Federal Court of Appeal Restricts Admissibility of Foreign Prosecution History

Federal Court of Appeal Restricts Admissibility of Foreign Prosecution History

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Canmar Foods Ltd. v. TA Foods Ltd., 2021 FCA 7

On January 20, 2021, the Federal Court of Appeal (“FCA”) dismissed CanMar Foods Ltd.’s (“CanMar”) appeal of a decision heard by the Federal Court (“FC”) in 2019. The proceeding was an action for patent infringement brought by CanMar against its fellow Canadian Prairies flax seed competitor, TA Foods Ltd. (“TA Foods”).

Beyond the dismissal, two significant developments can be gleaned from this decision. Firstly, the FCA affirmed the trial judge’s use of summary judgement on substantive grounds, a request the FC has typically been reluctant to grant in patent proceedings. Secondly, the FCA provided a very narrow interpretation of section 53.1 of the Patent Act (“Act”), limiting the use of foreign prosecution history.


The dispute between the corporations arose specifically over CanMar’s patented method of roasting oil seeds. In response to CanMar’s allegations of infringement, TA Foods requested a summary judgement based on non-infringement, which would allow the judge to expedite the trial in order to avoid unnecessary litigation.

Additionally, TA Foods relied on s. 53.1 of the Act, the file wrapper estoppel provision, which permits statements made during prosecution to be admitted into evidence to rebut any representation made by the patentee as to the construction of a claim. The Act was amended to include this provision in December 2018 and had not yet been interpreted.

Notably, the FC opted to resolve the matter by way of summary judgement and without reference to expert evidence. Further, it was held that only under extraordinary circumstances could prosecution histories from foreign jurisdictions be relied upon. Further details of Justice Manson’s judgement can be read here.

In several decisions that followed, the FC has continued on its trend of disposing matters by way of summary judgement or summary trial. For one recent example, see our reporting of Flatwork Technologies v. Susan Brierley.


On appeal, CanMar argued that the trial judge erred in granting summary judgement, as insufficient evidence had been presented relevant to the alleged infringement [25].

CanMar further argued that expert evidence is required in a claim construction analysis and it was an error in law for the FC to construe a patent without this [31].

Lastly, CanMar argued that the trial judge erred in having recourse to the US prosecution history. CanMar suggested that section 53.1 of the Act was not intended to apply to patent construction and even if it was, it was not applicable to communications from foreign jurisdictions [64].

On Granting Summary Judgement

The FCA began its address with a recognition of the purpose of summary judgement motions, describing them as an “important tool for enhancing access to justice” that “must be interpreted broadly so as to promote affordable, timely and just adjudication of civil claims” [23].

Responding to the evidentiary concerns, the FCA held that a motion for summary judgement may be brought before discovery takes place and CanMar had all of the information it needed from TA Foods to collect the relevant evidence [26] [28].

On Claim Construction and Expert Evidence

CanMar’s argument was found to be unconvincing and without merit [36]. The FCA did however, caution that “it is only in the clearest of cases” that judges should forego the assistance of expert evidence in construing claims [37].

On the Application of File Wrapper Estoppel

In unwrapping section 53.1, although the FCA made comparisons to equivalent British and American doctrines, it emphasized that an interpretation of prosecution history in Canada will be dependent on the text of the provision [70].

Partially rejecting CanMar’s argument, the FCA confirmed that prosecution history may be admitted to rebut any representation, including matters of claim construction [64]. With respect to foreign prosecution history, the FCA held that the trial judge erred in making reference to CanMar’s US prosecution history. The Court acknowledged that foreign prosecution history can be problematic, owing to differences in foreign patent systems and translation issues, but the FCA chose not to speak further on circumstances where it may be appropriate [71] [74].

Ultimately, the FC decision was upheld and TA Food’s process for roasting oil seeds was found not to infringe CanMar’s patent. The action was dismissed entirely.


This decision demonstrates that despite the often-complex nature of patent litigation, circumstances may arise where it is appropriate to dispose of meritless actions by way of summary judgement. The once hesitant attitude by the judiciary in honouring these requests appears to be changing.

As for foreign prosecution history, the FCA warned that admitting foreign file wrappers may go beyond the legislative intent of section 53.1, but that is “a question best left for another day” [74]. Though the Court was unwilling to say whether the doctrine of incorporation can be applied to foreign file wrappers, it imposed a significant limitation on file wrapper estoppel. The court firmly refused to look to CanMar’s corresponding US application “when the specific application is not even cited within the document” [76]. This logic could lead to irrational outcomes, with patent drafters avoiding file wrapper estoppel by alluding to foreign applications but not specifically naming the application by number.

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