The Claimant asserted that the Defendant had infringed their patent for an electric shower-waster pump and control unit. The trial related to liability only. Both sides criticised the other’s expert. The Judge rejected these criticisms noting that, while he reached conclusions that differed from the experts in various places, he did not consider either expert to be unreliable or that their evidence generally should be discounted.

Catherine Jago is an oil and commodities Expert Witness with nearly four decades of experience in the field. She started her career at BP before working as an oil journalist, broker and trader. In 2023 she founded her own international Expert Witness practice, CJH Experts, which carries between 20 and 30 live instructions at any one time. Here, she tells us how she came to the role in unexpected circumstances, what makes a truly good Expert, and why independence is never negotiable.

The Claimant was suing in relation to profound disabilities he suffered due to the Defendant’s admitted clinical negligence. While some of the experts were praised, some were severally criticised by the judge, particularly for failing to consider the range of opinion. Two of the experts were also significantly hampered by their nervousness in cross-examination. 

JBX v Frimley Health NHS Foundation Trust [2026] EWHC 2294 (KB)

The EWI held the annual Scottish Medicolegal Conference at the Grand Central Hotel in Glasgow on 18 September. The event featured great speakers and panels and lots of interaction with the audience of expert witnesses and legal professionals.

Laura Langley, 38, was alleged to have killed her seven-week-old daughter Edith who collapsed at the family home in Blackpool, Lancashire, in the early hours of 20 November 2020. The Judge found that the expert evidence in the case of Professor G, of Professor N and of Professor D each at times fell below the high standard expected of expert witnesses giving evidence before the family court in this jurisdiction. This judgment illustrates a number of important lessons for expert witnesses. The criticisms go well beyond a disagreement between experts—they concern the duties of an expert to the court. An expert who appears to defend a predetermined hypothesis rather than follow the evidence risks losing credibility entirely, regardless of their qualifications or experience. This judgment illustrates that methodological rigour, transparency, and impartiality are essential to persuasive expert testimony.

The applicant, who required leases over mineral rights, could not agree with the owners of those rights on compensation and valuation issues. The expert witnesses for both parties had previously acted as expert advisors to their clients. However, while one expert witness understood that their role was not to advocate for a particular party or outcome but to assist the court, the other expert was unable to disassociate their longstanding role as an expert advisor from their duties to the court.

The trial dealt with liability issues relating to the alleged use of prohibited defeat devices. That is, devices which reduce the effectiveness of a vehicle’s emission control system for which there is no excuse or applicable exception. The judge criticised three of the expert witnesses for not complying with their duties under Part 35, and praised others.

The Claimant brought a claim in negligence against the Defendant, a dental practitioner, about the Defendant’s alleged failure to provide her with adequate advice about the risks and benefits of the treatment options available to her. The Claimant’s expert lacked understanding of the Bolam test, had not considered the dental notes, and was forced to make significant concessions in the joint report.

The Claimant alleged that the Defendant was in breach of the agreement between the parties for the supply of single alpha chain collagen. The judge was critical of the Claimant’s expert witnesses, in particular noting that he would have had to direct further accounting expert evidence be produced, if the evidence had been required.

This year’s Annual Conference discussed AI, independence, credibility, transparency and the changing expectations on expert witnesses.