An expert witness in a recent clinical negligence case has been admonished by the judge for failing to comply with CPR 35 in several respects, including intentionally favouring the claimant’s case.
1. Introduction
In Tosh v Gupta [2025] EWHC 2025 deputy high court judge Sarah Clarke KC had to decide whether the defendant, a consultant general colorectal and laparoscopic surgeon, had been negligent in the way he graded the claimant’s haemorrhoids, and in the subsequent advice he gave on the best way to treat them.
The expert witness for the claimant in this case was a retired general and colorectal surgeon with over 25 years' experience in a district general hospital. He admitted he had not done many haemorrhoidectomies and had never done a ligature haemorrhoidectomy, which was the procedure in issue in this case.
2. What was the judge’s main issue with the evidence of the claimant’s expert witness?
A key red flag for the judge in hearing the claimant’s expert’s evidence was that he overtly admitted that parts of his report amounted to “a piece of advocacy for the claimant”. This was in direct contravention of CPR 35, which calls for experts to remain objective and unbiased, sticking to the facts of the case.
Under cross-examination, the expert was asked whether it would be reasonable to recommend surgery if the claimant had grade 3 or 4 haemorrhoids. He replied saying that it would be. However, when he was asked why this was not mentioned in either of his reports or in the joint statements, he agreed it should have been and that its omission was a failure to comply with his duty to the court. “I think that’s a reasonable comment,” he told the court.
Due to the poor standard of the expert’s evidence and the fact that the defendant’s expert, had more relevant experience, the judge said, “where there is a conflict between the evidence, I unhesitatingly prefer the evidence of [the defendant’s expert]”.
3. Were there any other issues with the evidence of the claimant’s expert?
The claimant’s expert also undermined the credibility of his evidence by not fully addressing the defendant’s side of the case. His witness statement dated 21 July 2021 referred to him having read the claimant and defendant's witness evidence. However, these were only served in April 2024.
“He said that when the witness evidence was served, he did have regard to it, but his opinion had not changed since he wrote this 2021 report. This does not however explain how he was able to have regard to witness evidence in July 2021 when these statements did not even come into existence until 2024,” the judge said. “It was also pointed out to him that neither this expert report, nor his subsequent report dated 4 February 2022 made any reference to the defendant's case and nor had he analysed the defendant's case.”
The expert accepted that his evidence had not addressed the defendant’s case and that he was under a duty to assess the arguments on both sides and weigh them up fairly. He argued, however, that he had done despite not referencing the defendant’s arguments in his reports.
Elsewhere, the expert failed to admit he had changed his opinion and been wrong in his interpretation of some of the evidence on the claimant’s condition. “Again, it is a matter of concern that [the expert] was unwilling to admit what is obvious to any reader – which is that he has completely changed his mind by the time of the joint statement… Instead, [the expert] gave a confusing and rather incoherent response,” the judge pointed out in her ruling.
The judge recalled the defendant’s counsel asking the claimant’s expert witness whether he had changed his opinion to which he replied, “I agree it is not clear.”
“Therefore, despite being given three chances to concede that he had obviously changed his mind, he was unable to do so. This does not appear to comply with his duties under PD 35, which requires that ‘if after producing a report, an expert’s view changes on any material matter, such change of view should be communicated to all the parties without delay, and when appropriate to the court.’”, the judge said.
4. How did these issues impact the judgment in the case?
Aside from lacking the appropriate level of expertise for this case, the expert appeared to have completely neglected his duty to the court throughout the case. He chose to place himself firmly on the side of the instructing party and to fight their corner, rather than comply with his duties under Part 35 of the CPR, particularly his overriding duty to the court.
It is impossible to say whether an alternative expert witness would have led to an alternative outcome for the claimant. However, this expert did not help the claimant’s case and likely harmed his own reputation as a credible expert witness for future instructions.
The judge ruled that the claimant failed to prove her case on liability and causation, and the claim was dismissed.
5. What are the key learnings for expert witnesses?
The case offers lessons for experts in the importance of being aware of, understanding and complying with all their duties and responsibilities under Part 35 of the CPR. It also presents can example of what not to do if your evidence changes during the case or is found to be confusing or incoherent.
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