Other blogs will discuss this case on a variety of grounds, but PatLit focuses on just one thing: the very helpful summary of the duties of the expert witness as they are applied to patent litigation. Said the judge, at paragraphs 109 to 114:
"109. Expert witnesses in patent litigation stand in a rather unusual position. They are generally leading scientists or engineers in the field in question. Frequently they are academics. Sometimes they are consultants. In most cases, they will not have given expert evidence in patent litigation before, although there are exceptions to this [Presumably those who fail are discarded; those who succeed may not be needed again]. Not only that, but also they will generally have little experience of the patent system. Where do they have experience, it will generally be as inventors named on patents. As such, they may have had scientific input, but generally they will have learnt little about patent law in the process. In some fields, they may also be accustomed to using patents and patent applications as sources of technical information, but again without necessarily understanding much about patents themselves. When asked to prepare an expert report in a patent case, they will have to consider such questions as the identity and attributes of the person skilled in the art to whom the patent is addressed, the common general knowledge of the skilled person and whether something would or would not be obvious to that person in the light of particular prior art given the constraints imposed by the law of obviousness. Usually, this is not a task of which they will have any previous experience [The task is made more difficult by the fact that they are being to describe the characteristics of an individual or team which may be strongly shaped by evolving judicial guidance which they may not fully appreciate].
110. For these reasons expert witnesses in patent actions require a high level of instruction by the lawyers. Furthermore, even if they are experienced authors, they need considerable assistance from the lawyers in drafting their report. In practice, most expert reports in patent cases are drafted by the lawyers on the basis of what the expert has told them and the draft is then amended by the expert. This, of course, requires the lawyers to understand what the expert is saying. It follows that the drafting of an expert’s report in a patent action involves a steep learning curve for both the expert and the lawyers. The lawyers are learning the technology and the expert is learning enough of the law to understand the questions he must address [Good point]. It follows that a high degree of consultation between the expert and the lawyers is required. Frequently, the preparation of the report will involve an iterative process through a number of drafts.
111. It is obvious that this process entails a risk of loss of objectivity on the part of the expert even if the expert is striving to remain independent and impartial. It is therefore crucial that the lawyers involved should keep the expert’s need to remain objective at the forefront of their minds at all times [a counsel of perfection?]. If they cause or allow the expert to lose his objectivity, they are doing both the expert and their client a disservice. They are doing the expert a disservice because he may be subject to criticism during cross-examination and in the court’s judgment as a result. They are doing the client a disservice because partisan expert evidence is almost always exposed as such in cross-examination, which is likely to reduce, if not eliminate, the value of the evidence to the client’s case [the ritual of cross-examination with a view to exposure may be difficult to eliminate, since it runs deep in the psyche of the lawyer'expert relationship, whether in IP or beyond it].
112. I will illustrate this point by reference to two common traps for the unwary. The first lies in discussing the prior art. The expert will generally be asked by the party instructing him to express an opinion as to whether taking a particular step would or would not have been obvious to the skilled person at the relevant date in the light of certain prior art. Suppose the instructing party contends that the step would be obvious. The lawyers show the expert the prior art after having carefully explained to him the correct approach to this question, and ask him for his opinion. The expert expresses his genuine, independent and impartial opinion that taking the step would indeed have been obvious. Then the lawyers assist the expert to draft a report expressing that opinion. When drafting such a report, there is a natural tendency to focus on the parts of the prior art document which support the opinion which the expert holds. It is often the case, however, that there are parts of the document which point the other way or might be thought to point the other way or are equivocal. (Otherwise, it is unlikely that there will be a dispute.) It is important that the lawyers bring home to the expert the need to give a balanced account of the document in his report. The expert may think, for example, that such a passage is ambiguous and therefore best ignored; but if those instructing him allow him to pass over that passage in silence in his report, the inevitable consequence is that he will be confronted with that passage in cross-examination, asked why he did not mention in his report and accused of failing in his duty to the court.
113. The second example arises out of the fact that it is not uncommon for an expert witness to have some involvement with the invention in issue, or a similar invention, in the past. For example, he may have published a paper commenting on the invention or have been a named inventor on a patent application claiming a similar invention filed before or after the one in suit or he may even have given evidence in some form (such as a declaration filed with a patent office). The lawyers who are instructing the expert should make sure that the expert discloses such contributions and, where appropriate, explains them in his report. I am not suggesting that it is incumbent on the expert to carry out a search for such documents, merely that the expert should reveal what he is aware of. It should be brought home to the expert that the lawyers for the opposing party are likely to comb through his published papers and other publicly accessible records (such as patent office files); and that, if they find something relevant that has not been disclosed by the expert in his report, then the expert may be accused in cross-examination of failing in his duty to the court if it appears to favour the opposing party. If this is not made clear to the expert by those instructing him, then the expert may find himself in an uncomfortable position even though he had thought he was complying with his duty to the court (e.g. because he thought at the time of preparing the report that the material was not significant).
114. The law reports are littered with cases, including some patent cases, in which judges have criticised expert witnesses for failing to be objective or in other ways. It is regrettably true that from time to time an expert witness does succumb to the temptation of giving partisan evidence, and that is clearly unacceptable. But I wish to emphasise that the lawyers who instruct expert witnesses bear a heavy responsibility for ensuring that an expert witness is not put in a position where he can be made to appear to have failed in his duty to the court even though he conscientiously believes that he has complied with that duty [and woe betide the next counsel to appear before Arnold J and have this passage quoted back at him when he has led the expert to appear partisan]. It is also important that courts should be cautious about criticising an expert witness purely on the basis of omissions from his report unless it is clear that the fault lies with the expert rather than those instructing him, bearing in mind that the court will not usually be privy to the expert’s full instructions ...".This seems very sensible and PatLit is sure that the other Patents Court judges agree.