Another Twist on Blinding the Expert

Bristol-Myers Squibb v Teva 2016 FC 580 Mactavish J
            2,250,840 / 2,317,736 / atazanavir / REYATAZ

In a number of recent cases (see here), the parties have tried “blinding” their experts from certain facts in a laudable attempt to reduce the problem of hindsight bias. The Atazanavir decision raised another twist on this practice, which is this subject of today's post. For an overview of the facts, see this post, which also discusses some of the issues related to obviousness; and see this post discussing claim construction.

The point arose in the context of the 840 patent, which claims atazanavir. One of Teva’s experts on obviousness, Dr Romero, was blinded perhaps even more thoroughly than in most previous cases:

[192] Dr. Romero was not told the name of the drug that was at issue in this proceeding, other than the fact that it was a protease inhibitor, nor was she told the names of the parties. She was also asked not to carry out any independent research that might identify the drug in question.

That is, it seems that Teva tried to place Dr Romero in the place of the notional skilled person, trying to solve the problem facing the inventors, without knowledge of their solution. There are a couple of caveats even to this degree of blinding. One is that an expert like Dr Romero cannot forget her own current knowledge, and to the extent that she is familiar with approaches that would not have been common knowledge at the time, she cannot fully avoid the effects of hindsight, even when blinded to the particular facts. Also, as Mactavish J pointed out, “Dr. Romero was provided with a limited selection of the prior art that had been ‘cherry-picked’ by Teva, and her evidence has to be viewed with this in mind” [193]. This point was not merely theoretical; Mactavish J expressed concern that Dr Romero had only been provided with papers dealing with an azapeptide backbone, the class which atazanavir belongs to, and not prior art dealing with other possible backbones [194].

With those caveats, no approach is perfect and this heightened degree of blinding seems to be helpful in avoiding hindsight bias. However, it did not help Teva win its case. The details of Dr Romero's evidence were not spelled out by Mactavish J, but it seems the gist was that there were a finite number of modifications that the POSITA would have made in trying to make a better protease inhibitor [212]. However, Dr Romero proposed some modifications to the backbone which would never have led to atazanavir [195], and

[211] Dr. Romero does not identify which compounds or which substitutions should be made to obtain an improved protease inhibitor in her evidence, or how the POSITA should prioritize them. Importantly, Dr. Romero never states that the POSITA would make the substitutions necessary to get to atazanavir.

In the end, Dr Romero’s evidence may have hurt Teva’s case as much as it helped. The 840 patent survived the obviousness attack, and was ultimately held to be valid.

The fact that blinding the expert did not help Teva in this case helps confirm the value of the practice. If a witness blinded in this manner had arrived directly at the claimed invention, it would seem to be good evidence that the invention was obvious. (Though even this degree of blinding would not be conclusive, in light of the caveats noted above, as well as Locke J’s observation in 2016 FC 382 [46].)