Vericore Ltd v Vetrepharm Ltd & Anor

This is the appeal of Vericore Ltd, the patentee of UK patent GB 2,270,261, from the decision dated 18 March 2002 of Mr Dennehey, Divisional Director, acting on behalf of the Comptroller, by which he held that patent to be invalid. The grounds on which he found for the respondents, Vetrapharm Ltd and Alpharma, were that claims 1 and 4 of the patent were not novel in the light of certain of the pleaded prior art and that, even had they been novel, all the claims were obvious. Although he expressed the preliminary view that there was unlikely to be anything inventive which could be salvaged from the patent, he gave Vericore permission to apply to amend. The issue of amendment has been stayed pending the outcome of this appeal.

This appeal is governed by paragraph 16 of the Patent Practice Direction pursuant to CPR Part of 52, rule 11 and CPR Part 49. It is therefore a rehearing but the appellate court will give great weight to the decision below. This is particularly true in relation to issues of fact which are dependent on, or significantly affected by, the evidence of witnesses and experts who have been cross-examined in the court or tribunal of first instance. In the present case, the hearing before Mr Dennehey lasted for three days and it included cross-examination of a number of those who had given written evidence. Mr Dennehey made findings as to the reliability of witnesses and the oral evidence given which have not been challenged. Indeed Mr David Young QC who, together with Mr Geoffrey Pritchard, appears here, as they had appeared before Mr Dennehey, on behalf of Vericore, says that he does not seek to challenge Mr Dennehey’s assessment of the witnesses nor does he seek to challenge his findings of “primary fact”. Furthermore, I understand Mr Young to advance no serious criticisms directed at Mr Dennehey’s recitation of the legal principles involved in this case. It is the application of those principles which is challenged on this appeal.

The patent is concerned with providing a solution to the problem of sea lice infestation which can be of particular concern were high densities of salmonid fish are to be found. The technical field of the patent is described as follows in the decision:-

The patent describes the relevant background to the invention in three paragraphs. First it says:-

There is nothing to suggest that any of this was not well known to those in the art at the priority date of the patent, namely 18 March 1991. In particular the toxicity of dichlorvos was well known and it was well known that it had to be administered at a concentration which was high enough to kill the lice but not so high as to kill the fish. As this paragraph points out, the safety margin for this insecticide was quite small. The patent then proceeds as follows:-

The nature of the invention is then described:-

The inventor does not claim to understand the factors which make the invention work. This is apparent from the following paragraph:-

The patent goes on to set out a number of examples which are said to illustrate the invention. I will have to consider these later in this judgment. Towards the end of the specification, the following passage is to be found:-

There are 14 claims. Before Mr Dennehey no concession was made that any of these lacked independent validity. In the result, the validity of each was considered and found wanting. On this appeal Mr Young has only asserted independent validity for Claim 1 and claims 6, 8 and 9. He says that the latter 3 claims survive or fall together. The claims in contention read as follows:-

I can now turn to the decision. As I have said, Mr Dennehey held all the claims to be invalid for obviousness over some of the pleaded prior art and claims 1 and 4 to be invalid for anticipation. The Applicants had advanced certain other attacks which failed. Mr Hacon, who appears, as he did below, for the respondent applicants, has not sought to advance any cross-appeal nor have his clients put in a respondents’ notice. They say that the conclusions and reasoning of Mr Dennehey were in all material respects correct.

Mr Dennehey has produced a model decision. His analysis of the facts and the law are clear and, save perhaps on one or two very minor factual points, unimpeachable. Indeed I have considered whether I should simply adopt the words used by Lord Diplock in Polaroid Corporation (Land’s) Patent [1981] FSR 578 and say that the decision below is obviously right and expressed in terms so clear and convincing that I do not think I can improve on them. However, out of deference to the arguments advanced by Mr Young, some of which may not have been put to Mr Dennehey, I shall consider below the major issues canvassed on behalf of Vericore and the reasons why I have come to the conclusion that Mr Dennehey’s decision is correct.

Two major arguments are put forward. The first is concerned with terminology. It will be seen that the patent and its claims refer throughout to “pyrethroids”. Two pieces of prior art, referred to throughout this appeal and by Mr Dennehey as D2 and D9, disclose the use of pyrethrum and its constituent pyrethrins to remove sea lice from salmon. Pyrethrum and the pyrethrins within it are natural products derived from chrysanthemum plants. Mr Young advances the argument that the proper technical meaning of the word “pyrethroid” refers only to a class of chemicals which are synthetic analogues of the natural pyrethrins. For this reason he says that the claims of the patent must be taken to be limited to the use of these synthetic compounds whereas D2 and D9 disclose the use of natural pyrethrins and pyrethrum only.

This issue is considered at paragraphs 61 to 71 of the decision. Mr Dennehey refers to the evidence given by the witnesses as to the meaning of the word “pyrethroid” in the art. He recounts that the word is used by most workers to encompass both synthetic and natural chemicals although there are undoubtedly some who use it in a more limited way as referring to the synthetics alone. Further, he makes reference to 7 technical documents dated 1990 or earlier, each of which, he says, uses the word “pyrethroid” in a way which clearly encompasses both natural and synthetic compounds. Some refer to pyrethrins as “natural pyrethrins”, “natural pyrethroids” or just treat them as part of the group of compounds known as “pyrethroids”. They use the expression “synthetic pyrethroid” to designate synthetic compounds. In fact in this section of the decision it appears that he has made an error. It is likely that one of the documents he relied on, namely “Veterinary Applied Pharmacology & Therapeutics” by Bander, Pugh and Bywater was provided to him, as it was to me, in an inadequately photocopied form. One part of a page was not visible. When a proper copy was produced during the appeal it became clear that the authors had written:-

In this passage the term “pyrethroid” is used to refer only to synthetic compounds. Nevertheless, the documents taken as a whole support the evidence of the witnesses that most workers in the art use the term “pyrethroid” to cover both natural and synthetic compounds. As Mr Hacon points out, these documents show that amongst those who use the term in the wider sense is Dr M. Elliott who is regarded as one of the leading lights in the world of synthetic pyrethroids.

It follows that this word has a technical meaning which includes natural pyrethrins but that a minority of workers use it in a more restricted sense.

The next step is to consider how the term is used in the context of the patent. Mr Young argues that all the particular compounds referred to in the patent are synthetic, including all those in the table set out at paragraph 8 above. He says that the patentee must be taken to have intended to limit himself to synthetic chemicals. He says that there is no express reference to “synthetic” in the patent because there was no need to do so. It was implicit in the use of the word “pyrethroid”.

In my view Mr Dennehey was right to reject these arguments. The fact that all the pyrethroids mentioned in the patent happen to be synthetic does not indicate that the patentee intended to limit himself to synthetics. It leaves the matter unresolved. To the majority of readers, therefore, the use of the expression in the patent would have been taken to be a reference both to synthetic and natural compounds. If the patentee had intended to use the term in the less usual restrictive sense, he should have done so explicitly.

There is an additional reason why, in my view, Mr Dennehey’s decision is correct. As Mr Young accepts, there is nothing in the patent to suggest that the inventor thought, or had reason to suspect, that natural compounds would not work in the same way and just as well as synthetics. The passage in the specification set out at paragraph 8 above shows that the inventor did not know what the mechanism was which made his treatment works. The only suggestion that he makes is that the tolerance is due to the presence of seawater rather than freshwater. Nowhere in the evidence is it suggested that any reader would consider that, if this is the underlying reason for the success of the treatment, it would not apply just as readily to the use of natural pyrethrins. In other words there is nothing in the patent to suggest that the patentee believed that his treatment worked because the compounds he used were synthetic rather than natural. There is therefore nothing to suggest that the inventor intended to limit himself to synthetics. His invention would be thought to cover the synthetic and natural compounds.

One other major point is advanced by Mr Young in response to the attack of anticipation. He argues that although both D2 and D9 teach the use of pyrethrum to selectively kill sea lice on salmon, they do not anticipate because they do not describe anything which is sufficiently effective to fall within the meaning of the word “treatment” as used in the claims. Mr Hacon says that the reason why Mr Dennehey does not deal with this in his decision is that it was not argued before him.

Mr Young says that in the context of the patent “treatment” must mean effective to kill at least somewhere in the region of 95% of the sea lice. If so, neither of these pieces of prior art anticipate since they disclose kill rates of 74% and 89%.

In my view there is nothing in this point. The patent includes no suggestion that any particular level of efficacy is required. Furthermore it appears that there is only one example in the patent of anything which reaches or exceeds the level suggested by Mr Young, namely the use of tetramethrin at 8 ppm as recorded in the table set out at paragraph 7 above. All the others fall short, and in some cases far short, of the 95% level. Mr Young’s response is to say that none of these examples are within the claims. I find this a difficult argument to accept. Not only does the patent not indicate that the examples are outside the scope of the invention claimed, but all of the examples which involve use of pyrethroids do so at dosage levels well within the ranges selected as particularly inventive in the claims.

Mr Hacon is right when he argues that the procedure which removes, say, 74% of the sea lice parasite is a “treatment” of sea lice infestation and falls within the claim. Consistent with this is the view expressed by one of the expert witnesses, Professor Stenersen, that the experiments in D2 and D9 exhibited “remarkable success”. The fact that all the witnesses appear to have accepted that, at least by 2002, the sea lice kill levels described in these pieces of prior art were not sufficiently high to be commercially acceptable does not mean that they are outside the scope of the claims.

For these reasons, the appeal against the finding of anticipation fails.

Although Mr Dennehey found obviousness over three pieces of prior art, namely D1, D2 and D9, it is sufficient to consider the first of these. This document is the DSc thesis of a Dr Horsberg and his wife, Dr Tonje Høy. It refers to D2 and D9 which are publications produced by a team working at the Institute of Marine Research in Norway. Mr Young says that if D1 is a prior publication, it can and should be read together with D2 and D9. The contents of these three documents are considered fully in the decision under appeal. For present purposes it is convenient to set out their major disclosures. I shall deal with them chronologically.

This document is a published summary of a presentation given by Mr Jens Holm and Mr Per Jakobsen on 16 January 1990 as part of the 1990 Annual Meeting Seminar on Fish Health in Norway. As its title indicates, it reports what it claims are promising results obtained by using pyrethrum to kill salmon lice. It starts with a short description of existing treatment of these parasites and notes that radically new methods of treatment have not been found. It then says “We believe we have found the answer”. That is the use of natural pyrethrum. It is claimed that this substance is more effective and far preferable to current synthetic nerve toxins (which would include dichlorvos). On page 2 the following is said:

A test is then described which is said to demonstrate a significant effect of the pyrethrum on the sea lice. The authors describe pyrethrum as a very promising candidate as a pesticide for salmon lice and say that further tests will be carried out. They also praise the use of pyrethrum, not only because it is a natural product, but because it is environmentally friendly since it can be derived from plants grown in non-agricultural land in a developing country, Kenya, to the benefit of poor farmers there. It also states that

This is the published text of a presentation at the Irish Salmon Grower’s Association Annual Conference and Trade Exhibition given by the same Messrs Holm and Jakobsen together with Ms K. Blixen. The first page is an abstract. It contains a brief description of the problems caused by sea lice infestation in the sea pens used in salmon farming and then goes on to describe pyrethrum. The authors state that using this for treating fish “did not cause mortality in the salmon”. They then go on to say as follows:-

Pages 2 to 10 containing a more detailed description of the use of pyrethrum to combat sea lice infestation. On page 2, the authors state as follows:-

The authors go on to describe the two application methods alluded to in the abstract, namely the use of an oily surface layer containing the active ingredients and the “dipping” or “bath” method. Lice mortality rates of 88% are said to have been achieved with the first method and 89% with the latter. The Conclusion on page 10 includes the following:-

This thesis considers the nature of sea lice infestation and its impact on fish farming, the existing treatment and its defects and a number of potential alternative treatments. Five of the latter are mentioned. The last of these is introduced as follows:-

Having referred to the fact that pyrethrins are light and oxygen sensitive and therefore must be used with additional anti-oxidants, the authors continue:-

Against the background of this prior art, I can now consider the major arguments advanced by Mr Young. The first issue is whether D1 was published before the priority date of 18 March 1991. This is dealt with by Mr Dennehey at paragraphs 51 to 56 of the decision. The major point taken by Mr Young is that Dr Horsberg only distributed copies of his thesis to other people within his department prior to that date and that such disclosure should be treated as internal. Mr Young argues that had anyone from the department taken a copy of the thesis to a competitor on, say, 17 March 1991, it would have been considered a breach of duty to the department or to him.

This submission takes no account of the unchallenged evidence of Dr Horsberg that as soon as the thesis was returned from the printers on 27 February 1991, it was the intention to make it available to the public at large from that date and was treated as such. Amongst other things, this resulted in copies being sent to libraries before the priority date, although they were not proved to have actually been put on the public shelves by the receiving library before that date. No doubt a few days were taken for transit in the post and for the libraries to catalogue the thesis prior to public display. However on the facts of this case, the intention was to make the thesis available to the public as soon as reasonably possible after its return in final form from the printers. Consistent with this, Dr Horsberg gave the following evidence relating to how his thesis was treated in Norway:-

Copies of the thesis was sent to the Study Section of the Norwegian School of Veterinary Science on or before 4 March 1991. Dr Horsberg explained:-

Such limited oral evidence as was given in relation to this subject supports the view that the thesis was available for inspection by anyone before the priority date. It is therefore prior art.

The next major argument is that Mr Dennehey was in error in assessing who was the relevant addressee of the prior art for the purpose of an obviousness attack. Mr Young says that the addressee is a fish health expert alone. Although he accepts that Mr Dennehey’s precis of the law, including case law which confirms that the addressee may have the technical expertise of a team of workers from different disciplines, he says that Mr Dennehey was wrong in this case to conclude that the notional addressee had relevant expertise of both a fish health expert and a toxicologist. One of the reasons this plays a major part in Mr Young’s argument is that it is the precursor to an argument that the fish health expert would be put off use of pyrethrum and pyrethroids because of their known toxicity to salmon. Whereas a toxicologist might not be deterred, a fish health expert would, so he argues. In particular the latter would not realise that a dosage “window” might exist at which these agents would be too dilute to kill the fish but at high enough concentration to kill the lice.

In fact there is nothing in this latter argument because, not only was the existence of just such a window known for the existing treatment using dichlorvos, but D1 expressly identifies the existence of this in the passage concerning the “margin” of toxicity.

In any event, the argument relating to the characteristics of the addressee of the prior art also fails. Each of these documents propose the administration of poisons. In my view Mr Dennehey was correct to say that the relevant addressee would have both fish health expertise and toxicology expertise. In real life it would be a team. This can be looked at in two ways. D1 suggests that synthetic pyrethroids are probably the way forward. If this were read by a toxicologist, say someone in the employee of a company making such compounds, he would call in a fish health specialist consider the application of this class of compounds to fish. On the other hand, if the prior art were read by a fish health expert who was ignorant of pyrethroids toxicology, he would inevitably call in someone with that expertise. In either event one ends up with an addressee having both areas of expertise.

Mr Young also argues that the results set out in D1, D2 and D9 together are insufficiently good to justify further experimentation. This dovetails into his argument, referred to above, that the prior art produces results which are not sufficiently good to qualify as “treatments” of sea lice. I have already considered that. This more general argument also fails. The skilled worker reading this art, and particularly the passages set out above, would realise that the use of synthetics was highlighted as a probable way forward, that the initial tests were extremely encouraging and that further optimisation would be necessary. Professor Stenersen’s reaction referred to in paragraph 22 above is understandable and would be the reaction of the notional addressee. There is no reason to believe that such an addressee would reject the steer given by Dr Horsberg. The fact that there were other promising routes does not diminish the obviousness of trying this one.

Finally I must deal with claims 6, 8 and 9. As mentioned above, before Mr Dennehey, Vericore did not limit the number of claims for which it maintained independent validity. On the other hand it does not appear that it paid particular attention to any of them other than claim 1. Before me, Mr Young maintains that there is something special and inventive about using a suspension as the means of delivering the pesticide. Mr Hacon protests that this was never asserted in the evidence, argued before Mr Dennehey or foreshadowed in Mr Young’s skeleton argument. Even if these criticisms are correct, one must not lose sight of the fact that the onus of proving obviousness is on the respondents.

Mr Dennehey found that suspending pesticide in water was a standard way of using them. Mr Young does not challenge this. On the other hand he points to the fact that in prior art documents D2 and D9 an emulsion of pyrethrum was said to be toxic to fish, at least at the dosage levels there used. He argues that if an emulsion was toxic, a non-inventive skilled addressee would expect a suspension to be so. He puts forward an explanation for the relative toxicity of pyrethrum as follows. He says that one of the two methods of administration suggested in D2 involves the use of a pyrethrum-containing oil layer floating on the seawater. Salmon irritated by lice infestation jump more than non-affected salmon. They therefore jump through the oil layer. During this passage the lice and outer skin of the salmon are brought into contact with the pyrethrum but the inside of the gills are not. The salmon therefore do not absorb the pyrethrum through their gills. If an emulsion or suspension we used, the salmon would breathe the pyrethrum-containing seawater, would absorb the pyrethrum and would die.

There are a number of problems with this. I only need referred to two of them. First, the suggestion that the survival of the salmon can be attributed to lack of access by the pyrethrum to the inside of the gills is not supported or suggested by any of the evidence in the case. Second, it ignores the fact that the bath or dipping process described in the prior art, which gives the best results, cannot be explained on this basis. It seems to me that this argument is linked to Mr Young’s attempt to exclude toxicologist expertise from the notional addressee of the prior art. Once one embarks upon attempting to use synthetic pyrethroids as suggested in the prior art with the assistance of a toxicologist, it would have been obvious to at least try using the pesticide in a standard and simple way, namely as a suspension. There is nothing in this case which suggests that warnings about using pyrethrum in an emulsion at the levels indicated in the prior art would have deterred a toxicologist from trying a pyrethroid in suspension at the probably lower dosage levels he would choose. It should also be borne in mind that D9 ends with the suggestion that there should be investigation of easier methods of administration. In so doing, the document states the obvious. It follows that this response to the obviousness attack also fails.

For these reasons I will dismiss this appeal.