In recent years, Canada’s Federal Court has generated much debate with respect to whether patent applicants in Canada owe a “duty of candour” during prosecution of patent applications, especially under section 73 of Canada’s Patent Act.  Canada’s Federal Court of Appeal has now issued a decision dated July 18, 2011 that conclusively states that section 73(1)(a) cannot be relied upon to attack the validity of a patent after it has issued.

This issue was presented in Weatherford Canada Ltd. v. Corlac Inc. (Weatherford) (2011 FCA 228), which also involved an intervention by the Intellectual Property Institute of Canada.  In Weatherford, the appellants argued that the patentee had not complied with the provisions of section 73(1)(a) of the Patent Act during prosecution of the application and therefore, the patent application had been abandoned.  This section states, inter alia, that an application for a patent shall be deemed to be abandoned if the applicant does not reply in good faith to any requisition made by an examiner within the prescribed time period.  The appellants argued that non-compliance with section 73 is sufficient for the abandonment of a patent, both during prosecution and post-issuance.

After conducting an analysis of section 73, including its legislative history, the Court of Appeal emphasized that the concept of abandonment under section 73(1)(a) operates during the prosecution of the application for a patent, and its operation is extinguished once the patent issues.  If there is an allegation of misrepresentation post-issuance, then section 53(1) of the Patent Act applies, which has been the long-standing provision regarding misrepresentations.  Section 73(1)(a) cannot be relied upon post-issuance to challenge the validity of a patent since it would allow an issued patent to be subject to retroactive scrutiny by the courts in relation to submissions made by a patent applicant to the Patent Office during prosecution.  It is for the Commissioner of Patents and not the courts to determine if those submissions were made in good faith in response to a requisition from an examiner.

In two previous decisions, the state of law in Canada had been left with some uncertainty since they raised the concept of whether there was a duty of candour during prosecution of patent applications.  In the 2009 decision of Lundbeck Canada Inc. v. Ratiopharm Inc. (“Lundbeck”) (2009 FC 1102), the Federal Court addressed section 73(1)(a) in an analysis of whether this provision gives rise to a duty of candour during prosecution of patent applications.  The Court noted that section 73(1)(a) explicitly imposes a duty to reply in good faith to a requisition, and at this point, there is a duty of candour on the part of applicants in the prosecution of a patent application.  The Court cited with approval earlier comments in G.D. Searle & Co. v. Novopharm Ltd. (“Searle”) (2007 FC 81), wherein the Court concluded that communications with an examiner must be made in good faith.  The Court in Searle also held that it was “not harsh or unreasonable, if after the patent issues, and disclosure is found to lack good faith, that the Court deems the application and thus the patent, to have been abandoned.”

In Weatherford, the Court of Appeal has now established its position on this point by concluding its analysis with the following reference to these cases:

To the extent that the Federal Court decisions in G.D. Searle and Lundbeck can be interpreted as standing for the proposition that paragraph 73(1)(a) can be relied upon for the purpose of attacking the validity of a patent, they should not be followed.

This clarification from Canada’s Federal Court of Appeal is welcome guidance to patent practitioners, as well as patent applicants and owners regarding the scope of section 73.  This decision ensures that an owner of an issued patent should not be subject to a validity attack under section 73(1)(a) based on responses to requisitions from an examiner that occurred during prosecution of the underlying application.