Canada v. General Motors of Canada Ltd., 2008 DTC 6381, 2008 FCA 142 -- summary under Evidence

After referring to Eli Lilly and Co. v. Novopharm Ltd., [1998] 2 S.C.R. 129 ("The contractual intent of the parties is to be determined by reference to the words they used in drafting the document, possibly read in light of the surrounding circumstances which were prevalent at the time") and United Brotherhood of Carpenters and Joiners of America, Local 579, v. Bradco Construction Ltd., [1993] 2 S.C.R. 316 ("The general rule prohibiting the use of extrinsic evidence to interpret collective agreements originates from the parol evidence rule in contract law.....It is generally presumed that when parties reduce an agreement to writing they will have included all the necessary terms and circumstances and that the intention of the parties is that the written contract is to be the embodiment of all the terms.....One of the exceptions to the parol evidence rule has always been that where there is ambiguity in the written contract itself, extrinsic evidence may be admitted to clarify the meaning of the ambiguous term"), the Court found that the trial judge erred in admitting extrinsic evidence as to the meaning of a collective agreement that the taxpayer had entered into in the absence of an ambiguity in the words of the agreement. Furthermore, even if there had been an ambiguity, the trial judge erred in admitting evidence as to the subjective intention of the parties, whereas the extrinsic evidence that is admissible in the event of ambiguity is restricted to evidence of the surrounding circumstances prevalent at the time of entering into the agreement.