1 May 2010AmericasKatie Wang

Stricter examination requirements in Canada

Duty of candour

A recent case from the Federal Court in Canada has highlighted the importance of duty of candour during prosecution and closely scrutinising the file wrapper in assessing patent validity.

The duty of candour is a well-established doctrine in the United States. It requires every party to a patent application, including a patent applicant and its agents, to disclose to the United States Patent and Trademarks Office all publications that they know of that may adversely affect the patentability of their invention.

In contrast, in the past, Canada had put a much less onerous burden on the applicants and their patent agents. It was generally understood that the duty of candour was limited to an obligation to “reply in good faith to any requisition made by an examiner”.

However, recent cases from the Federal Court of Canada appear to have shifted the traditional approach. The court has emphasised the importance of duty of candour and even accepted grounds for attacking validity of patents on the basis that submissions by the applicant during patent examination were not made in good faith.

In the recent case of Lundbeck Canada Inc. v. Ratiopharm Inc, the Federal Court of Canada held that the duty of good faith requires that prior art be fully and fairly described by the applicants and their agents when responding to requisitions from the Canadian Patent Office. In Lundbeck, a patent was held invalid for failure to respond in good faith to an examiner’s requisition.

The patent in this case claimed a combination of two drugs. During examination of the patent application, the examiner requisitioned the applicant to identify the prior art cited in corresponding foreign applications. The applicant responded by identifying two prior art documents cited in the International Search Report, one of which was a prior art reference referred to as the Wenk article. The response from the applicant did not include a discussion of the Wenk article.

During further prosecution, the Canadian examiner noted that separate use of these drugs was known and, as such, rejected the claimed combination based on the ground of obviousness. In response to the examiner’s requisition, the applicant referred to four prior art references in which similar combinations had reduced the effectiveness of one of the drugs and stated that the prior art clearly “taught away” from the claimed combination. The applicant, however, did not mention the Wenk article, which stated that some combinations were effective while others were not.

The court was of the view that the Wenk article speculated the use of the claimed combination and so was more relevant than any of the four references referred to by the applicant in its response. Furthermore, the court held that the statement made by the applicant during prosecution that the prior art clearly taught away from the combination was not a fair representation of the teachings of the prior art. The court therefore concluded that the applicant had failed to reply in good faith to the examiner’s requisition.

This finding is significant. Pursuant to Section 73 of Canada’s Patent Act, it is stipulated that an “application for a patent in Canada shall be deemed to be abandoned if the applicant does not…reply in good faith to any requisition made by an examiner in connection with an examination”.

The court in Lundbeck referenced this section of the Patent Act, as well as a previous Federal Court decision in G.D. Searle & Co. v. Novopharm Limited. In the Searle decision, a patent was considered invalid based on the fact that the applicant presented arguments during prosecution that were inconsistent with an article that had been published by the applicant and this was not brought to the attention of the examiner.

The Searle decision was overturned on appeal on other technical arguments and the court in Lundbeck considered the Searle decision to present an accurate overview of the obligations of the applicant during prosecution. It quoted the following from the Searle decision:

“[C]ommunications with the examiner must be made in good faith. It is to be expected that there will be full, frank and fair disclosure. There is afforded during the prosecution ample opportunity to make further disclosure or to correct an earlier misstatement or shortcoming. It is 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.”

The court in Lundbeck followed the Searle decision and held that this duty was not met in the Lundbeck case, and therefore, the patent application was deemed abandoned and the patent was dead.

It further held that the duty of candour during prosecution of a patent application is akin to an ex parte court proceeding wherein a party “must state his or her own case fairly and must inform the court of any points of fact or law known to it which favour the other side”.

The Lundbeck decision is significant in that the duty of candour owed by patent applicants in Canada has gone from almost non-existent to a high standard analogous to ex parte proceedings. As a consequence, applicants and their patent agents should take extreme care in responding to Canadian examiners’ requisitions.

Applicants must avoid mischaracterising prior art references and making broad and general statements of the teachings of the prior art. The applicants must take care to not mislead the examiner, even unintentionally.

At the same time, for parties intending to invalidate patents, file wrappers should be scrutinised carefully to ensure that the patentee has complied with the duty of good faith during patent prosecution.

Claim construction

The recent case of Janssen-Ortho Inc. v. Novopharm Limited, brought under the Patented Medicines (Notice of Compliance) Regulations, concerns Janssen-Ortho’s Canadian Patent No. 2,264,852 (the ‘852 patent). The crux of the case lies in the interpretation of the term “in a sustained-ascending dose” in each of the three independent claims of the ‘852 patent and whether the Novopharm product would infringe these claims.

The claims refer to the “use of composition […], the composition releasing methylphenidate in a sustained-ascending dose over time […]”. Janssen-Ortho asserted that the term referred to a methylphenidate plasma concentration profile, while Novopharm alleged it referred to the release rate of methylphenidate from the dosage form.

The court, after a lengthy discussion on the principles of claims construction, held that one ought first to look at the dependent claims as an aid to interpreting the independent claims, before resorting to the disclosure. It held that by considering the disclosure before considering the dependent claims, one runs a risk of forming an opinion as to the proper construction of the independent claims based on the content of the disclosure, when that interpretation is not supported or may even be contrary to the dependent claims.

The court found that the dependent claims in the ‘852 patent clearly used the term “dose” in reference to an “amount” of methylphenidate contained in the dosage form and determined that this initial interpretation of the claims was confirmed by the disclosure of the ‘852 patent. The court further held that Novopharm’s product releases methylphenidate from its dosage form in a manner other than a sustained-ascending dose over time and therefore would not infringe the claims of the ‘852 patent.


The Janssen and Lundbeck cases provide helpful guidance on patent claim construction and patent prosecution in Canada. While claim construction normally involves a hierarchical process that starts with the claims and ends with the disclosure, it is a good idea to maintain consistency throughout the entire specification of a patent. In addition, patent practitioners should be mindful of the continuing development of the scope of duty of candour during prosecution.

Katie Wang is a lawyer and patent and trademark agent at Shapiro Cohen. She can be contacted at: kwang@shapirocohen.com

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