The question of whether an expert witness can be supervised or mentored is sometimes raised in our training courses. What level of input can an expert witness safely seek?
Re-active vs pro-active
First, it is essential to distinguish between re-active and pro-active input. Pro-active attempts by an expert witness to enhance and expand their expertise – to familiarise themselves with the role and duties of the expert witness and to understand the procedural rules and their application – are to be encouraged. Indeed, for healthcare professionals there is unequivocal guidance that training as an expert witness be undertaken.
Re-active input, on the other hand, arises on a case-by-case basis; in other words, it is initiated because the expert witness has been instructed in a case and they are now seeking some form of input.
In broad terms, the courts are very much in favour of pro-active input and very much against re-active input.
In terms of input that an expert witness might look for, there is a sliding scale ranging from collegiate advice (from fellow experts in the field), through to mentoring (encouraging career development and learning) to supervision (overseeing the work of another).
Turning to the caselaw, let’s see what the courts have said. While there is little case law directly on this subject, there are well-established principles to be applied.
Collegiate advice
The approach of the English and Welsh courts is pragmatic. The main issue is that the expert witness must have the requisite expertise themselves, rather than being “a quack, a charlatan or an enthusiastic amateur” (Bingham LJ, R v Robb [1991] Cr App R 161).
The courts will not prescribe how the expert should gain that expertise (Lord Russell of Killowen, Silverlock [1894]2 QB 771), approved by Bingham LJ in Robb); they are only concerned to know that the expert does indeed have it.
The courts also recognise that an expert is entitled to research an issue in order to arrive at an opinion, provided that their research is in order to enhance an expertise they already have, rather than to become an expert in an area where they have no knowledge at all. The expert needs to keep a record of the sources they have used, whether they be the literature or the views of colleagues (trial judge in R v Contogoulas & Reich, quoted with approval by Gross LJ in R v Pabon, [2018] EWCA Crim 420); the court must be told how the expert has arrived at their opinion.
Supervision
The issue arose directly in the case of Pinkus v Direct Line Group Ltd [2018] WL 00660352. Both parties had instructed expert neuropsychologists to examine the claimant; following a discussion between the experts, it became clear that the claimant’s expert, Dr Pierce, had been seeking input from a supervisor before completing the joint statement.
At a pre-trial directions hearing, the judge ordered that cross examination of Dr Pierce be allowed at trial on the nature and extent of the input from her supervisor.
The judge questioned what the purpose of supervision was. If it is to “assist with, supervise or review the content of an expert report” then that should be made clear in the report itself. The judge went on to observe: “Any expert who discusses the content of a proposed report in detail with another expert under a peer review arrangement must be extremely cautious if he or she thinks it is not appropriate to disclose the fact and extent of that arrangement.” (HHJ Cotter QC, at para. 39)
Mentoring
The cases do not deal directly with the issue of mentoring. Some principles are clearly applicable, however:
(i) the expert must themselves have the required expertise;
(ii) the expert owes the duty to the court;
(iii) they must express their own opinion, on matters within their own expertise;
(iv) they must keep records of any research they do and of the sources they use, so that the court and the other party know how they have arrived at their opinion;
(v) a supervisory relationship should be disclosed in the report.
Any mentoring relationship should avoid discussion of the evidence in a particular case and be confined to offering encouragement, support and advice on the role of being an expert witness and progressing through a career as an expert witness. A mentor who did discuss the evidence with their mentee could well find themselves being cross examined about their discussions.
Conclusion
So, if you are considering any form of input into your expert witness career, ask yourself this: is this pro-active (general training) or re-active (initiated because of the case)? If the latter, don’t get into any discussion about the evidence – the courts would not approve.
Author: Nick Deal, Barrister and Bond Solon Expert Witness Trainer, August 2021.