A recent decision of the Federal Court in Allergan Inc. v. Apotex Inc. et al. (2016 FC 344), relating to the drug Gatifloxacin, appears to have regressed the issue of expert “blinding” in patent cases. Expert “blinding” is a relatively recent trend in patent litigation where a litigant intentionally “blinds” its expert witness to certain issues and materials in an effort to afford their opinions a higher degree of credibility. In the Gatifloxacin decision, the Court appears to have endorsed expert “blinding” in patent cases as not only de rigueur but, perhaps necessary; while other recent decisions of the very same Court have seriously questioned the value of the recent trend.

In the Gatifloxacin case, the Federal Court was persuaded by Apotex that Allergan’s expert evidence was flawed by not being properly “blinded”. Allergan’s experts had reviewed Apotex’s Notice of Allegation, as well as the patent-in-suit, prior to preparing their opinions. The Court agreed that the opinions of Apotex’s experts should be preferred over those of Allergen as they were “blinded” from the patent when giving evidence on the common general knowledge, and “blinded” from the parties’ positions throughout.

A few years ago, the “blinding” of experts in patent cases was virtually unheard of. Indeed, one might ask: how could an expert assist a court in understanding, for example, the art and science of a patent and its claims, without having first read the patent-in-suit?

The “blinding” trend gained momentum in some pharmaceutical patent decisions involving Apotex. Indeed, in the Gatifloxacin case, Apotex relied on three of its own cases in support of its “blinding” argument: (i)AstraZeneca v. Apotex2014 FC 638 (“AstraZeneca”); (ii) Teva Canada v. Apotex2014 FC 1070 (“Teva”); and (iii) Takeda v. Apotex2015 FC 570.

These decisions have been distinguished, however, in other decisions of the Federal Court.

For example, in Eli Lilly Canada Inc. v. Apotex Inc., 2015 FC 875 (“Lilly”), published on July 20, 2015, the Court rejected Apotex’s “blinding” argument. The Court found that Apotex had applied the Teva andAstraZeneca decisions “out of context”, noting that “[n]either case can be read for the position that Apotex sought to advance here, namely, that in any case where one party blinds its experts but the other does not, the former’s evidence is to be preferred” and that “these two decisions must be limited to the facts that arose in [those] cases”.

Even more recently, but before publication of the Gatifloxacin decision, the Court held in Shire Canada Inc. v. Apotex Inc.2016 FC 382 (“Shire”) that “favouring the evidence of experts who have been blinded has not been raised to the level of a legal principle that must be applied in all cases, and is merely persuasive”. In addition, the Court noted that “the blinding of witnesses is no guarantee that the expert evidence before the Court is reliable”.

In deciding the Gatifloxacin case, the Court addressed neither Lilly nor Shire on the issue of expert “blinding”. It would appear these cases were not brought to the Court’s attention on this point in the parties’ written arguments.

Accordingly, there may be some difficulty in understanding how these decisions fit together and what, if any, significance can be attributed to the “blinding” of an expert. Nor is there clear guidance in the cases as to how an expert is properly “blinded”. For example, should an expert read the whole of the patent-in-suit or just the claims? If just the claims then which ones: those in dispute or all of them? And, how can the expert assist in determining the characteristics of the person skilled in the art of the patent without reading it, when it is that perspective which is supposed to be brought to bear in reading the claims?

It is possible that the Federal Court of Appeal will soon clarify the issue of expert “blinding”, as the Gatifloxacin decision is currently under appeal.