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Signature Upon Document:
Establishes Contract Relations Unless the Signature Was Obtained Improperly
Last Updated: August 22 2026
Question: In Ontario, when is a signed contract enforceable and when can it be challenged due to misrepresentation, duress, undue influence, or lack of real intention?
Answer: Mole Legal Services can help you in Ontario assess whether your signed agreement is likely enforceable or vulnerable due to issues like misrepresentation, duress by threats, undue influence, or non est factum arguments where a court finds there was no genuine intention to agree. Enforceability is generally presumed for properly formed contracts, but a contract may be treated as a nullity if improper conduct caused the signature, and courts often limit non est factum where the signer was careless in not reading the document; for example, the court in Alphera Financial Services Canada (BMW Canada Inc.) v. Ambihaipalan, 2021 ONSC 3530 discusses that the defence requires misrepresentation and lack of carelessness. If you’re dealing with a dispute over contract obligations in Brampton, Oakville, Milton, Toronto, Ajax or nearby, call (647) 709-5157 for a quick paralegal and property-management aware review of your facts and next steps.
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Principles of Signed Contracts Including Enforceability Concerns
To enable confidence and security in the day-to-day function of business and commerce, assurance in the enforceability of contracts is of strong importance and is a need well recognized within the law. Generally, the law will treat most contracts as genuinely entered into by the parties and will therefore enforce the contract subject to a few rare exceptions.
Note: Please contact Mole Legal Services by phone at: (647) 709-5157 to discuss any specific questions that you may have.
The Law
Where it is shown that a contract was entered into without a genuine intention, due to some form of improper conduct such as undue influence, duress by threat, misrepresentation, or lack of genuine bargaining, a court may deem that a contract is without binding force and is therefore merely just the appearance of a contract.
Intention
A contract, even if involving a signed document, legally exists only where a court may deem that the parties to the purported contract was entered into with intention. Whereas a person was misled by false information, or other improper conduct, and would have declined to enter into the contract if the truth was told, a binding contract fails to exist. Simply said, whereas a court determines that a person agreed to a contract only because of information or documents presented by the other person, or persons, to the contract, the court will deem that a lack of genuine willingness to agree occurred. In law, the appearance of an intention that is instead legally deemed as a lack of intention, is often referred to by the Latin phrase non est factum, loosely meaning not his act or not his deed; and accordingly, the non est factum issue arises in law when a person argues that improper conduct, essentially some trick of sorts, was used to cause a person to unwittingly enter into a contract. In regards to non est factum, this was explained well in the case of Alphera Financial Services Canada (BMW Canada Inc.) v. Ambihaipalan, 2021 ONSC 3530 which stated:
[32] The defence of non est factum is available to “someone who, as a result of misrepresentation, has signed a document mistaken as to its nature and character and who has not been careless in doing so.”: Marvco Color Research Ltd. v. Harris, 1982 CanLII 63 (SCC), [1982], 2 S.C.R. 774, and Bulut v. Carter, 2014 ONCA 424.
[33] The absence of a misrepresentation and carelessness are fatal to the defence: The Guarantee Company of North America v. Ciro Excavating & Grading Ltd., 2016 ONCA 125 (CanLII). See Dorsch v. Freeholders Oil Co. Ltd., 1965 CanLII 90 (SCC), [1965] S.C.R. 670. This approach is based not only upon the principle of placing the loss on the person guilty of carelessness, but also upon a recognition of the need for certainty and security in commerce. Waberley v. Cockerel (1542), 1 Dy. 51.
[34] In Muskham Finance Ltd. v. Howard, supra, at p. 912, Donovan L.J. stated:
Much confusion and uncertainty would result in the field of contract and elsewhere if a man were permitted to try to disown his signature simply by asserting that he did not understand that which he had signed..
As was further explained in Alphera Financial at paragraphs 35 to 38, the carelessness of a person who signs a contract without reading the contract fails to legally excuse a person from the obligations of the contract. On this point, the Supreme Court in the case of Marvco Colour Research Ltd. v. Harris, [1982] 2 SCR 774, which was cited in Alphera Financial, said:
... As between an innocent party (the appellant) and the respondents, the law must take into account the fact that the appellant was completely innocent of any negligence, carelessness or wrongdoing, whereas the respondents by their careless conduct have made it possible for the wrongdoers to inflict a loss. As between the appellant and the respondents, simple justice requires that the party, who by the application of reasonable care was in a position to avoid a loss to any of the parties, should bear any loss that results when the only alternative available to the courts would be to place the loss upon the innocent appellant. ...
Of course, this is without saying that any contract signed is enforceable. The key point in Marvco Colour is that where a party carelessly signs a contract and the other party is innocent of any wrongdoing, the careless party is inexcused from the contract; however, if there was wrongdoing, such as deceit, misrepresentation, undue influence, or duress, that unduly contributed to the signing of the contract, then regardless of the carelessness, the contract should be deemed a nullity.
Conclusion
Generally, a signed contract is enforceable unless it is shown that the party who signed the contract only did so due to some wrongdoing on the part of the other party to the contract such as deceit, misrepresentation, undue influence, duress, or concealment of unusual and unexpected onerous terms.
NOTE: A considerable amount of online searches featuring “lawyers nearby” or “top lawyer in” frequently indicate a desire for prompt and competent legal assistance rather than a particular professional designation. In Ontario, licensed paralegals are governed by the same Law Society responsible for lawyers and are permitted to represent clients in certain legal matters. Key aspects of this role include advocacy, legal analysis, and procedural expertise. Mole Legal Services provides legal representation within its licensed parameters, focusing on strategic approaches, evidence preparation, and effective advocacy to secure timely and advantageous outcomes for clients.
