A recent High Court decision highlights the critical importance of expert witnesses in clinical negligence cases having a sound understanding of the “Bolam” test. While the test is not strictly determinative, a lack of familiarity can significantly undermine the credibility of their evidence.
1. What is this new pilot scheme?
In Tarrant v Monkhouse [2025] EWHC 2576 (KB) the claimant brought a negligence claim following complications from bariatric surgery. Shortly before trial, the pleadings were amended to narrow the scope of allegations, resulting in a liability-only trial focused on breach of duty and causation.
Both parties instructed bariatric surgery experts. During cross-examination, the claimant’s expert was questioned about their understanding of the “Bolam” test, which had been referenced in their report.
2. The Outcome
HHJ Simon stated that the “inability of an expert witness to recite the Bolam test by heart” is not “determinative of the value” of their opinion.
However, in this case, the claimant’s expert demonstrated a lack of basic understanding of the legal framework governing clinical negligence, which significantly undermined his credibility. The judge ultimately preferred the defendant’s expert evidence.
3. Specific Judicial Criticisms
HHJ Simon identified several issues with the claimant expert’s evidence:
- Inconsistent terminology, making the report difficult to follow.
- Lack of a coherent rationale for the opinions expressed.
- Inadequate understanding of the Bolam test, as revealed during cross-examination.
- Failure to engage adequately with the opposing expert’s views, leading the judge to favour the defendant’s evidence.
4. What can experts learn from this case?
This case serves as a reminder that expert witnesses in clinical negligence cases must not only comply with the requirements of CPR Part 35 and Practice Direction 35 but also demonstrate a clear understanding of the legal principles underpinning their role—particularly the Bolam test.
Our Clinical Negligence Essentials Part 1: substantive legal principles and case law for the expert witness course has been specifically designed for clinical negligence expert witnesses – ensuring that they understand and are up to date with the core legal principles that underpin clinical negligence litigation. One of the key learning outcomes of the course is breach of duty and standard of care, with specific reference to the legal tests applied in Bolam, Bolitho and Montgomery.
Please visit our website for details of our full training offering for expert witnesses.