A Word of Caution: File Wrapper Contents Can Come Back to Haunt You


By Jessica R. Sudbury and Claire Palmer, February 6th, 2017

The Federal Court made a sweeping statement in Justice Locke’s decision released last Friday that submissions made to the Canadian Intellectual Property Office (CIPO) during patent prosecution can re-emerge to haunt litigants and hit them where it hurts: the wallet.

On January 27, 2017, the Federal Court released a new decision for the Pollard Banknote Limited v BABN Technologies Corp[1] matter. Pollard Banknote Ltd., the successful plaintiff from last summer’s patent impeachment trial, was awarded costs elevated by 50% above the usual rate for allowable counsel fees and disbursements under the Federal Courts Rules.[2] Several issues concerning conduct of the defence throughout trial grounded the elevated costs award in the judgment,[3] and Justice Locke specifically denounced the fact that the defendant reversed the previous stance taken on claims construction during prosecution of the patent at issue. Justice Locke noted that “based on jurisprudence that is clearly binding on me, I ignored the position that SG took during prosecution. Instead, I adopted the claim construction position that SG argued at trial. But I observed that it was “breathtaking” to see SG take this position on claim construction without addressing the fact that it reintroduced the problem of obviousness that it had overcome during prosecution by asserting the contrary claim construction position.”[4]

Therefore, patent litigants be forewarned: this latest decision, in combination with the reasons penned by Justice Locke following last summer’s patent impeachment trial, makes it clear that file wrapper contents are not laid to rest in Canada once a patent application goes to grant. This point was also highlighted in last summer’s Federal Court judgment that, in one fell swoop, invalidated the patent at issue and breathed new life into the long-dead issue of patent file wrapper estoppel doctrine applicability in Canada.

The doctrine of patent prosecution history estoppel (commonly known as “file wrapper estoppel”) is in full force in the U.S., where it enables courts engaging in claims construction to consider representations made by inventors to the Patent Office during the patent prosecution process. Because inventors before U.S. courts can become “tied” to previous assertions made to the Patent Office concerning the scope of the monopoly claimed, some argue that operation of the doctrine helps conserve valuable resources by abridging or avoiding drawn-out patent disputes and forcing inventors to carry out more due diligence checks prior to commencing proceedings.

Unlike its U.S. counterpart, the Supreme Court of Canada (SCC) has historically held that representations made during the patent prosecution process constitute extrinsic and inadmissible evidence for claims construction during patent litigation.[5] Judges here are thus expected to interpret claims through a purposive construction lens that ignores all statements from the inventor contained within the patent file wrapper that might otherwise help resolve a drafting ambiguity. The Federal Court’s pronouncements on the Pollard v Babn matter make it clear, however, that inventors and IP practitioners are no longer completely unconstrained to make whatever admissions are necessary to overcome objections by CIPO examiners.

In Justice Locke’s July 28, 2016 reasons, he openly beckoned for a reconsideration of the SCC’s position on the file wrapper estoppel doctrine, noting that “prosecution histories in many jurisdictions (including Canada) are now available on the internet. This raises the question whether it is time to revisit the rule against using extrinsic evidence in claim construction.”[6] In other words, once these documents are placed into the public domain, why then restrict reliance on their contents?

The Court in the Pollard v Babn matter was confronted with a difficult situation because i) the application prosecution history was admitted on grounds other than for the purpose of construing the patent claims, and ii) these documents revealed that the inventor had taken a completely opposite position toward the meaning of a claim as worded during the prosecution process. Justice Locke repeatedly stated that the prosecution history evidence did not bear on his finding that the impugned claim was invalid for obviousness. However, in obiter, Justice Locke noted that “it is breathtaking to see SG now attempt not just to take a different position on the construction of claim 1, but also to argue that, by doing so, it does not reintroduce the problem of obviousness in light of the Camarato Application that it had previously argued was avoided applying its first position.”[7]

Counsel for the Defendants filed a Notice of Appeal at the Federal Court on September 29, 2016 against Justice Locke’s July 28, 2016 decision.

In the wake of the Pollard v Babn matter and pending determination on any related appeals, inventors and IP practitioners would be well-advised to adjust their practices accordingly, bearing the following points in mind:

i) File wrapper estoppel doctrine may yet become revived in Canada. The outcome of appeals related to the Pollard v Babn matter should be carefully monitored.

ii) Even if prosecution history evidence remains buried under Canadian patent law for claim construction purposes, all litigants remain vulnerable to the fact that cases are heard by human beings. Presiding judges nevertheless can become privy to file wrapper contents if admitted for a different stated purpose,[8] and the hearing of such evidence can bear an influence on all determinations made for the same matter.

iii) Litigants are well-advised to meticulously review file wrapper contents prior to commencing proceedings, or risk facing elevated costs awards on the basis of flip-flopped arguments.

For more information please contact:

Jessica R. Sudbury, Articling Student

T: 613.801.0762

E: This e-mail address is being protected from spambots. You need JavaScript enabled to view it.


Claire Palmer, Senior Patent Agent

T: 613.801.0450

E: This e-mail address is being protected from spambots. You need JavaScript enabled to view it.

[1]Pollard Banknote Limited v BABN Technologies Corp, 2016 FC 1193 (Pollard v Babn 2).

[2]Federal Courts Rules, SOR/98-106 at RR 400 & 407.

[3]Pollard v Babn 2 at para 36.

[4]Pollard v Babn 2 at para 31.

[5] See, for example, Free World Trust v Électro Santé Inc, 2000 SCC 66 at para 66.

[6]Pollard v Babn 1 at para 80.

[7]Pollard v Babn 1 at para 237.

[8] For example, where a party is compelled to produce file wrapper documents during an examination for discovery (e.g., Foseco Trading v Canadian Ferro Hot Metal, 1991 FCJ 421), or to establish an essential element of an impugned patent (e.g., Distrimedic Inc v Dispill Inc, 2013 FC 1043).
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