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The “reasonably diligent search” in Canadian obviousness analysis

Source: Jennifer Ponton & Christine Genge - Smart & Biggar


Can a book on a dark and dusty shelf in a public library render a patent obvious? In the recent decision of E Mishan & Sons Inc v Supertek Canada Inc, 2015 FCA 163, the Federal Court of Appeal noted that none of the parties made any submissions regarding whether the codification of the test for obviousness changed the test for determining what documents would be included as part of the relevant prior art. Absent any such submissions, the Court of Appeal applied the “reasonably diligent search” test.


Prior to the 1996 amendments to the Patent Act there was no explicit requirement of non-obviousness in the Patent Act. Instead, the concept of non-obviousness was implicit in the definition of invention under section 2. In defining the requirement, the courts established that, to be citable for the purposes of obviousness, the reference had to be findable through a “reasonably diligent search”.

Non-obviousness is now explicitly codified in section 28.3 of the Patent Act. This section states that prior art must be “available to the public” to be citable. In the leading case on obviousness in Canada, Apotex Inc v Sanofi-Synthelabo Canada Inc, 2008 SCC 61, the Supreme Court set forth a four-part test, part three of which involves identifying the differences between the inventive concept of the claim and the “state of the art”. The question, then, is whether the “state of the art” for the purposes of the obviousness analysis includes any information that became “available to the public” or, is limited by a “reasonably diligent search”.

The Mishan v Supertek decision

E Mishan & Sons, Inc v Supertek Canada Inc was an appeal from a decision of the Federal Court that found certain claims of Canadian Patent No. 2,779,882 (the ‘882 Patent) invalid for obviousness. The ‘882 Patent related to an expandable and contractible garden hose. The Appellants submitted that the trial judge erred by including the McDonald Patent as part of the relevant prior art.

The Appellants argued that the McDonald Patent was not prior art forming the state of the art because the test for determining what documents are to be included as part of the relevant prior art is not based on whether a particular document is “findable.” According to the Appellants, simply because the Respondents’ lawyer found the McDonald Patent does not mean that it would have been found by the Skilled Person.

The Court of Appeal acknowledged the test set out in Apotex Inc v Sanofi-Aventis, 2011 FC 1486, where it was stated that “…the prior art must have been publicly available as of the [relevant] date… – and it must further have been locatable through a reasonably diligent search”. The Court of Appeal noted that none of the parties in the appeal made submissions in relation to whether section 28.3 of the Patent Act changed the test for determining what documents would be included as part of the relevant prior art. The Court of Appeal indicated that presumably any submissions would be that the scope of documents would include any information that became “available to the public” and not just restricted to documents that could be found by conducting a “reasonably diligent search.” As such, the Court applied the “reasonably diligent search” test.

The Court of Appeal concluded that the trial judge did not err by holding that the McDonald Patent would have been found in a “reasonably diligent search” and therefore constitutes part of the state of the art. The Court of Appeal also held that it is a finding of fact or mixed fact and law whether the Skilled Person would have located the prior art through a “reasonably diligent search”. Thus, this finding would stand absent a palpable and overriding error.

Other recent case law has also continued to apply the “reasonably diligent search” test. For example, in Eurocopter v Bell Helicopter Textron Canada Limitée,2012 FC 113, aff’d 2013 FCA 219, the Court noted that it was entitled to look at all the patents and other publications that a skilled technician would discover in a ‘reasonable and diligent search’ to determine whether the resulting mosaic leads directly to the invention. Similarly, in Takeda Canada Inc v Canada (Minister of Health), 2015 FC 570, the Court accepted the opinion of the experts who confirmed that the art cited in Apotex’s Notice of Allegation would have been located on a “reasonably diligent search”.


For now, it appears that the “reasonably diligent search” test is still applicable in Canada. That is, when considering prior art put forth by the parties for the purposes of the obviousness analysis, the courts will consider whether the reference would have been found through a “reasonably diligent search”.


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Author: grill-ip

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