The Supreme Court of Canada has dismissed an appeal by Apotex Inc. and upheld an order of prohibition granted in respect of the drug PLAVIX (clopidrogel bisulphate). Sanofi-Synthelabo Canada Inc. and Sanofi-Synthelabo were represented by Gowling Lafleur Henderson LLP (Anthony Creber, Cristin Wagner, Jay Zakaib).

The unanimous decision of the Supreme Court of Canada, authored by Justice Rothstein, is significant in that the Court clearly upheld the doctrine of selection patents, which encourages innovation through improvement. Selection patents have particular importance in the field of medicinal chemistry, although, as noted by the Court, the doctrine of selection patents is of general applicability in patent law. The Court held that a selection patent that claims subject matter that is patentably distinct from a genus patent will not be invalid for obviousness type double patenting. However, the specification of the selection patent must clearly define the advantage possessed by the selection. In this case, the particular advantage identified in the patent specification was that the dextro-rotatory isomer of clopidrogel was less toxic and better tolerated than the levo-rotatory isomer and the racemate. The specific advantage of this selection had not been identified in the genus patent or otherwise in the prior art.

The decision was also noteworthy in that the Court "refined" the established tests for anticipation and obviousness as set out by the Federal Court of Appeal in Beloit Canada Ltd. v. Valmet OY. In doing so, the Court relied heavily on jurisprudence from the UK. The Court's findings take an approach with respect to obviousness and anticipation which is in closer proximity to the tests set out in the UK jurisprudence.

With respect to an allegation of anticipation, the Court held that a two-step analysis is to be undertaken where the requirements of "prior disclosure" and "enablement" are to be separately examined and demonstrated. In the context of selection patents, in order to have prior disclosure the Court found that the genus patent must disclose the special advantages of the selection patent. For "enablement" to occur, the genus patent must provide sufficient information to allow a person skilled in the art to perform or make a subsequently claimed invention without "undue burden". For the purposes of enablement, in addition to using the common general knowledge and prior art at the relevant time , the person skilled in the art may conduct routine trials or experimentation to supplement the information in genus patent. The Court found that, in this case, the allegation that the patent was invalid on the basis on anticipation was not justified. The specific advantages of the more active isomer were not disclosed in the genus patent and the evidence indicated that considerable effort was required in the form of extensive investigations to obtain the invention of the species patent.

The Supreme Court also recalibrated the test for obviousness and indicated that a less rigid application of the standard set out in Beloit was appropriate. Most significantly, the Court commented on the circumstances in which a consideration of whether an invention was "obvious to try" would be warranted. The Court held that to found an assertion that an invention was "obvious to try", an obviousness indicator applied by the UK courts but previously not applied in Canada, there must be evidence to convince a judge on a balance of probabilities that it was "more or less self-evident" to try to obtain the invention. A mere possibility that something may turn up is not enough. The Court also cautioned that whether the invention was "obvious to try" is only one factor to assist in the obviousness inquiry and will not be appropriate in all circumstances. In this instance, the Court found that the invention was not self-evident from the prior art and the common general knowledge. The Court noted that the beneficial properties of the dextro-rotatory isomer had not previously been disclosed and thus the advantage was not quickly or easily predictable. The Court also recognized the extensive work done by the patentee in developing the invention as an indicator of non-obviousness.

Therefore, the Court held that Apotex' allegation of invalidity was not justified and upheld the order prohibiting the Minister of Health from granting regulatory approval to Apotex to market a generic copy PLAVIX. The Federal Court of Appeal had dismissed a previous appeal from the decision of the Federal Court granting the prohibition order.

To review the Supreme Court decision, Apotex Inc. v. Sanofi-Synthelabo Canada Inc. et al., 2008 SCC 61, please see: