Wise after the event: does expert evidence induce hindsight?

Another warning about the relationship between expert evidence, inventive step and hindsight was delivered by the Court of Appeal for England and Wales in Apimed Medical Honey Ltd v Brightwake Ltd [2012] EWCA Civ 5, in which that court allowed an appeal against a decision of Judge Michael Fysh QC.

Apimed's patent specification described a medical composition for a wound dressing made mainly of honey, which was combined with a "gelling agent" so as to result in a flexible sheet or pliable putty that could be made to fit a wound. The specification gave examples, the majority of which used sodium alginate as a gelling and viscosity increasing agent. Judge Fysh found the patent to be technically simple: the skilled addressee, who would already be carrying out  research and development of contemporary surgical dressings, could rely upon a consultative combination with persons concerned with the in situ treatment of wounds with commercially available dressings such as tissue viability nurses and specialist consultants. According to the judge, the skilled addressee did not include alginate chemists, rheologists, epidemiologists, materials scientists or honey experts. Judge Fysh then construed the phrase "natural based gelling agents" as meaning not only agents causing the honey to form a gel, but also agents causing an increase in the viscosity of the honey sufficient to allow it to be made into a putty or rolled sheet. Finally, based on evidence from (i) a tissue viability nurse that she had been adding honey to alginate dressings for approximately 10 years before the patent date, and (ii) an earlier article about the role of honey in the management of wounds, the patent was obvious because the availability of alginate dressings was commercial and their use was common general knowledge.

Allowing Apimed's appeal, the Court of Appeal (for whom Lord Justice Kitchin delivered the judgment) took the view that Judge Fysh had accepted expert evidence that an obvious way to address the application and retention of honey was to make it thicker by use of a thickening agent, and that alginate was an obvious candidate because of being commonly used in the wound environment. However, he had not considered that the only way alginate was used in the wound environment was in the form of calcium or sodium-calcium alginate pads, which did not act as a gelling agent as called for by the claim. The Court of Appeal drew attention to the words of Mr Justice Kitchin (as he then was) in Abbott Laboratories Ltd v Evysio Medical Devices UCL [2008] EWHC 800 (Pat), [2008] RPC 23, where he said (at para 180):

" ...  It is also particularly important to be wary of hindsight when considering an obviousness attack based upon the common general knowledge. The reason is straightforward. In attacking a patent, attention is focused upon the particular development which is said to constitute the inventive step. With this development in mind it may be possible to mount an attack which is unencumbered by any detail which might point to non obviousness: Coflexip SA v Stolt Comex Seaway Ltd (CA) [2000] IP&T 1332 at [45]. It is all too easy after the event to identify aspects of the common general knowledge which can be combined together in such a way as to lead to the claimed invention. But once again this has the potential to lead the court astray. The question is whether it would have been obvious to the skilled but uninventive person to take those features, extract them from the context in which they appear and combine them together to produce the invention".