The court expert and conflicts of interest

It is unlikely that much time is spent thinking about conflict of interest when instructing medical experts to give evidence in court. Recent court decisions however are a reminder of the importance of addressing whether an expert has a conflict of interest and the importance of doing so both for the expert and the instructing lawyer.

CPR 35 provides little on this topic. CPR 35.3 (1) states only that “it is the duty of experts to help the courts on matters within their expertise.”  A conflicted expert cannot of course help the court.

35PD goes a little further.

2.1 provides that “expert evidence should be the independent product of the expert and influenced by the pressures of litigation“.

2.2 goes a little further in providing that “experts should assist the court by providing objective, unbiased opinions…“.

It is however in the Guidance for the Instruction of Experts in Civil Claims that the expression “conflict of interest“ is first mentioned.

The appointment of experts

16 Before experts are instructed or the court’s permission to appoint named experts is sought, it should be established whether the experts:

e. have no potential conflict of interest.

23 They should also inform those instructing them (whether on initial instruction or at any later stage) without delay if:

d. the instructions and/or work have, for any reason, placed them in conflict with their duties as an expert…

The experts’ declaration, as set out in 35PD 3.2 states that an expert’s report must contain a statement that the expert

a) understands their duty to the court and has complied with that duty; and

b) is aware of the requirements of part 35, this practice direction and the Guidance for the Instruction of Experts in Civil Claims 2014

Therefore an expert report properly completed, whilst not stating that the expert has no potential conflict of interest, will include a statement by the expert that he is aware that it should be established whether he has any potential conflict of interest.

In clinical negligence claims in the High Court it is interesting to note that the standard directions state that:

Experts shall, at the time of producing their reports, produce a CV giving details of any employment or activity which raises a possible conflict of interest.

What is a conflict of interest?

A conflict-of-interest (or, perhaps more accurately, a conflict of interests) will arise when an expert witness’s opinions are either (1) actually influenced, or (2) capable of being influenced, by his personal interests. The former state is obviously rare and where done consciously involves considerable moral turpitude. The latter state is more common and involves no wrongdoing.“ (Bux v GMC [2020] 1EWHC 762 Mostyn J)

An example of an actual conflict of interest, therefore, would be giving evidence in favour of a litigant with whom the expert is in a relationship. In contrast, the appearance of a conflict of interest would arise where that relationship ended years earlier, leading to the need to investigate whether the expert was actually conflicted.

Professional guidance

Professional bodies will generally have their own rules about conflicts of interest. In the GMC‘s Guidance on Acting as a Witness in Legal Proceedings at paragraph 23 it is stated:

If there is a possible conflict of interest – for example, you have been professionally or personally involved with one of the people involved in the case in the past, or you have a personal interest in the case – you must follow our guidance on conflicts of interest. You must also make sure the people instructing you, the other party and the judge are made aware of this without delay. You may continue to act as an expert witness only if the court decides a conflict of interest will not affect the case.

The GMC‘s Guidance on Conflicts of Interest relates to clinical rather than expert practice but nonetheless is useful.  

12 You should:

a) use your professional judgement to identify when conflicts of interest arise

b) avoid conflicts of interest where possible

c) declare any conflict to anyone affected, formally and as early as possible, in line with the policies of your employer or the organisation contracting your services

d) get advice about the implications of any potential conflict of interest [and] make sure that the conflict does not affect your decisions about patient care.

13 if you are in doubt about whether there is a conflict of interest, act as though there is.

Bux v GMC [2021] EWHC 762

Dr Bux accepted instructions to prepare medicolegal reports in respect of holiday sickness claims from a firm of solicitors in which his wife was a partner. He did so on what was described by the judge as “an industrial scale“ earning £123,000 in fees from 684 cases in under two years, the fees being paid into a company in which he and his wife were the shareholders. He was paid for the reports regardless of the outcome of the case and so had no financial interest in the litigation process beyond a reasonable expectation that he would be paid for any professionally prepared part 35 compliant reports that he provided. His wife was a salaried partner receive no bonus dependent on the outcome of her cases. Nonetheless it was held that this raised serious doubts as to the independence of the expert’s reports.

While it was not a case of actual conflict of interest, Dr Bux acted in a state of conflict of interest. The failure to disclose the relationship between Dr and Mrs Bux:

was sufficient to entitle any defendant, or its insurer, to query the transparency and objectivity of the process whereby the reports are produced. It raises at the very least a legitimate concern that the production of the reports may be driven by less than an objective and properly considered process.

Any such suspicion is likely to be fortified by the formulaic nature of the reports themselves, the virtual absence of any expert analysis, and the wholesale failure to comply with Part 35 and the relevant Practice Direction.’

In other words there was a real risk of a conflict-of-interest and it had to be disclosed. No disclosure was made and therefore, taking into account these matters and a number of other failings including in the reports, the striking off from the register of Dr Bux was upheld by the High Court.

EXP v Barker [2015] EWHC 38

The court deprecated a medical expert in this case who, it transpired (in the course of cross-examination) had worked for a considerable time with the party in his favour he was giving evidence and who the expert regarded as having “guided and inspired his practice“. Worse still it was the party who had recommended the instruction of the medical expert, whom he knew well, to act on his behalf.

The loss of independence and the conflict of interest which could well arise in this situation, and most certainly the appearance of a loss of independence or conflict of interest, fatally damaged the credibility of the expert in the litigation. Although the report was admitted in evidence by the court, it was in fact disregarded for these reasons.

Secretariat v A Company [2021] EWCA Civ 6

In this case an international consulting firm provided expert witness services for opposing sides in two separate but closely related international construction arbitrations, in one acting for A Company in a claim brought by a subcontractor and in the other acting for a project manager in a claim against A Company. The expert was a different entity in each case although within the same group of corporate entities. The court granted an injunction preventing the expert in the second claim acting against A Company for whom the related expert entity already acted.

The court avoided deciding whether it can be implied in law that an expert has a fiduciary duty owed to the party from whom it initially took instructions which prevented it from getting into a situation where a potential conflict of interest could arise. Instead, the case was decided on the express terms of the retainer between the expert and the company, which was construed to prohibit conflicts of interest throughout the duration of the engagement as expert. The two experts, although different entities, could possibly find themselves supporting opposing positions on the same or substantially similar issues.

The court in this case also stressed that the existence of conflict of interest is a matter of degree and the courts observation in the present case should not be taken as concluding that the same expert cannot act both for and against the same client in relation to a different project.

From these cases one can conclude as follows

  • The existence of a conflict of interest by an expert does not necessarily disqualify him, or render his evidence inadmissible, or of no weight. (EXP v Barker_
  • It is desirable that an expert should have no actual or apparent interest in the outcome of the proceedings in which he gives evidence but such disinterest is not automatically a precondition to the admissibility of his is evidence (Factortame (No 8) [2002] 3WLR 1104
  • But failure to disclose a potential conflict of interest can be a serious breach of professional rules (Bux v GMC).


1. Although there is no express rule to that affect, an expert witness has a legal duty to disclose to those instructing him, and the court, a potential conflict of interest, that is, all facts and matters which might reasonably suggest a conflict of interest

2. An expert must not leave undisclosed any conflict of interest which might bring into question the suitability of their evidence as a basis for the court’s decision

3. Disclosure must be made promptly, preferably on instruction, but certainly when facts giving rise to a potential conflict of interest become apparent

4. It is important to disclose the facts if only to explain why there is in fact no conflict of interest

5. A failure to comply with the duty of disclosure is like to have very serious consequences, both within the litigation and professionally

6. The terms of engagement of an expert should address this issue by including a term such as “the expert confirms that they are not conflicted to act as an independent expert in this matter”.

[Who or what is medico-legal minder?  Terms and conditions apply]