Pot-shots from the sidelines not enough to disprove inherent anticipation

On June 15, 2015, Justice Barnes released his public Judgment and Reasons in a prohibition application involving Mylan and Canadian Patent No. 2,341,031 listed on the Patent Register against Takeda’s pantoprazole product, TECTA. The 031 Patent is generally directed to pantoprazole magnesium dihydrate.

Mylan raised a number of invalidity allegations, but the case ultimately turned on the issue of inherent anticipation.


Justice Barnes adopted a construction of claim 1 of the 031 Patent that was inconsistent with all of the expert evidence. Every expert construed claim 1 to include all polymorphic forms of pantoprazole magnesium dihydrate. Justice Barnes stated that the construction of the patent is an issue of law for the Court to determine, with the role of experts being to assist in this exercise. Justice Barnes held that the person of skill would be more likely to read Claim 1 to include only the dihydrate forms the inventors discovered.

Inherent Anticipation

A piece of prior art that formed the basis for the anticipation allegation described a process for preparing magnesium salts of certain benzimidazoles including pantoprazole. The example did not explicitly disclose that the produced compound was pantoprazole magnesium dihydrate. Justice Barnes discussed the relevant jurisprudence on anticipation and held that the claims in issue would not be anticipated if, on a balance of probabilities, Takeda could show that following the prior art did not inevitably or necessarily produce pantoprazole magnesium dihydrate.

The court was satisfied that Mylan’s expert followed the process described in the prior art example and ended up with pantoprazole magnesium dihydrate. In addressing Takeda’s criticism of Mylan’s experimental testing, Justice Barnes, following his previous decision in Apotex omeprazole, held

[49]   It was, of course, open to Dr. Myerson to run his own experiment using his preferred methods, and to characterize the hydration state of the resulting compound. Presumably he was directed by Takeda not to take that step. Instead Dr. Myerson raised only theoretical concerns about Dr. Atwood’s methods without saying how those choices would be likely to produce something other than a dihydrate. In AstraZeneca Canada Inc v Apotex Inc, 2015 FC 322, 252 ACWS (3d) 567, I expressed some reservation about that type of strategic choice:

[361]    The fact that a party may not agree with a chosen experimental design is not an excuse for failing to replicate the work to test the reliability of the reported data. The same applies to criticisms about the testing techniques employed by an opposing expert witness. An argument that other tests or controls could have been used loses much of its strength where a party chooses not to employ those same suggested methods in its own responding analysis to see if the results differ.

I would add, in the face of Takeda’s failure to conduct a single test, its concern that Dr. Atwood only ran one is somewhat of a dissimulation.

Non-infringement – Hearsay Analysis

Justice Barnes also included a discussion of hearsay evidence in the context of NOC proceedings. Takeda argued (and the Court agreed) that a piece of evidence relied upon by Mylan’s experts was inadmissible hearsay. However, Barnes stated that “given the summary nature of NOC proceedings…some latitude should be extended to the reliance by expert witnesses upon hearsay contained within authenticated and facially reliable scientific references”.

A copy of the decision can be found here.