Supreme Court of Canada takes on selection patents; clarifies the law of anticipation and obviousness for all patents: A win for patentees? – Sanofi v. Apotex, 2008 SCC 61

Apr 06 2009

On November 6, 2008, selection patents were upheld by a unanimous Supreme Court of Canada. A selection patent is based on a selection of chemical compounds (including pharmaceuticals) from an originating (or genus) patent that describes a class of compounds or reactions in general terms. Selection patents are very important to the pharmaceutical and biotech industries and this was the first ruling on such patents by the SCC (see Legal Alert June 2008, Vol. 27 No. 3 “Proper disclosure in pharmaceutical patents a hot topic”). The Court also took the opportunity to align the tests for anticipation and obviousness with US and UK by providing refinements to the classic tests in the Beloit case followed for over 20 years in Canada.


In this case, Sanofi’s originating patent (‘875 Patent) claimed 250,000 compounds useful in inhibiting platelet aggregation including a racemate of clopidrogel. A racemate contains equal amounts of two structurally different compounds called isomers. Sanofi’s later selection patent (‘777 Patent) claims one of these isomers of clopidrogel, (called PLAVIX) since it was found to be less toxic and better tolerated than the other isomer and the racemate.

Pursuant to the Patented Medicines (Notice of Compliance) Regulations, Sanofi sought to prevent Apotex, a generic drug company, from obtaining a Notice of Compliance from the Minister of Health for a generic version of PLAVIX. Apotex claimed that the ‘777 Patent was an invalid selection patent, was anticipated, obvious and resulted in double patenting in view of the pre-existing ‘875 Patent.

The Court rejected all of the Apotex attacks.

Selection Patents

Justice Rothstein for the Court held that “a system of genus and selection patents is acceptable in principle.” The Court followed a 1930 UK case in finding that they must meet three criteria:

  1. There must be a substantial advantage to be secured or disadvantage to be avoided by the use of the selected members.
  2. The whole of the selected members (subject to “a few exceptions here and there”) possess the advantage in question.
  3. The selection must be in respect of a quality of a special character peculiar to the selected group. If further research revealed a small number of unselected compounds possessing the same advantage, that would not invalidate the selection patent. However, if research showed that a larger number of unselected compounds possessed the same advantage, the quality of the compound claimed in the selection patent would not be of a special character.”

The Court also made it clear that the specification of a selection patent must define in clear terms the nature of the special characteristic which is possessed by the selection claimed.


Apotex alleged that the ‘777 Patent is invalid because the invention was not new or in other words it was anticipated by the ‘875 Patent. The Court refined the previous Beloit test for anticipation for all types of patents to bring it in line with UK authority (the Synthon case in the House of Lords). The new test for anticipation requires that two factors be established, (1) prior disclosure and (2) enablement. The second factor had not been needed to decide the Beloit case.

Prior disclosure means that a single prior publication or patent discloses subject matter which if performed, would necessarily result in infringement. There is no trial and error permitted to determine disclosure. Only if the invention is disclosed is enablement considered.

Enablement means that a person skilled in the art of the invention is able to perform the invention. Enablement permits some trial and error. The Court provided a list of non exhaustive factors to assist in determining how much trial and error is permitted before a prior disclosure will not constitute enabling disclosure:

  1. The prior patent as a whole is to be considered.
  2. Common general knowledge is considered.
  3. The prior patent must provide enough information to allow the invention to be performed “without undue burden” having consideration for the nature of the invention. If invention is required, it is not enabling. Routine trials are acceptable but not prolonged trial and error.
  4. Obvious errors in the prior patent will not prevent enablement.

In the context of the selection patent in issue, the Court found that the ‘875 patent did not disclose the special advantages of the isomer claimed by the ‘777 patent. Consequently, the invention of the ‘777 patent was not disclosed and therefore not anticipated. It was not necessary for the Court to determine whether there was enablement of the invention.

The Court restated the obviousness analyses in the 1985 Windsurfing case in the UK as a useful approach:

  1. Identify the notional “person skilled in the art” and the relevant common general knowledge of that person.
  2. Identify the inventive concept of the claim in question or if that cannot readily be done, construe it.
  3. Identify what, if any, differences exist between the matter cited as forming part of the “state of the art” and the inventive concept of the claim or the claim as construed.
  4. Viewed without any knowledge of the alleged invention as claimed, do those differences constitute steps which would have been obvious to the person skilled in the art or do they require any degree of invention  When considering this step, the issue of “obvious to try” will arise for patents in areas of endeavour where advances are often won by experimentation.

The Court went on to identify a list of non-exhaustive factors to consider in an “obvious to try” analysis:

  1. Is it more or less self-evident that what is being tried ought to work? Are there a finite number of identified predictable solutions known to persons skilled in the art?
  2. What is the extent, nature and amount of effort required to achieve the invention? Are routine trials carried out or is the experimentation prolonged and arduous, such that the trials would not be considered routine?
  3. Is there a motive provided in the prior art to find the solution the patent addresses?
  4. What was the actual course of conduct which culminated in the making of the invention? Was the invention reached quickly, easily, directly and relatively inexpensively? Was time, money and effort expended in research?

In the context of the selection patent in issue the Court found that the ‘777 patent was not obvious. Specifically, the Court found that the ‘777 patent was not “obvious to try” because it was not self evident from the ‘875 patent or common general knowledge what the beneficial properties of the isomer in the ‘777 patent would be. The Court found that Sanofi had spent millions of dollars and several years developing the racemate without testing for any advantages of the isomer of the invention.

Double Patenting

Apotex argued that selection patents would allow patentees to “evergreen” or extend the lives of their patents. The Court found that while evergreening was a legitimate concern it did not generally apply to invalidate selection patents because: (1) a selection patent may be sought by a party other than the patentee; (2) selection patents encourage improvements because the selection does something better and different from the genus patent.

In passing the Court noted that the “sound prediction” of the ‘875 genus patent was not borne out for the other isomer not covered by the ‘777 patent (It was found to be toxic). This means that the “genus patent may be open to challenge” – a cautionary note for drafting genus patents.

The Court found that the claims of the ‘777 patent were not identical or coterminous with those of the ‘875 patent, that the ‘777 patent did not claim the same invention as in the ‘875 patent and the claims were “patently distinct” from those of the ‘875 patent. The Court therefore rejected the allegations of double patenting.


On the surface this case appears to strengthen the rights of patent holders by upholding selection patents and finding on the specific facts of the case that the ‘777 patent was not “obvious to try”. However, the Court has imported into Canadian law less patentee friendly case law from US and UK for the tests for obviousness and particularly, the “obvious to try” test. Researchers are well advised to keep good records including failed experiments. The Courts will now look at the amount of work actually performed by inventors when considering obviousness. This could penalize skilled inventors and reward inefficiency. However, patentees will find the Court’s clarification of anticipation and particularly enablement, will be helpful. These changes are likely to have a substantial effect on the conduct of patent litigation and prosecution of patents in Canada. The harmonization of Canadian law with UK and US law in this case may show a tendency for the Supreme Court to do so in other IP cases.

This article is for information purposes only and does not constitute legal or professional advice.

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Tags: Patents, Pharmaceutical, PM(NOC)