Judge Highlights Expert Witness Requirements

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On 20 July 2018, the Claimant, a former soldier, commenced proceedings against the Ministry of Defence, seeking damages for personal injury arising out of an alleged Non-Freezing Cold Injury (NFCI).

It was admitted by the Defendant that if the Claimant’s claim was found to be genuine then there was a breach of duty. But if the injury was deliberately engineered to make a fraudulent PI claim or if the Claimant had knowingly significantly exaggerated his NFCI symptoms to such an extent that he had been fundamentally dishonest, then the claim must be dismissed.

The case therefore turned on whether the Claimant had been honest about the existence, causation, and extent of the NFCI symptoms.

There were ten expert witnesses in total - five called by the Claimant and five called by the Defendant, with expertise in neurology, psychology, chronic pain, care therapy and employment. 

Expert Witness conduct

In the expert evidence section of his judgment, Mr Justice Cotter expressed criticism of the claimant’s care and employment experts who ‘acted at times as advocate for the claimant’ and ‘at times adopted the twin roles of expert and Judge of the facts’ therefore completely disregarding their duties as independent experts.

Given the issues with the expert evidence in this case, Mr Justice Cotter thought it necessary to provide a reminder of the expert witness role, stating that:

’experts should constantly remind themselves through the litigation process that they are not part of the Claimant’s or Defendant’s “team” with their role being the securing and maximising, or avoiding or minimising, a claim for damages. Although experts always owe a duty to exercise reasonable skill and care to those instructing them, and to comply with any relevant professional code, as CPR 35.3 expressly states they have, at all times, an overriding duty to help the Court on matters within their expertise. That they have a particular expertise and the court and parties do not (save in some professional negligence claims) mean that significant reliance may be placed on their analysis which must be objective and non-partisan if a just outcome is to be achieved in the litigation.’’

Mr Justice Cotter also referred to the well-known principles arising out of Mr Justice Cresswell’s judgment in National Justice Compania Naviera SA Prudential Assurance Co Ltd (”the Ikarian Reefer”) [1993] 2 Lloyd’s Rep 68 that every expert must adhere to at all times:

       i.         Expert evidence presented to the court should be, and should be seen to be, the independent product of the expert uninfluenced as to form or content by the exigencies of litigation.

     ii.         An expert witness should provide independent assistance to the court by way of objective unbiased opinion in relation to matters within his expertise. An expert witness in the High Court should never assume the role of an advocate.

    iii.         An expert witness should state the facts or assumption upon which his opinion is based. He should not omit to consider the material facts which could detract from his concluded opinion.

    iv.         An expert witness should make it clear when a particular question or issue falls outside his expertise.

      v.         If an expert’s opinion is not properly researched because he considers insufficient data is available, then this must be stated with an indication that the opinion is no more than a provisional one. In cases where an expert witness who has prepared a report could not assert that the report contained the truth, the whole truth and nothing but the truth without some qualification, that qualification should be stated in the report.

    vi.         If after exchanging reports an expert witness changes his view on a material matter having read the other side’s expert report or for any other reason, such change of view should be communicated (through legal representatives) to the other side without delay and when appropriate to the court.”

On compiling a report, Mr Justice Cotter brought attention to CPR 35 PD 2.3. This provides that expert should consider all material facts, including those that might detract from their opinions and CPR 35 PD 3.6(6), which refers to the need to deal with any range of opinions on the matters covered within the report. To avoid any finding of bias or prejudice, ‘’the court should receive a comprehensive, objective analysis; including whether an alternative view to that held by the author is tenable. An expert must not solely pick out pieces of evidence or entries in documents which provide support for the conclusion he/she has reached whilst not addressing material that points, or may point, the other way. Where there is a contrary interpretation, analysis or view it should be set out in the report and it is a breach of the duties owed to the Court by an expert to leave such issues to be raised by an expert instructed by the other party.’’

Finally, under CPR 35 PD 2.5, an expert should not ordinarily be criticised for changing his or her opinion in a trial, if matters have occurred after they have prepared a written report. However, in accordance with point 5 of the Ikarian Reefer principles, the expert should ensure that they communicate their change of opinion to the other side (through legal representatives) ‘’without delay and when appropriate to the court’’.  An expert must not step into a witness box having changed his or her view without having made all relevant parties aware beforehand.


This case serves as a timely reminder of the obligations and requirements that the courts place on experts, which all experts should regularly remind themselves of particularly before taking on any instruction and appearing to give evidence in court. If they are unsure of what is required of them, experts should consult their instructing solicitors and refresh their knowledge with training.

To help expert witnesses carry out their work in compliance with the rules, Bond Solon offers a variety of courses, such as Discussions Between ExpertsExcellence in Report Writing and Law & Procedure (civil, criminal, and family law options). Please visit here to view our full suite of courses.   

Author: Meera Shah, Content Manager

This article was first published on 1 December 2022