Expert witness statements. Too many cooks?

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Joint statements are not a group activity: Mark Solon warns against improper influence on an expert’s opinion.

What happens if an expert’s draft joint statement after discussions with other experts is influenced by another party, such as a member of the legal team? The recent case of Pickett v Balkind [2022] EWHC 2226 (TCC) involved an expert witness who opened himself up to cross-examination at trial after it emerged in a pre-trial application that he had sent a draft of the joint statement to counsel, and had received comments back for consideration and inclusion in the final version.

What was the background?

The case was a first-instance decision in the Technology and Construction Court (TCC) of Judge Paul Matthews. The matter involved a tree subsidence claim, involving expert witnesses in a number of areas, including structural engineering and arboriculture.

One of the claimant’s experts anticipated being unable to attend trial because of a surgical appointment and  the subsequent recovery period. The claimant’s solicitors sent the defendant’s solicitors a draft application to request a different date. In support of the application was a letter from the expert witness, which set out the need for surgery but also included the following: ‘I have been through Daniel’s comments on the Joint Statement and have made just a couple of minor changes where I was unable to be as definite as his wording. Attached is a word doc for your/Daniel’s comment.’

Daniel, as the judge drily pointed out, was counsel instructed by the claimant.

Why was this a breach?

The defendant’s solicitors rightly sought to raise their concern that the claimant’s barrister had improperly been involved in the formation of the joint statement. The arguments about disclosure and privilege  need not concern us here, but the key point is the involvement of the claimant’s lawyers in the joint statement. On that point, the judge referred to CPR 35 and to the additional comment given in the TCC Guide (at para 13.6.3 of the Guide):

‘Whilst the parties’ legal advisors may assist in identifying issues which the statement should address, those legal advisors must not be involved in either negotiating or drafting the experts’ joint statement. Legal advisors should only invite the experts to consider amending any draft joint statement in exceptional circumstances where there are serious concerns that the court may misunderstand or be misled by the terms
of that joint statement. Any such concerns should be raised with all experts involved in the joint statement.’

Given the clear evidence that there had been comments from counsel on the joint statement, the judge held that it was entirely appropriate for the expert witness to be cross-examined at trial on those comments. It was appropriate to challenge the experton the nature of these comments, as well as whether or not he had incorporated them. In reaching his decision, HHJ Matthews referred to the case of BDW Trading Ltd v Integral Geotechnique (Wales) Ltd [2018] EWHC 1915 (TCC), [2018] All ER (D) 193 (Jul) where, at para [18], the judge in that case described it as a ‘serious transgression’ for an expert witness to provide the instructing lawyers with a draft of the joint statement  for their comments. It sounds basic, but the duty of the expert is to the court and not the paying party. The opinion must not be influenced by the lawyers and be seen not to be influenced.

No excuses

The current case is not making a new point; rather, it is the latest in a growing list of authorities, all saying the same thing: the joint statement must be drafted, agreed, and signed by the experts in the discussion and nobody else. Only once in its final form can it be sent to the instructing solicitors. Given that CPR 35 is so clear on this point, why does the rule continue to

be breached? It is impossible to state why some lawyers are making comments on the joint statement when it is a clear breach of the rules for them to do so. Ignorance of the law is no excuse. Expert witnesses who find themselves complicit in such a breach risk their reputation and credibility, as they may find themselves criticised, by name, in the judgment.

The only way for an expert witness to be confident of avoiding the same fate as the expert in this matter is to ensure they know and understand their duties and obligations, without having to rely on lawyers to inform them. An expert witness who has a thorough knowledge and understanding of their duties under CPR 35 (CrimPR 19 for those in the criminal justice system and FPR 25 for those in the Family Court) will be able to identify when they are being asked to do something which breaches the rules of court.

To help expert witnesses carry out their work in compliance with the rules, Bond Solon offers a variety of courses, such as Discussions Between Experts, Excellent in Report Writing and Law & Procedure (civil, criminal, and family law options): see

Lessons for lawyers

Always remember that although you instruct and pay for an expert’s opinion, the duty of that expert is to the court, not to you or your client. Discussions between experts are exactly that, and lawyers should not interfere with the joint statement made by the experts setting out where they stand on the issues.

Lawyers should immediately guide an expert who may fall foul of the relevant court rules and not assume the expert is fully conversant with those rules. Finally, they must avoid the classic mistake of not fully checking any documentation that is sent to the other side.

Author: Mark Solon

Article first published: 28 Otober 2022

Article published in: New Law Journal (