Canada: Supreme Court Of Canada Redefines Law On Anticipation And Obviousness

Copyright 2008, Blake, Cassels & Graydon LLP

Originally published in Blakes Bulletin on Intellectual Property, November 2008


On November 6, 2008, the Supreme Court released its decision in Apotex Inc. v. Sanofi-Synthelabo Canada Inc. The primary issue before the court was the validity of selection patents. In its decision, the court upheld the validity of such patents and also established new guidelines for assessing anticipation and obviousness of patent claims.

Selection patents are directed to a specific subset or species of a known class or genus. Patents of this sort are common in, but not exclusive to, the chemical and pharmaceutical fields where a particular compound or a related set of compounds (i.e., a species) within a known class (i.e., genus) are found to have certain significant advantages over other members of the class.

Sanofi-Synthelabo Canada Inc. (Sanofi) is the owner of patent number 1,336,777 ('777) and its predecessor, patent number 1,194,875 ('875). The '777 patent is directed to clopidogrel bisulfate, which is an anti-coagulant marketed by Sanofi under the trade name Plavix. The '875 patent discloses a large genus of related compounds, including a racemate comprising clopidogrel bisulfate as well as its levo-rotatory (L) isomer. In the course of its investigation, Sanofi determined that the D isomer – clopidogrel bisulfate – exhibited higher effectiveness and lower toxicity as compared to the L isomer and the racemate, and obtained the '777 patent on this basis.

Apotex sought a Notice of Compliance (NOC) to market a generic version of clopidogrel bisulfate and, in so doing, challenged the validity of the '777 patent on various grounds including anticipation and obviousness based on the prior '875 patent. The lower courts upheld the validity of the '777 patent and Apotex appealed to the Supreme Court.

The Decision

Selection Patents

In its decision, the court first concluded that selection patents are valid in principle. The court went on to set out the following three-part test for establishing the validity of selection patents:

1. The selected members must provide some substantial advantage (or avoid some disadvantage).

2. The whole of the selected members (subject to "a few exceptions here and there") must possess the advantage in question.

3. The selection must be in respect of a quality or a special character peculiar to the selected group.

On the evidence, the court found the '777 patent to meet these criteria. In this regard, the court highlighted the high effectiveness of clopidogrel bisulfate and the reduced toxicity as compared to its L isomer or the known racemate.


Although the conditions for novelty are set forth in the Patent Act, the 1986 Federal Court of Appeal decision in Beloit Canada Ltd. v. Valmet Oy established the so-called "Beloit" test for determining anticipation. This test requires the finding of anticipation to be based on whether a single prior publication provides clear direction to a person skilled in the art to be lead to the claimed invention.

In the present case, the Supreme Court has deemed the Beloit test to be only the first step in an anticipation analysis. Specifically, the court held that anticipation requires two criteria: 1) disclosure and 2) enablement. The court explained that the Beloit test establishes only the first criterion, namely that the prior art reference must provide a disclosure of the claimed invention. However, the second criterion, namely, that of enablement requires that such disclosure must have been sufficient to enable a person skilled in the art to perform or make the claimed invention without "undue burden". In establishing this two-part anticipation test, the court recognized that, with respect to the enablement requirement, some use of "common general knowledge" and a "normal" amount of experimentation may be permissible.

In its decision, the court appears to have raised the threshold for determining anticipation by introducing the enablement requirement.

Nevertheless, after establishing and applying the two-part anticipation test, the court held that neither criterion was met by Apotex and, in the result, found the '777 patent to be novel over the prior '875 patent.


The test for obviousness also stems from the aforementioned Beloit decision, which stated that for a claim to be found obvious, a person skilled in the art and having common general knowledge must have come directly and without difficulty to the invention. In the present decision, the Supreme Court held that the Beloit test for obviousness has been interpreted too restrictively in Canada and that such definition needed to be re-examined in view of recent U.K. and U.S. law. In this analysis, the court referred to the recent KSR decision by the U.S. Supreme Court.

In its decision, the court has established a refined test for obviousness and determined that an obviousness inquiry should comprise the following four steps:

1. Identification of the relevant "person skilled in the art" and the common general knowledge that such person would have.

2. Construction of the claims in question to identify the inventive concept.

3. Identification of the differences between the construed claim and the prior art.

4. Determination of whether such differences would have been obvious to the person skilled in the art or whether they require a degree of inventiveness.

The above criteria are essentially similar to the Beloit test for obviousness. However, the court further clarified that in some instances, such as where an invention was arrived at after experimentation (as in the case in question), the last step may also involve an assessment of whether the invention was "obvious to try". In summary, the court identified at least the following four factors that may, depending on the facts, be considered in determining whether an invention was "obvious to try":

1. Is it more or less self-evident that what is being tried ought to work? That is, are there a finite number of predictable solutions that will be known to persons skilled in the art?

2. What is the nature and amount of effort required to achieve the invention? Would such effort require routine trials or prolonged experimentation?

3. Is there a motive provided in the prior art to find the solution addressed by the patent?

4. What was the course of conduct that was followed in arriving at the invention? That is, was the invention arrived at quickly and easily in view of the prior art and common general knowledge or did it involve a level of effort or knowledge above that of a skilled person?

With regard to obviousness, the court has arguably lowered the threshold by introducing an "obvious to try" test for determining inventive step. This notwithstanding, after analysing the facts and the claims of the '777 in light of the above criteria, the court found that such claims were not obvious in view of the prior '875 patent.


In this decision, the Supreme Court has provided guidance on a number of issues. First, the court has clarified the validity of selection patents by finding that where a selection, or species, is shown to have a "substantial" advantage over a known genus, it would, subject to other tests of validity, constitute patentable subject matter.

Second, the court has provided additional criteria for determining anticipation and obviousness. A new two-part test for anticipation has been proposed wherein a criterion of enablement has been added. The court has also arguably broadened the definition of obviousness by introducing an "obvious to try" criterion. As indicated above, the court has deemed the previous Beloit obviousness test to be to restrictive and has sought to bring the interpretation of obviousness in Canada in line with that of the United Kingdom and the United States.

It remains to be seen how this decision will be applied by the Canadian courts and the Canadian Intellectual Property Office.

The content of this article is intended to provide a general guide to the subject matter. Specialist advice should be sought about your specific circumstances.

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