Day in the life of an Expert Witness

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 Appellant, a citizen of Tajikistan, was appealing the Respondent’s decision to refuse his protection claim. The Judge gained the distinct impression that the Appellant’s expert witness was simply advocating on behalf of the Appellant, rather than assisting the Tribunal by providing a critical, objective expert opinion on the context. In doing so, he trespassed into the role reserved for the Tribunal.

Having written in Hospital Update, 48 years ago, about routine parenteral thiamine alongside prophylaxis or treatment of alcohol withdrawal symptoms, I read this with great interest. It should be of interest to physicians and psychiatrists but what is striking are the lessons for all experts. There is a long section in which the judge is critical of some of the experts and their evidence.

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 proceedings related to a petition asserting unfair prejudicial conduct of the affairs of a company. The expert witness who provided valuation evidence, wrote to the court three months after the trial expressing concerns about his own valuation report.

The Claimants, who were trustees of an angling association which has fishing rights on the River Tees, asserted that the Defendant had interfered with their property rights. The Judge was disappointed that the hydrology experts had inspected the river when it was in very different conditions of water flow. The expert hydrology evidence was also limited to water flow, with no expert evidence available to the Judge on the impact on fish or fishing. One of the experts had also failed to comply with CPR Part 35.

The judgment dealt with the defendant's application for reverse summary judgment or to strike out the claimant's claim and the claimant's application to strike out the defendant's application and for a stay of related proceedings. The claimant attempted to submit a non-compliant report as 'independent expert evidence' to support his application without obtaining permission to do so.

Cam Askan v HM Land Registry [2026] EWHC 1352 (Ch)

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.