Obviousness and “Blinding” an Expert

E Mishan & Sons, Inc v Supertek Canada Inc 2015 FCA 163 Webb JA: Ryer, Near JJA aff’g 2014 FC 326 Hughes J
            2,779,882 here

In Mishan v Supertek the FCA has affirmed Hughes J’s finding that the 882 patent is invalid for obviousness. As discussed here, the trial decision largely turned on the the factual issue of whether a particular piece of prior art would have been found in a reasonably diligent search and it is not surprising that the FCA affirmed, using a deferential standard of review [25]. The case does raise an interesting legal point regarding the role of hindsight in the obviousness analysis.

The invention at issue is a lightweight expandable and contractible garden hose, comprising an elastic inner tube and an inelastic outer sleeve. When the hose is empty, the elasticity of the inner tube causes it to contract. When it fills with water, the inner tube expands; since the diameter is constrained by the outer sleeve, it elongates [3]. The key prior art was the McDonald patent, which disclosed a very similar hose, albeit one that was intended as an oxygen hose for an aviation crew oxygen mask. Hughes J found that the 882 invention was obvious over the McDonald patent.

On appeal, Mishan argued [35] that Hughes J had erred by using his knowledge of the 882 Patent to identify the differences between what is claimed in the 882 patent and the McDonald patent and to determine that the differences were obvious, on the basis that this is contrary to the fourth step of the Windsurfing / Pozzoli  test, adopted in Sanofi 2008 SCC 61 [67], which asks whether the invention would have been obvious in light of the state of art “viewed without any knowledge of the alleged invention as claimed.” There is considerable force to Mishan’s argument. As Lewison J explained in Virgin Atlantic 2009 EWHC 26 (Pat) [271-72]:

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. . . . If an expert approaches his own task in the manner set out in Pozzoli, he will almost inevitably expose himself to a charge of having approached the final question with the aid of hindsight.

The FCA nonetheless rejected Mishan’s submission, pointing out that the difficulty is inherent in the Windsurfing / Pozzoli framework:

[36] 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 the statement that the fourth step of the test must be undertaken “without any knowledge of the invention as claimed” cannot be understood literally. It is really just an awkward way of repeating the standard warning against being influenced by hindsight: see eg Wandscheer [1948] SCR 1 at 12.

Though the FCA was bound to reject this objection as a matter of law, what about as a matter of policy? Is there any alternative? Lewison J said in order to avoid the problem of hindsight bias, “[t]he structured Pozzoli approach is a series of steps directed to the court; not to experts” [272]. But this does not solve the hindsight bias, as it is empirically well-established that judges are also subject to the hindsight bias – if anything, to a greater extent than experts in the art.

One alternative approach would be to “blind” the expert to the invention, by asking them to answer the problem addressed by the inventor without knowing the inventor’s solution. In this case, we would simply ask the experts – or rather a skilled person – to design a lightweight expandable and contractible garden hose, and see if they come up with the invention. This would avoid hindsight by asking each expert to fully replicate the inventive process faced by the inventor. But if done faithfully, this would often be unworkable, as the cost of litigation could exceed the cost of invention. With that said, “blinding” the expert to the solution might be workable in some cases, such as where the question is whether the invention is obvious to try; if the expert is blinded and yet readily suggests a route that in fact worked without difficulty, this would be good evidence that the proposed route was indeed obvious to try: see eg Esomeprazole 2014 FC 638 [321].

This relates to the question of whether experts should be blinded in claim construction. As discussed here, in her Rasagiline 2014 FC 1070 decision, Gleason J indicated at [94]-[97] that the blinding of the Apotex experts in that case was reason to prefer their evidence over that of Teva’s experts. But more recently, in Apotex / Tadalafil 2015 FC 875 [166], she explained in effect that both her Rasagiline decision and Rennie J’s Esomeprazole decision turned on the facts. That is, blinding is not always preferred, though in some circumstances it might be preferred. This seems right to me. There is a tradeoff between avoiding the hindsight problem and keeping costs of litigation manageable by focusing on “where the shoe pinches,” and how that balance is best achieved will depend on the facts. Unfortunately, that means there is no easy way to for a litigant to decide whether to blind its experts in a particular case.(Note that Rasagiline concerned claim construction while Esomeprazole and Tadalafil concerned obviousness.)