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Admissibility of Foreign Prosecution History in Canada

Mar 17 2021

On January 20, 2021, the Federal Court of Appeal (FCA) issued its much anticipated decision in CanMar Foods Ltd. v. TA Foods Ltd, 2021 FCA 7 [Canmar FCA]. In dismissing Canmar’s appeal of the earlier Federal Court (FC) decision by Justice Manson (2019 FC 1233), the FCA provided clarification on the scope of the recently introduced Section 53.1 of the Patent Act. Specifically, the Court addressed the admissibility of foreign prosecution history for the purposes of claim construction in a patent infringement trial.

Prior to legislative amendment in 2018, the notion of file wrapper estoppel was firmly rejected by the Supreme Court of Canada in the seminal case Free World Trust v Électro-Santé Inc, [2000] 2 SCR 1024 [Free World Trust]. Then Justice Binnie opined that extrinsic evidence such as statements or admissions made in the course of patent prosecution ought not to be allowed for the purpose of construing the claims as they would “undermine the public notice function of the claims, and increase uncertainty as well as fueling the already overheated engines of patent litigation".1 In late 2018, through the omnibus Budget Implementation Act, Section 53.1 was introduced into the Patent Act, formally recognizing file wrapper estoppel in Canadian patent law.   

Canmar Foods Ltd v TA Foods Ltd, 2019 FC 1233 [Canmar FC] was the first case to test the scope of admissibility under the new S. 53.1. The patentee had acknowledged during prosecution that the Canadian claims were amended to substantially reflect their U.S. counterparts. On this basis, the defendant asked the court to consider the U.S. file wrapper in its claim construction. Justice Manson agreed that the file wrapper of the corresponding U.S. application may be considered under S. 53.1. In so doing, the judge introduced the concept of “extraordinary circumstances” under which foreign file wrappers may be admissible as part of the Canadian prosecution file history under S.53.1.2 It was deemed that such circumstances arose in the case where the patentee referenced the foreign prosecution history, and the patentee acknowledged that the relevant claim amendments were made in order to overcome prior art.3 Justice Manson went on to justify that consideration of a foreign file wrapper was warranted in this case as ignoring the reference to the United States prosecution history “would emasculate the intent and effect of section 53.1”.Having reviewed the U.S. file wrapper, the judge concluded that the claim elements at issue were essential and not infringed by the defendant.

On January 20, 2021, the Canmar FCA decision was issued. Although the FCA upheld the lower court's dismissal of the patent infringement action, the Court of Appeal was of the opinion that Justice Manson erred in law by considering the U.S. file wrapper in this case. With a review of both U.S. and U.K. precedents, the FCA reaffirmed the notion that the communications made during prosecution of a patent are only permissible for the limited purpose of rebutting a representation made by the patentee as to the construction of a claim in that patent, and not an independent, stand-alone aid to claim construction.5 Further, the Court opined that S. 53.1 is specifically limited to communications made between the patentee and the Canadian Patent Office, and cautioned that any attempt to extend the language of the section would go against statutory interpretation principles by going beyond the original intent.6 The Appellate court also put forth a public policy reason for limiting the scope of S. 53.1 as a more expansive reading of the section that leads to allowance of additional extrinsic evidence may lead to overly contentious and expensive litigation.7

Regarding the case at bar, the Appellate Court is of the view that a mere mentioning of “a related United States application” by the patentee is an insufficient ground to invite a review of the foreign prosecution history, and that Justice Manson should not have taken the US file wrapper into consideration.8 Of interest, in distinguishing the United States Court of Appeals (Federal Circuit) case Abbott Labs v. Sandoz, 566 F.3d 1282 (2009) [Abbott Labs] relied upon by Justice Manson, the FCA stated that the US patent in Abbott Labs claimed priority from the application of a foreign patent, which necessarily entails an express reference to a foreign patent.9 The Canmar Patent No. 2,582,376 was a Canadian national phase entry from PCT Application No. PCT/CA2005/001431. The PCT application claims priority from U.S. Provisional Application 60/614,458, which was formalized into U.S. Application No. 11/576,405 that was later abandoned. Hence, a priority claim may constitute an explicit reference to foreign prosecution file history. The Court’s remarks appear to suggest that a more specific reference to a corresponding application or a more substantial reliance on a particular communication in foreign prosecution history may have be sufficient to invoke S.53.1. Thus, it may be prudent for patentees to exercise caution and avoid making such statements to the Patent Office during prosecution of an application.

This article is for information purposes only and does not constitute legal or professional advice.

Author: Steven Cheng


1 Free World Trust, para [66].

2 Canmar FC, at para 73.

3 Canmar FC, at para 74.

4 Canmar FC, at para 71.

5 Canmar FCA, at para 64.

6 Canmar FCA, at para 70.

7 Canmar FCA, at para 71.

8 Canmar FCA, at para 77.

9 Canmar FCA, at para 76.

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Tags: Patents, Steven Cheng