Earlier this month we saw contrasting decisions on the practice of blinding expert witnesses from Zinn J in Allergan v Apotex 2016 FC 344 (blogged here) and Locke J in Shire v Apotex 2016 FC 382 (blogged here). Just days later, the decision of Arnold J in AS&E v Rapiscan addressed the same question. The invention related to an X-ray security scanning system for use at borders. The main question was the obviousness, and both the patentee, AS&E, and the defendant Rapiscan, introduced expert evidence. They both blinded their experts, but in slightly different ways, neither of which was satisfactory according to Arnold J, who made the following general comments on the expert evidence:
109. Each party contends that the other party instructed its expert to ask himself the wrong question. Both sides’ solicitors proceeded in a carefully structured manner by first asking their expert to consider the person skilled in the art and the common general knowledge, then to consider the prior art relied upon by Rapiscan and only then to consider the Patent. The difference between them was that AS&E’s solicitors asked Dr Bjorkholm to consider obvious developments of the prior art before showing him the Patent, whereas Rapiscan’s solicitors only asked Dr Lanza to consider the question of obviousness after they had shown him the Patent.
110. In my view there is force in the criticisms which each side levels at the other’s approach. The approach adopted by AS&E’s solicitors had the advantage that it enabled Dr Bjorkholm to consider obvious developments of the prior art free from knowledge of the Patent; but it meant that he never addressed in his reports the question of whether the differences between Swift and the claimed invention constituted steps which would have been obvious to the person skilled in the art. The mere fact that a step did not occur to Dr Bjorkholm when reviewing the prior art was not sufficient to exclude the possibility that he might agree that it was obvious if asked. Unlike the person skilled in art, real people sometimes miss the obvious.
111. The approach adopted by Rapiscan’s solicitors avoided that difficulty. The problem is that, whereas the correct question is whether, viewed without any knowledge of the claimed invention, the differences constituted steps which would be obvious, Dr Lanza expressed his understanding of the question he had been asked to consider without referring to the need to exclude knowledge of the claimed invention. Moreover, this does not appear to have been an artefact of the drafting of the report. On the contrary, Dr Lanza confirmed in cross-examination that his approach had been to consider obviousness as if the skilled person had been shown the claims and asked if they were obvious. Thus Dr Lanza does not appear to have understood the importance of trying to avoid hindsight.
AS&E’s expert was untainted by hindsight, but for precisely that reason he was unable to focus on “where the shoe pinches.” Rapiscan’s expert could focus on the crucial question, but his evidence was affected by hindsight. Could the problem have been avoided if Rapiscan had emphasized to their expert the importance of trying to avoid hindsight? I don’t think so. As I recall the research on the hindsight bias, being instructed to avoid hindsight does not significantly mitigate the bias.
The problem is inherent in the Windsurfing/ Pozzoli approach to the obviousness, endorsed by the SCC in Sanofi 2008 SCC 61, . As Lewison J noted in Virgin Airways v Premium Aircrafts Interior 2009 EWHC 26 (Pat) at :
Although the structured approach is relatively easy to describe, it can be very difficult to apply. One reason for this is that at the third stage of the structured approach it is necessary to focus on the differences between the prior art and the patent in suit; but at the immediately succeeding fourth stage it is necessary to erase all knowledge of the alleged invention from the mind. That is not an easy task.
“Not easy” is polite; "impossible" would be more accurate.
The FCA also recognized the problem in E Mishan & Sons, Inc v Supertek Canada Inc 2015 FCA 163 (blogged here):
 In applying the fourth step of the Sanofi test, in my view, the requirement that this step be completed “without any knowledge of the alleged invention as claimed” does not mean that the differences that were identified in step 3 would be forgotten for step 4. These differences are an essential part of step 4. Without knowing the differences between the relevant prior art and the inventive concept, step 4 could not be completed. The differences are based on the inventive concept of the claims in issue and the relevant prior art and, therefore, are determined based on some knowledge of what is claimed in the patent in issue. Therefore, some knowledge of the alleged invention will be reflected in the differences that are analyzed in applying step 4 of the Sanofi test.
Thus a expert who is blinded as in AS&E’s approach cannot apply the Windsurfing analysis, but an expert who is not so blinded will have their evidence tainted by hindsight.
Pick your poison.