Related Sector: Expert Witness

It is an occupational certainty that expert witnesses will be challenged robustly in cross-examination; how the expert deals with that challenge will be revealing and will be commented on by the judge.

How should an expert respond to criticism, challenge, and adverse comment?

This article looks at the experience of two experts, Dr. E and Mr. T, in two very different cases. Both experts dealt with the challenge appropriately and their approaches are worth evaluating.

Expert Witness: Dr. E

Dr. E is a retired consultant paediatrician who was instructed by the prosecution in the recent murder trial of Lucy Letby.

During his cross examination, two paths were followed in order to try to undermine his credibility and reliability: the way in which he had become involved in the prosecution case and previous criticism of him by a judge in another case.

It was put to him, and Dr. E accepted, that he had contacted the National Crime Agency when he became aware that Cheshire police were investigating the infant mortality rate at the Countess of Chester Hospital, saying that he had expertise in neonatal cases and would be interested to help.

The defence accused him of “touting” for the role of expert witness for the prosecution.

In evidence, he stated that he was simply offering his professional opinion to the police should they need it. He said that he was fully independent and impartial, that he knew his duty to the court and was fulfilling that duty. When challenged that he had adopted a partisan approach, he went further by saying:

“I’m completely independent. I have been giving evidence in court for a long time. I know about impartiality. I know about the rules. I’m not here for the prosecution. I’m not here for the defence. I’m here for the court.”

He was also faced with the comments of a judge in the Court of Appeal in an unrelated case, who had criticised Dr. E for producing a report which the judge described as not providing a “balanced opinion”.

The defence used the above issues to argue that the judge should exclude Dr. E’s evidence from the jury on the grounds that he failed to act  appropriately, with independence, impartiality and objectivity.

The trial judge, Mr. Justice Goss, rejected that argument, on the basis that it was for the jury to consider the issue of Dr. E’s reliability by reference to all the evidence in the case.

Dr. E clearly did not accept that challenge made by the defence and stood by his assertion of independence. Although we will never know how the jury arrived at their decision to convict, it is a fair assumption to make that, in doing so, they accepted Dr. E’s evidence and must have found him to be a reliable witness.

Dr. E’s approach? Robust defence.

Expert Witness: Mr. T

Mr. T is another very experienced expert witness. A Chartered Surveyor of many years standing, he had been commended in 2014 by a judge in the Central Family Court for approaching a complex valuation with the “required degree of expertise and independence” expected of an expert witness.

In 2019, he was criticised in the Upper Tribunal (Lands Chamber) for not having inspected the objectors’ properties and, therefore, not being able to give a properly evidenced opinion.

He accepted the criticism made by the Deputy President of the Tribunal− that he should have applied to the tribunal when his solicitors refused to allow him the time to inspect the properties. He understood that he should not have allowed his instructing solicitors to limit his ability to fulfil his overriding duty to the court.

His evidence was not given much value by the judge in his judgment.

That was a stinging criticism, but one which Mr. T had to, and quite rightly did, accept. Mr. T went further when writing his next report for a new and unrelated case. He drew the court’s attention to the criticism made in the 2019 case, giving the case reference and the paragraph number in the judgment. He openly admitted where he had been at fault and went on to describe how he had gone back to the expression of the duty to the court in CPR35. He also made sure, in the instant case, that he was properly complying with his duty to the court.

Result? The Tribunal in the second case found him to be a credible, reliable witness with whom they agreed.

Mr. T’s approach? Transparent admission of fault.

What can expert witnesses learn?

There should never be any substitute for honesty and integrity. An expert must know the scope of their role and their duty and be able to express and demonstrate that they are fulfilling it at all times in their work as experts.

Criticism and challenge will come.

If it is well founded (i.e. if the expert has erred or not done something which they should have done), the expert must immediately accept that and not try to defend the indefensible. The longer they fight the point, the more their credibility will be destroyed.

This applies to future cases too. If the expert is proactive and transparent about any past errors, the scope for further cross-examination will be reduced. For example, in Mr. T’s case, he was cross examined about the error in the previous case – until the judge intervened and told the barrister to move on.

The expert should then go on to demonstrate what they have done to correct past mistakes and how they have guarded against a repetition in the future.

If the criticisms are not well founded, then the expert should say so. This is not about admitting fault where there is none.


Bond Solon urges experts in all disciplines to make themselves fully aware of their role and their duty under the rules of court. The duty to help the court and to be independent applies in all the UK jurisdictions whether through case law or through the rules of court in England and Wales. An expert witness must read, understand the rules and apply them.

Bond Solon’s expert witness courses always reference the duty of the expert.  The trainers are ready to discuss the application of that duty and the challenges that the expert will face as they seek to do so.

In reflecting on his experiences, Mr. T was well aware that whilst he had taken fifty years to build his reputation, that reputation could be destroyed in less than 50 seconds.

Author: Nicholas Deal 

This article was first published on 29 September 2023

Please leave a comment

  • Consultant Forensic Psychiatrist

    02 Oct 2023 14:09

    A valuable lesson for us all, Integrity is everything.

  • Ian Clark - Aviation Consultant

    02 Oct 2023 14:24

    I found this article to be very helpful and a reassuring reminder that honesty and transparency are principles to always uphold. Referencing previous cases and levels of criticism received is smart and not something I had previously considered - thank you.

  • Anonymous

    02 Oct 2023 15:23



    02 Oct 2023 16:32

    I had an experience in a criminal case at Manchester Crown Court that involved my writing a number of expert witness reports on fitted kitchens throughout the UK. While my evidence was being tested under quite aggressive cross examination, I realised that I had made a mistake in not properly investigating what is known as the clear air space above a gas hob in one of the kitchens, and that my written evidence was flawed, although the defence team did not pick up on the mistake at the time. This was on a Friday afternoon. I went home to the Scottish Borders and spent the Saturday properly investigating the issue, and drafting a memo to correct the evidence, which I sent to my clients, National Trading Standards, so they had it for first thing on Monday. When the case resumed on Monday. it was the first matter to be dealt with. I found out later that my openness with the issue went a long way to establish the whole of my evidence (which involved 15 days in the witness box!) as totally credible. So yes, transparent admission of a fault, even though in this case the fault had not been uncovered by the defence, but might have been later, can significantly enhance an experts credibility. As a PS if anyone is interested, the case lasted 9 months, cost millions of pounds, involved a mass of fraud and money laundering, as well as consumer issues (my bit), and at the end of the day, the jury could not get their heads round the financial issues and let the defendants off, but found the 6 defendants guilty on the consumer charges. They all went to prison. As a final PS, may I add that my Bond Solon training proved absolutely invaluable!

  • Kathy Priday - Radiographer and Expert Witness

    03 Oct 2023 12:37

    Another excellent article reminding us what to and what not to do. Thank you

  • Emil Mihaylov - Associate Specialist in Forensic Psychiatry

    03 Oct 2023 12:50

    Very helpful

  • Charles CLAOUE - Head of Chambers - EYE-LAW CHAMBERS

    03 Oct 2023 17:09

    The latter case is pertient in showing how some solicitors / agencies try to manipulate Experts as an attempt to control costs and pay Experts as little as possible. This is why some reports have to be titled "time-limited" so that the Court understands that the Expert has been limited in some way. If we feel that further examinations would be beneficial but we are unable to undertake them because of the solitor refusing to pay, this should be in report in plain English!

  • Clinical psychologist

    04 Oct 2023 02:23

    A helpful article

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