Which statement describes the doctrine of non est factum as it applies to contracts?

The doctrine of non est factum, literally meaning “it is not my deed,” may provide relief where a person signs a document while fundamentally mistaken about the nature or legal character of the document being executed. Accordingly, option B captures the essential contractual principle.

The doctrine is narrower than ordinary mistake or misrepresentation. It is not enough that a party misunderstood a particular contractual term, underestimated the financial consequences, or later regretted signing. The error must concern the document's essential nature or effect. Canadian jurisprudence also imposes an important diligence requirement: a person who carelessly signs a document without taking reasonable steps to understand it may be prevented from relying on non est factum, particularly where an innocent third party relied on the signed instrument. The Supreme Court of Canada applied this principle in Marvco Colour Research Ltd. v. Harris.

Option A describes misrepresentation. Option D describes common mistake, where both parties share a fundamental erroneous assumption. Option C may involve mistake concerning the existence of subject matter or impossibility, not non est factum.

FPII reference/topic: Financial Planning Practice — contract law; validity and enforceability of contracts; mistake; misrepresentation; non est factum.

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