Taking the Exudate - ConvaTec v Smith & Nephew [2011] EWHC 2039 (Pat)

Seeping wounds: not the name of a village in the West Country (the Kat has checked), and neither is it the most savoury of subjects for polite after-dinner conversation. However, it does form the background for the decision in Convatec v Smith & Nephew [2011] EWHC 2039 (Pat), handed down this morning by HHJ Birss – the Judge having discarded his usual Patents County Court hat for the matter and donned that of a Judge of the High Court.

When but a kitten, one of the first things that one learns about tearing around the place with reckless abandon is the fact that most inanimate objects simply cannot be trusted. Apparently immovable, this Kat lost count of the number of playgrounds and trees that conspired to take large chunks out of his paws, elbows and knees by subtly reorientating themselves in respect of his person at a critical point during a daring manoeuvre. Needless to say: there were often cuts and grazes, blood and associated ooze. Anyone that has suffered from high-speed playground contact syndrome will appreciate that the damage caused is usually relatively slight, and the blood loss low. The ooze factor, however, is high, and many a good pair of trousers has been the source of significant pain and discomfort by becoming firmly adhered to the graze site. Wounds, you see, seep, and fabric tends to stick to this seepage.

So back to the case in hand. ConvaTec own a number of patents relating to wound dressings. The patent in suit (EP(UK) 0 927 013) concerned a non-adherent dressing comprising certain fibrous material that operated to absorb wound exudate (i.e. seepage) whilst maintaining a moist environment around the wound. Keeping a wound moist is generally agreed to aid healing, but too much moisture is a bad thing as it can lead to maceration (i.e. over-hydration) of the surrounding skin. Accordingly, at the priority date of the patent there were a number of wound dressings on the market that promoted the maintenance of a moist wound environment by gelling – absorbing the exudate and forming a gel within the dressing itself.

Smith & Nephew wished to sell a wound dressing called Durafiber. ConvaTec alleged that this would infringe their patent, and so brought an action against them. Smith & Nephew, for its part, denied infringement and counterclaimed for revocation on the ground of invalidity.

Having orientated himself by considering the technical background to the invention, the identity of the skilled addressee and their common general knowledge, the Judge then addressed the issue of construction. Distinct issues of construction arose in respect of claims 1 and 3 of the patent:
Claim 1:
A wound dressing comprising a blend of discrete modified cellulose gel forming fibres with at least one other type of discrete gel forming fibres.
Claim 3:
A wound dressing as claimed in any preceding claim wherein the dressing comprises a wound contacting surface consisting of a blend of discrete modified cellulose fibres with at least one other type of discrete gel forming fibres.
Setting out the law, the Judge adopted the tried and trusted formulation found in Kirin Amgen Inc v Hoechst Marion Roussel [2004] UKHL 46, [2005] RPC 9, and also recited the 11-point plan endorsed by the Court of Appeal in Virgin v Premium Aircraft Interiors [2009] EWCA Civ 1062, [2010] RPC 8. When addressing claim 1, he explained that there 2 issues of construction: the first was the meaning of “blend of discrete fibres” and whether this rendered it a product by process claim; and the second was the meaning of the word “type”.

Rejecting the contention that claim 1 would be understood by a skilled reader to refer back to the process by which the product was made, the Judge explained that it was a simple product claim:
[55] “…The claim is a claim to a thing – a wound dressing. The thing comprises a blend of (at least) two types of discrete fibres. In other words a mixture of discrete fibres.”

[57] “No doubt the reader would expect it to be likely that one would make such a wound dressing by mixing (blending) the two fibre populations but that processing is not what the claim is talking about. The claim is talking about a product…. The reader would understand that the invention is about using the mixture of fibres which gives beneficial properties as a wound dressing. It is not an invention focussed on manufacturing methods. How you choose to make the mixture is irrelevant.”
Moving on to the construction of “type” within claim 1, the Judge noted (at [60]) that ConvaTec had argued that “type” referred to fibres with different absorbency properties. Smith & Nephew, by contrast, contended that “type” referred to a particular polymer – i.e. to the chemistry of the fibre. In a rather radical move, the Judge considered that “both the claimants’ and the defendants’ submissions are wrong.” He explained that
[63] “The flaw in each side’s submission is to approach the matter as one of construction of the word “type”. Type is a perfectly ordinary English word which ordinarily would not be expected to bear the kind of refined analysis each side have subjected it to. The key it seems to me is to appreciate that the correct question is to construe claim 1. Claims should, if they can, be construed as a whole.”
Accordingly, by focussing on the meaning of one word within the claim, the parties had missed the way in which claim 1 was written. As this Kat has long maintained, the process of atomising phrases within the claims is capable of distorting the message conveyed by the whole. The natural tendency when faced with a deconstructed sentence is to treat the individual particles as elements of precision. One assumes that the message conveyed by the whole is simply the sum of its parts, whereas often the true story is much more complicated. Or, as in this case, much simpler: accordingly as the Judge explained –
[65] “…[C]laim 1 is actually rather simple. If all the gelling fibres in the wound dressing are modified cellulose then the claim is not satisfied. The claim requires a blend of (gel forming) modified cellulose fibres and some other type of fibres, that is to say some other fibres which are not modified cellulose. If I ask in a shop for a bowler hat and another type of hat, I do not expect to be given two bowler hats, differing only in their size or colour or whatever.”

[66] “…Asking, out of the context of claim 1, what a “type” is, is an example of meticulous over analysis of the words. Once you embark on asking the (wrong) question of what is a type, there is support in the specification for many different answers.”
Moving on to claim 3, the Judge explained that the term “modified cellulose fibres” was not a term of art and was “not a term which reader would think was meant to impose a tight limitation. The term is broad and is not intended to be limiting.” Accordingly, it was not limited to chemical modifications.

Given the Judge’s construction of the claims, there was evidently no infringement:
[104] “The only gel forming fibres in Durafiber are made of CES, i.e. modified cellulose. In other words, as regards gel forming fibres, Durafiber uses modified cellulose alone and there is no other type of gel forming fibre present. Therefore on the true construction of the claims, Durafiber does not infringe claim 1.”
[105] “Moreover since claim 3 is dependent on claim 1, Durafiber does not infringe that claim either, irrespective of the issues of construction of claim 3.”
Moving to validity: by the end of the trial ConvaTec had accepted that claim 1 of the patent was anticipated and therefore invalid. Claim 3, stated to have independent validity, was attacked on grounds of obviousness – it being alleged to lack inventive step over three pieces of prior art (Qin, Lassen and ‘746) and the common general knowledge. Diving in to the issues, the Judge applied the Pozzoli reformulation of the classic Windsurfing test and sought to apply this to the facts. In respect of the first two pieces of prior art (Qin and Lassen), claim 3 passed muster – it was not obvious in their light. ‘746 deserves special mention.

‘746 was a PCT application published about a year before the priority date of the patent in suit. It is entitled “Wound dressings” and relates a wound dressing employing CMC (i.e. carboxymethyl cellulose – modified cellulose) fibres in the wound contacting surface. On the Judge’s construction the point did not arise, however, on ConvaTec’s proposed construction – assuming that the defendants’ product did infringe the claims – then it was alleged that the product of ‘746 would also fall within the patent’s scope of protection. As such, the patentees were evidently on the classic “horns of a dilemma”: the defendants alleging that there was nothing patentably distinct between ‘746 and their actions which were alleged to infringe. As the judge noted (at [170]) this was “a Gillette defence of the purest kind.”

Nevertheless, as construed by the Judge, the patent was safe from these challenges. It was also not obvious in light of the common general knowledge – this being a case in which one could legitimately ask “if it was obvious why was it not done before?”

Accordingly the patent was valid, in part, but not infringed.


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