Canada’s Federal Court Questions No File Wrapper Estoppel on Claim Construction

The Supreme Court of Canada in Free World Trust v Électro Santé Inc, 2000 SCC 66 rejected the use of extrinsic documents such as file wrappers (patent prosecution histories) for claim construction, saying that allowing such evidence would undermine the public notice function of the claims and increase uncertainty.  Hence, there is no equivalent of US file wrapper estoppel in Canada.

Recently, in Pollard Banknote Limited v Scientific Games Products (Canada) ULC, 2016 FC 883, Justice Locke of the Federal Court questioned whether it was time to revisit this finding, as file wrappers, like claims, are publicly available and so give public notice of the contents of the prosecution history.  Nevertheless, Justice Locke re-affirmed that, at present, it is settled in Canada that file wrappers are irrelevant to claim construction and therefore, in the present case, the patentee (Scientific Games) was not estopped from presenting a claim construction that contradicted its previous submissions to the Patent Office during prosecution. 

Justice Locke found however that Scientific Games’ Canadian Patent No. 2,752,551, relating to a two-dimensional authentication barcode hidden under a scratch-off area on print instant lottery tickets, was invalid for ambiguity and obviousness; in the alternative, Pollard did not infringe the patent.

With respect to obviousness, Justice Locke held that a patent should not be granted to a skilled person simply making an obvious change to what was known in the art, even if that art would probably not have been located in a diligent search.   He noted that concerns regarding a diligent search may be more relevant where the obviousness allegations combines two references, neither of which is part of the common general knowledge.