AN EXPERT SHOULD HAVE EXPERTISE IN THE ISSUE THEY ARE GIVING EVIDENCE ON: THEY CAN’T SIMPLY TEACH THEMSELVES FOR THE PURPOSE OF THE CASE

There are some important observations on expert evidence in the judgment of Mrs Justice Bacon in Sycurio Ltd v PCI-Pal PLC & Anor [2023] EWHC 2161 (Pat). An expert must give evidence within the scope of their expertise.  To assert expertise because they have read up on the issues for the purpose of the action is wholly insufficient.

“What the expert should not, however, do is to give evidence on the basis that they have sought to read in and educate themselves in the relevant field for the purposes of the case in question. A person does not become an expert by virtue of having acquired knowledge in the course of the case itself. Nor should an expert give evidence on a subject which falls outside their expertise, but which they consider they understand “well enough” to express a view on the matter. An expert is not instructed for court proceedings on the basis that they believe that they have “sufficient” grasp of the matter to express a view, or are able to teach themselves what they need to know in the course of preparing their evidence. They are instructed on the basis that they are a genuine expert in the relevant field, whose opinions may be relied upon and given weight by the court.”

THE CASE

The judge was giving judgment in an action relating to the alleged breach of a patent relating to the processing of telephone calls within a call centre. The claimant called two experts in support of its case. The first expert gave evidence that was appropriate and uncontroversial. However the second expert, whilst able to give evidence with the sphere of her own expertise, was not an expert on some of the technical issues.  The judge stated that this expert should not have been giving evidence on these matters.

THE JUDGMENT ON EXPERT EVIDENCE

Preliminary comments

8. Before commenting on the evidence of the expert witnesses for Sycurio and PCI-Pal, respectively, it is necessary to make some preliminary observations about the duties and responsibilities of expert witnesses in patent cases, and the corresponding obligations of the solicitors who assist those witnesses in preparing their evidence.

9. There is no dispute that an expert witness in a patent case is subject to the rules of CPR Pt 35. These include under r. 35.3(1) the duty of experts “to help the court on matters within their expertise”, and under r. 35.10(1) the requirement for an expert’s report to comply with Practice Direction 35.

10. Practice Direction 35 includes the following requirements:

“2.1   Expert evidence should be the independent product of the expert uninfluenced by the pressures of litigation.

2.2 Experts should assist the court by providing objective, unbiased opinions on matters within their expertise, and should not assume the role of an advocate.”

11. The starting point in both CPR Pt 35 and the accompanying Practice Direction is therefore that the expert witness must give evidence on matters which fall “within their expertise”. That may of course require the expert to do some further research to enhance their existing knowledge in the field, so as to be able to assist the court with the specific issues in the case. An expert may also wish to do background reading in relation to a related field in which they do not profess specific expertise, so as to be able to understand the context of the questions which they are asked which do fall within their field of expertise, and thereby to give useful answers to those questions.

12. What the expert should not, however, do is to give evidence on the basis that they have sought to read in and educate themselves in the relevant field for the purposes of the case in question. A person does not become an expert by virtue of having acquired knowledge in the course of the case itself. Nor should an expert give evidence on a subject which falls outside their expertise, but which they consider they understand “well enough” to express a view on the matter. An expert is not instructed for court proceedings on the basis that they believe that they have “sufficient” grasp of the matter to express a view, or are able to teach themselves what they need to know in the course of preparing their evidence. They are instructed on the basis that they are a genuine expert in the relevant field, whose opinions may be relied upon and given weight by the court.

    11. As to the process by which an expert report is prepared in a patent case, both parties agreed that the position was correctly set out by Arnold J in Medimmune v Novartis [2011] EWHC 1669 (Pat), §§99–114. In particular, both parties endorsed the propositions that the specialist nature of such cases and the likely fields of expertise of the expert witnesses instructed in such cases mean that expert witnesses in patent actions require a “high level of instruction by the lawyers”, and that in practice expert reports in patent cases are often drafted by the lawyers on the basis of what the expert has told them, with the expert then amending the draft report as appropriate (§110).

13. That process must not, however, obscure the duties of the expert as set out in CPR Pt 35 and Practice Direction 35. In particular it must not lead to an outcome where the expert strays into giving evidence on matters falling outside their expertise, on the basis that they have been asked questions by their solicitors which they have endeavoured to answer. That is an outcome which both the expert and their instructing legal team must be vigilant to avoid. The instructing solicitors should not simply assume that the expert will understand the requirements of CPR Pt 35 and the Practice Direction. It is their responsibility to ensure that the expert has the necessary expertise and is aware of the duties imposed on an expert witness.

14. With those preliminary comments in mind, I will comment on the parties’ expert witnesses. The evidence of those witnesses was divided up differently, reflecting a fundamental disagreement between the parties (which I will need to address below) as to the subject of the Patent and the characteristics of the skilled team to which it is primarily addressed.

The Claimant’s witnesses

16. Sycurio divided its evidence between Mrs Concepta Penn and Professor Kin Leung. Both of them were cross-examined.

17. Prof Leung specialises in telephony and networking. Since 2009 he has held the position of Head of the Communications and Signal Processing Group within the Electrical and Electronic Engineering department at Imperial College, London. His principal role was to explain to the court how traditional circuit switched and more modern packet switched internet-based telephony systems work, in order for the court to understand (in particular) the technology underlying PCI-Pal’s Agent Assist system. His expertise was unquestionable, and most of his evidence was uncontroversial.

18. Mrs Penn is a consultant specialising in payment card processing, including call centre payments, at an operational level. She has in-depth knowledge of the various international card scheme rules, and UK and EU card payment standards. In that field, her expertise was not in doubt. She does not claim to have any expertise in the technical solutions used to implement the card processing systems which she has worked on and designed, and she explained that for those purposes she would work together with engineers who would implement the system she had specified. Her evidence addressed the issues in the action as a whole, including the scope of the CGK, novelty and obviousness over the prior art, and infringement. She was therefore Sycurio’s main witness in the action, and she was cross-examined over almost two days. At the outset of her cross-examination, Mr Silverleaf noted that Mrs Penn was dyslexic and might on occasion need additional time to read documents.

19. During her cross-examination, it became apparent that Mrs Penn was struggling to understand and answer the questions put to her on the technical documents, in particular the Van Volkenburgh, Schaffer and Proctor patents and PCI-Pal’s Product and Process Description (PPD), despite having addressed all of these in considerable detail in her expert reports. Her answers became increasingly confused, and on several occasions she was unable to explain points that she had specifically commented on in her written evidence. Following discussion with Mr Silverleaf immediately after Mrs Penn’s oral evidence had concluded, and further discussion during the next day of the hearing, Mr Silverleaf recalled Mrs Penn (at my invitation) to explain her difficulties during her cross-examination and also the way in which her written evidence had been prepared.

20. When recalled, Mrs Penn gave evidence in chief (in response to questions from Ms Nezami) and was then cross-examined again by Mr Tritton. It is to Mrs Penn’s credit that she was willing to be recalled after what had clearly been a very difficult initial cross-examination, and the explanations which she went on to give were in my judgment entirely candid.

21. Mrs Penn started off by explaining that she had struggled in particular on the second day of the trial due to lack of sleep and a medical issue for which she was taking prescription medication. She had been dehydrated and had become increasingly unable to concentrate on the questions she was being asked. She said that her dyslexia meant that she had been unable to find relevant references in the documents she was being asked about, which had added to her stress.

22. I accept that these issues may well have impacted on the quality of Mrs Penn’s evidence (particularly on the second day of her cross-examination). The real problem, however, was that she was giving evidence about matters which fell well outside the scope of her expertise. That had been apparent from the first day of her cross-examination and continued throughout her oral evidence. It was confirmed by Mrs Penn’s description of the way in which her evidence had been prepared, in response to Mr Tritton’s further cross-examination. She explained that she had not written the first draft of her expert reports herself, but had sent copious notes to her instructing solicitors, who had then spent many months putting her reports together, with further input from her on specific points. She frankly admitted that she had struggled to understand PCI-Pal’s PPD and had spent many days and a “huge amount of research” to be able to do so. The Shaffer patent had been, she said, “an absolute nightmare” to try and understand, but she said that she had eventually got through it. She had done research on various other technical points to reach what she considered to be an adequate level of understanding to enable her to comment on them in her evidence. She maintained that the final written reports were entirely her own evidence, and that she had read them carefully and agreed with the points made. She said, however, that because her own language was so non-technical, the solicitors had sometimes reformulated what she said to put it into the right form of words.

23. Having considered Mrs Penn’s further evidence, Mr Tritton eschewed any submission that it had been prepared in an improper manner, as such. But Mrs Penn’s explanations highlighted the difficulties she faced in trying to address the issues in the case. She had sought – no doubt with the best intentions – to understand and educate herself on the telephony technology referred to in the prior art and the PPD. It was, however, not within her field of expertise and she should not have been giving evidence on those points. That should have been readily apparent to her instructing solicitors.

24. The result is that I am unable to accept Mrs Penn’s evidence on any matter that falls outside her core area of expertise. As to the matters which did fall within her expertise, namely payment card processing systems and the relevant industry requirements and standards applicable to those, her evidence was not controversial. The disputed matters in the case, in so far as they concerned the expert evidence, were matters on which Mrs Penn had opined, but for which I cannot give her evidence any weight.

25. That is no doubt why, in his closing submissions, Mr Silverleaf placed almost no reliance on Mrs Penn’s evidence. He contended that he did not need to do so, because he could make his points as legal submissions on the basis of the undisputed material and PCI-Pal’s own evidence. That was an unfortunate position to end up in, given the extensive scope of Mrs Penn’s written evidence. For the reasons set out below I consider that Mr Silverleaf’s submissions on the technical points could not be maintained without evidential support, which he ultimately did not have.