Non est factum

Justice Cartwright described non est factum in Marvco Colour Research Ltd. v. Harris [1982] 2 SCR 774:

"(W)here a document was executed as a result of a misrepresentation as to its nature and character and not merely its contents the defendant was entitled to raise the plea of non est factum on the basis that his mind at the time of the execution of the document did not follow his hand."