trial, it was shown through testimony that the realtor was, in fact, an experienced business person and capable of understanding documents and agreements written in English. He had also been advised to seek legal counsel before signing the agreements. The court found the realtor's claim that he would have no problem with signing a document that he had not read or did not understand to be unbelievable and ultimately held that the defense had not made a case for non est factum. The signed agreements remained binding.

This case showed that non est factum as a defense should only be used in special circumstances and that winning such a case rarely happens.

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