On November 6, 2008, the Supreme Court of Canada released its decision in Apotex Inc. v. Sanofi-Synthelabo Canada Inc. et al.1 on an appeal from the Federal Court of Appeal decision upholding the Federal Court order of Shore J. granting an order of prohibition in a Patented Medicines (Notice of Compliance) Regulations proceeding in respect of the drug, clopidogrel bisulfate. Clopidogrel is the dextro-rotary isomer selected and claimed in the patent at issue from the racemate disclosed in the earlier genus patent. It is more active, less toxic and better tolerated than the racemate or levo-rotary isomer.

The Supreme Court dismissed Apotex's appeal and in so doing:

  1. affirmed the legitimacy of selection patents that claim one or more compounds from a broader genus claimed in an earlier patent;
  2. refined the analysis of the question of anticipation to a two-step process where the necessity for the prior disclosure of the invention and enablement of the invention by the prior disclosure is separately considered;
  3. refined the analysis of obviousness to a four-step process suggested in an earlier U.K. decision and contrary to earlier cases, stated that the U.K. "obvious to try" test had some application in Canada; and
  4. held that concern over "evergreening" patents by double patenting did not warrant invalidating selection patents as a legitimate class of invention.

Selection Patent Criteria

Briefly, selection patents are valid if:

  1. the selected compounds, though encompassed by the genus, had not been actually made before;
  2. there is a substantial advantage to be had or disadvantage to be avoided by using the selected group;
  3. all of the selected members have the advantage or avoid the disadvantage; and
  4. the special character is peculiar to the selected group, i.e. a large number of unselected members could not have the special character.

Test for Anticipation

The accepted test applied by Canadian courts is based on a line of cases summarized in Beloit v. Valmet2 and approved by the Supreme Court in Free World Trust v. Electro Santé3 as being:

The prior publication must contain so clear a direction that a skilled person reading and following it would in every case and without possibility of error be led to the claimed invention.4

Added to this test are separate considerations of prior disclosure and enablement.

Prior disclosure means that the prior patent must disclose subject matter which, if performed now, would necessarily result in infringement. At this stage there is no trial and error experimentation; it is just being read by the skilled person to understand it. Prior disclosure in the context of a selection patent means that the special advantages must have been previously disclosed.

Enablement means that the skilled person would have been able to perform the invention. Routine trial and error to get it to work would be permitted at this stage, but it cannot be an undue burden that requires either an inventive step or prolonged or arduous trial and error.


Reviewing recent developments in the U.K. and U.S. on obviousness, the test in Canada was refined to make room for some application of the "obvious to try" test used in the U.K.

The inquiry becomes:

  1. a) Identify the notional person skilled in the art.

b) Identify the relevant common general knowledge.

  1. Identify the inventive concept of the claim or construe it.
  2. Identify the differences between the state of the art and the inventive concept as construed.
  3. Without reference to the invention, do the differences constitute steps that would be obvious to a skilled person or do they require invention?

"Obvious to try" comes in the fourth stage. Whether something is obvious to try has several factors:

  1. Is it more or less self-evident that what is being tried ought to work?
  2. What is the nature, extent and amount of effort needed (i.e. quick and routine or prolonged and arduous)?
  3. Is there a motive in the prior art to find the solution in the patent?

The actual course of conduct, i.e. what people were actually doing in the field at the relevant time, can be considered.

Double Patenting

The concern about "evergreening" and an attack on selection patents as allowing such evergreening was rejected for two reasons:

  1. a selection patent may be sought by someone other than the owner of the genus patent so that "evergreening" does not arise; and
  2. selection patents encourage improvements by identifying particular members with beneficial properties over a generalized genus.

This case is very important to patent practitioners as it expressly refines or updates crucial patent concepts of obviousness and anticipation used in opinion, prosecution and litigation alike.