The Supreme Court of Canada has upheld Sanofi’s PLAVIX patent rejecting generic drug maker Apotex’s appeal in Sanofi v. Apotex 2008 SCC 61. But in doing so, the Court changed Canadian law in light of that of the UK and recently in the US, and the question is whether it will signal a shift in the law of obviousness against upholding patents. It is the Supreme Court’s first intellectual property decision since 2007, when it decided Euro-excellence Inc. v. Kraft Canada 2007 SCC 37, following its busy year for IP in 2006.

In PLAVIX, Justice Rothstein, for a unanimous Supreme Court, re-wrote the Canadian law of anticipation and obviousness. Apotex attacked Sanofi’s selection patent for its blockbuster blood thinner on the basis that it was already included in an earlier first published Sanofi patent for a huge class of such compounds. Included in the first Sanofi patent were racemates and their enantiomers. Racemates are made up of two structurally different but related compounds called enantiomers. PLAVIX is an enantiomer. Both the PLAVIX enantiomer by itself and the racemate of which PLAVIX was one of the two constituents were the subject of the first patent along with hundreds of thousands of others.

Sanofi tried initially to develop that racemate, but it was a clinical failure because of toxicity. Sanofi decided to look at the enantiomers of the racemate and found that one of them (PLAVIX) had much improved efficacy and decreased toxicity, and the other poor efficacy and significant toxicity. Beforehand whether one enantiomer would be an improvement in these respects was unknown, and obtaining the enantiomers for this evaluation took considerable time and effort. Sanofi then took out a second patent for the selection of PLAVIX on the basis of its superior properties from the large class and over the racemate of which it was one of the two constituents.

On anticipation, the Court adopted the UK House of Lords in Synthon v. SKB [2006] RPC 10 overruling its own quite recent pronouncement on anticipation in Free World Trust v. Électro Santé Inc. 2000 SCC 66. Under Synthon a patent is anticipated if the prior art firstly discloses the invention in that practicing the prior art would infringe the patent under attack, and secondly enables the invention in that it teaches how to practice it and no inventive step is needed. The Synthon test had already been adopted on the disclosure point by the Federal Court of Appeal in another case, Abbott v. Ratiopharm 2006 FCA 187 so this is not a significant change.

On obviousness the Supreme Court overruled long-standing authority rejecting “worth a try” to align it with the UK and US. The law of the UK is now to be followed. This includes “worth a try” which will apply in fields where there is experimentation such as pharmaceuticals but according to Justice Rothstein will only succeed where it is “self evident” that what is being tested ought to work.

“Obvious to try” has long been the law of the UK, and in KSR the US Supreme Court held it could invalidate in appropriate cases similar to what Justice Rothstein said. Our US colleagues tell us that KSR has tipped the balance against upholding patents in the lower courts in the US. The UK is reputed for being patent hostile due to “worth a try” especially for chemical and pharmaceutical patents. But if the PLAVIX decision is followed fairly, it should not have these effects in Canada. In substance there is not much change.

In the result, Sanofi’s PLAVIX patent was neither anticipated nor rendered obvious by its first patent under the new tests so the outcome was the same as in the lower courts.

Lastly, double-patenting was decided according to whether the patents had coterminous claims (they did not), and whether the second invention is obvious over the first which was already decided in Sanofi’s favour. The approach on double patenting followed the Court’s own decision in Whirlpool Corp. v. Maytag Corp. 2000 SCC 68.