One feature of UK patent litigation is the use of party-appointed experts to provide evidence to assist the Court when deciding issues in patent cases. On the question of obviousness, for example, the Court has to adopt the mantle of the person skilled in the art at the priority date, clothed with common general knowledge at that time, and decide (avoiding hindsight) whether the steps from the prior art to what is claimed involved an inventive step. In the 11 April 2016 judgment in American Science & Engineering Inc v Rapiscan Systems Ltd [2016] EWHC 756 (Pat) the judge commented on how the parties' experts were engaged. The Court provided guidance that the expert should not be shown the patent initially. The expert should first give their evidence on the common general knowledge of the person skilled in the art at the priority date; then be provided the prior art to comment on what it discloses; and then should be asked what steps it would be obvious to take in light of the common general knowledge. Once the expert has given that evidence, the patent may be provided to the expert. At that point, the expert can go back to address obviousness again, identifying points of difference between the prior art and what is claimed in the patent and answering whether those steps (without hindsight) involved an inventive step or were obvious.

Taking the approach identified by the Court may assist in avoiding criticism of the expert's evidence on obviousness. In some fields the way the expert is instructed on questions may not be quite so critical. For example, experts in some aspects of mobile phone technology may already be familiar with the technical solution to the problem that the prior art was addressing at the time because they know the technical solution adopted in the standard. As a further comment, it is not necessarily decisive whether or not an expert shown the prior art says the claimed invention of the patent is obvious. The Court is assessing obviousness adopting the mantle of a hypothetical person skilled in the art at the priority date. The expert is only an approximation to that hypothetical legal construct. Thus, the expert who says something is obvious to him/her before seeing the patent may, in fact, be taking some inventive step unwittingly or taking into account impermissible information. Conversely, the expert who does not mention as obvious what is claimed in the patent, may simply have overlooked what the hypothetical person skilled in the art would have identified without invention.

The content of this article is intended to provide a general guide to the subject matter. Specialist advice should be sought about your specific circumstances.