The Court of Appeal's decision in Apimed Medical Honey Ltd v Brightwake Ltd(1) provides a useful overview of the correct principles to be applied when assessing common general knowledge and obviousness. In such cases, where a successful appellant has the validity of its patent restored, it should seek a certificate of contested validity from the court.
Recent studies have provided clinical evidence that certain types of honey, particularly manuka honey, are effective in treating serious wounds where bacteria have developed a resistance to conventional treatments. However, the physical properties of honey make it difficult to use as a wound dressing.
Apimed Medical Honey Ltd invented a solution to this problem by combining the honey with alginate powder. This causes a change in the honey's physical state, allowing it to be made into a pliable putty or rolled into a flexible sheet, both of which can be easily applied to a wound. Apimed's patent for this invention is European Patent (UK) 1,237,561 for "medical dressings comprising gelled honey".
Apimed issued a claim against its former licensee, Brightwake Limited, for infringement of the patent. Brightwake denied infringement and counterclaimed for revocation of the patent on the grounds that it was obvious and not novel. The case was heard in the Patents County Court. Judge Fysh found that the patent was not infringed and was invalid for obviousness. Apimed appealed to the Court of Appeal.
Owing to a settlement between the parties before the appeal hearing, the only issue to be determined by the court was whether the patent was valid. Brightwake did not oppose Apimed's appeal on this point and played no part in the appeal hearing. From a public policy perspective, an uncontested appeal on validity is undesirable, as it increases the risk that an invalid patent is restored to the register of patents (because the appellant's submissions on the patent's validity go unchallenged). Therefore, the comptroller general of patents appeared before the court to make submissions on behalf of the public interest.
The appeal judgment, given by Lord Justice Kitchin, clarified the main principles to be applied by the court when it is asked to consider whether a patent is invalid for obviousness.
The court held that a patent specification is addressed to those likely to have a practical interest in the subject matter of the invention in question, as well as practical knowledge and experience of the kind of work in which the invention is intended to be used.(2) It is this 'skilled addressee' who must be considered for the purpose of assessing obviousness and sufficiency. However, the court also noted that where the patent is "art changing", the person skilled in the art may not be the same for the purposes of obviousness on one hand and claim interpretation and insufficiency on the other.(3)
It was also held that as a matter of law, the skilled addressee is deemed to read the prior art with at least some level of interest.(4) Therefore, persons skilled in the art in this case should be deemed to have some interest in the possible use of honey in modern wound care.
Common general knowledge
The court ruled that the common general knowledge of the skilled addressee is all that knowledge which is generally known and generally regarded as a good basis for further action by the bulk of those engaged in a particular art. It also stated that it could go further, to include:
"all that material in the field he is working in which he knows exists, which he would refer to as a matter of course if he cannot remember it and which he understands is generally regarded as sufficiently reliable to use as a foundation for further work or to help understand the pleaded prior art."(5)
Obviousness over prior art
The court held that although the trial judge had been correct to follow the steps in Pozzoli SpA v BDMO SA(6) when assessing whether a patent is obvious over prior art, he had erred in applying the steps. The Pozzoli steps are to:
- identify the notional person skilled in the art and the relevant common general knowledge of that person;
- identify the inventive concept of the claim in question or, if that cannot readily be done, construe it;
- identify what, if any, differences exist between the matter cited as forming part of the state of the art and the inventive concept of the claim (or the claim as construed); and
- determine whether, viewed without knowledge of the alleged invention as claimed, such differences constitute steps which would have been obvious to the person skilled in the art or whether they require a degree of invention.
It was held that the trial judge had not correctly identified the differences between the state of the art and the inventive concept of the claim. Consequently, he had failed to identify correctly whether the differences constituted steps which would have been obvious to the person skilled in the art or whether they required a degree of invention. On that basis, the appeal was allowed, the patent was held to be valid and the court ordered a certificate of contested validity.
Although the decision does not raise new principles of law, it provides a useful summary of the correct approach for a court to take when assessing whether a patent is obvious. It also highlights that a possible consequence of a successful appeal on invalidity is that the court orders a certificate of contested validity. This can be of commercial value to a patent owner (eg, when negotiating future licences), as the validity of its patent has been proven and can be seen by the world at large - the certificate is entered on the register of patents at the Intellectual Property Office. This may also deter future infringers, as a defence of invalidity in a subsequent action would be pointless (if run on similar grounds to the unsuccessful challenge). Furthermore, if a defendant in a subsequent action were to proceed with a validity challenge and lose, it could be liable to pay the claimant's costs on an indemnity basis.
For further information on this topic please contact Clive Thorne or Henry Priestley at RPC by telephone (+44 20 3060 6000), fax (+44 20 3060 7000) or email (email@example.com or firstname.lastname@example.org).