Day in the life of an Expert Witness

The Court excluded consideration of the expert testimony of an expert on the dangers of AI and misinformation, after he submitted an expert declaration which included fake AI-generated citations to two academic articles.

Kohls v. Ellison, 2025 WL 66514 (D. Minn. Jan. 10, 2025)

The two handwriting experts in this case were given completely different samples of comparator signatures and did not undertake the same task. The judge noted that it was extraordinary and unsatisfactory that the defendants’ expert was provided with comparator signatures which were not the person’s normal signature and was then instructed to assume they were authentic.

This case concerns the treatment of an ankle injury. Although the orthopaedic experts expressed fundamentally opposing views concerning the appropriate management of the injury and the court did have to resolve some issues by deciding whose evidence to accept, an unusual feature of this case was the significance of the fact that the evidence of the defendant orthopaedic surgeon evolved and developed during the course of the forensic process leading the court to the irresistible conclusion that the defendant's witness statement and his account at trial were almost certainly an amalgam of what the defendant thought and his expert’s opinion of which parts were found to have been copied and pasted into his witness statement. So, the court found that the defendant's account of his reasoning and recollection had been, no doubt unwittingly, influenced by expert opinion.

Ebanks-Blake v Calder [2025] EWHC 3327 (KB) 

The claimant, who suffered brain damage at birth, relied on a report commenting on the allegation of negligence prepared by Mrs S, a midwife. The judge was concerned about the objectivity of Mrs S’s expert evidence because she was heavily involved in the business of litigation and gave evidence which he considered was uncompromisingly critical of the defendant.

The details of this case are for gastroenterologists and psychiatrists. The learning points are of general application and although made by an expert in their first case, they reflect mistakes made by some more experienced experts who should know better.

Patricia's Father v Patricia (Rev1) [2025] EWCOP 30 (T3)

The judge found that the report by the claimants’ forensic accounting expert was not expert evidence because it simply reported what the underlying documents said in a more digestible way, without adding any expert opinion. On the one or two occasions where the expert did offer an opinion, they were not opinions on any accountancy matter.

The Claimant, on her solicitor’s advice, covertly recorded her testing by the Defendant’s neuropsychological expert. Weighing up the factors in favour of admitting the evidence and against admitting it, the judge considered that they were very finely balanced and quite difficult and that he may well have ruled that the evidence could not be relied on, if the Defendant’s expert had not himself inadvertently recorded the testing.

The task for the expert in this case was enormous. Capacity is issue specific. This means that if the issue is someone’s capacity to conduct legal proceedings, in this case sixteen sets of proceedings, the expert has to consider each set of proceedings. The person may have the capacity to conduct some and not others.

Johnston v Financial Ombudsman Service [2025] EWCA Civ 551