What is the test for adduced to vary or contradict a document?

Justice Swinton, in Deonarine v. Lachman, 2004 CarswellONnt 850, [2004] O.J.No. 823, states that “There are, however, exceptions to the parol evidence rule. Such evidence may be adduced to vary or contradict a document if the evidence shows that a contract is invalid because of …lack of consideration…” Since the purpose of the oral evidence in this case is to show that the contract is invalid for lack of consideration, it fits squarely within this exception to the parol evidence rule.

Finally, Jason’s evidence goes to the issue of performance, not construction. His evidence is not intended to alter the terms of the agreement; rather, it is evidence of whether he actually received the consideration that was promised. While this may be said to “contradict” the term that acknowledges receipt of the ten dollars, that is not the same as using oral evidence to alter unambiguous terms or show the existence of a collateral or supplementary agreement, which is the purpose of the parol evidence rule (Hawrish v. Bank of Montreal, 1969 CanLII 2 (SCC), [1969] SCR 515).