Jeremy Ford’s Digest May

A note on expert evidence in clinical negligence cases, inspired by the decision of Alexander v HCA International Ltd & Anor (attached) decided on 29 May 2026. This has given me an ideal opportunity to remind you of broader principles of expert evidence in such cases.

In Alexander the claimant succeeded due to a failure to administer rectal Diclofenac before an ERCP, the claimant going on to suffer life-threatening necrotising pancreatitis. On causation, one of the defendants’ gastroenterologists argued that the claimant had to satisfy a 95% statistical confidence interval before causation could be established. HHJ Roberts rejected this: the civil standard is the balance of probabilities (more than 50%) not the scientific standard a medical journal would demand, and the expert had applied the wrong test, failing to answer the question the court actually had to decide.The same expert had agreed in the joint statement that the drug should have been prescribed on the prescription chart, then tried at trial to downgrade that legal requirement to a mere “ideal”. The judge found this reflected detrimentally on his credibility.

A second defence expert had stated in his report that he would not expect any discussion of the suppository during the consent process, a position contradicted by all the other evidence, which he abandoned in the joint statement. That too diminished his credibility as an independent expert and reduced the weight the court gave his evidence generally.

Similar lessons run through Tarrant v Monkhouse (Oct 2025, attached), a clinical negligence claim in which the claimant’s expert evidence did not withstand scrutiny, and the claim was lost. The issues concerned bariatric surgery, but have far wider relevance. There HHJ Simon dismissed the claim, preferring the defendant’s expert, not on professional standing, but on the way the report and the oral evidence held up at trial.

The claimant’s expert had cited the Bolam test by name in his report, but when asked on cross-examination to explain it, he could not. The judge’s view was that an inability to recite the test is not, on its own, determinative but the absence of a working grasp of the legal framework on which the opinion rests was a real concern, and, combined with the incoherence of the opinion itself (inconsistent use of “stricture”, “stenosis” and “narrowing”, no clearly reasoned basis for the position taken, and an inability to answer the points raised by the other side’s expert), it led the judge to prefer the defendant’s expert under the principles in C v North Cumbria University Hospitals NHS Trust (2014) (also attached: paras 20 – 25 are a very useful reminder of the tests in both Bolam and Bolitho and how they are applied –  extracted below for your convenience)

• If your report cites a legal test (Bolam, Bolitho, Montgomery, material contribution), be ready to explain it in your own words at trial and make sure you understand the framework you are working within, including the burden and standard of proof. Applying a scientific or publication standard instead of the balance of probabilities is the same error as being unable to explain Bolam.
• Read your report through for consistency of terminology before it is served. Inconsistent terms (or the same term used in two senses) will be picked up on cross-examination and will erode the weight of the report.
• For every opinion, set out the chain of reasoning that ties it to the underlying clinical material. “In my opinion…” without a stated rationale is essentially worthless.
• Engage with the other side’s expert: in your joint statement, in any supplementary report, and again at trial. Re-stating your own position is not engagement, and it leaves the opinion exposed when the contrary points are put to you.
• Do not easily resile from concessions made in the joint statement. You will be held to them, and retreating at trial or downgrading a requirement you previously accepted, reads as partisan and damages your credibility across the board.
• If the letter of instruction does not explain the legal framework clearly, ask for more clarity. Pathway will happily advise you directly on such issues (email me directly).

“I myself would prefer to put it this way, that he is not guilty of negligence if he has acted in accordance with a practice accepted as proper by a responsible body of medical men skilled in this particular art…Putting it the other way around, a man is not negligent, if he is acting in accordance with such a practice, merely because there is a body of opinion that would take a contrary view”.

“Differences of opinion and practice exist and will always exist in the medical and other professions. There is seldom only one answer exclusive of all others to problems of professional judgement. A Court may prefer one body of opinion to the other, but that is no basis for a conclusion of negligence”.

23.  The test was subjected to analysis in Bolitho v City and Hackney Health Authority [1997] UKHL 46; [1998] AC 232 . An issue was whether a Court was required to accept the views of one truthful body of expert professional advice even though the Court was unpersuaded of its logical force. It was submitted that to adopt such an approach was “wrong in law” because it was ultimately for the Court, not for medical opinion, to decide what was the standard of care required of a professional in the circumstances of a particular case. Lord Brown Wilkinson stated as follows:

“My Lords, I agree with the submissions to the extent that, in my view, the Court is not bound to hold that a defendant doctor escapes liability for negligent treatment or diagnosis just because he leads evidence from a number of medical experts who are genuinely of opinion that the defendant’s treatment or diagnosis accorded with sound medical practice. In the Bolam case itself, McNair J stated…that the defendant had to have acted in accordance with the practice accepted as proper by a “ responsible body of medical men”.

Later, he referred to “a standard practice recognised as proper by a competent reasonable body of opinion”. Again, in the passage which I have cited from Maynard’s cases, Lord Scarman refers to a “respectable” body of professional opinion. The use of these adjectives – responsible, reasonable and respectable – all show that the Court has to be satisfied that the exponents of the body of opinion relied upon can demonstrate that such opinion has a logical basis. In particular, in cases involving, as they so often do, the weighing of risks against benefits, the judge before accepting a body of opinion as being responsible, reasonable or respectable, will need to be satisfied that, in forming their views, the experts directed their minds to the question of comparative risks and benefit and have reached a defensible conclusion on the matter”.

24.  Later, having cited various authorities, Lord Brown Wilkinson stated:

“These decisions demonstrate that in cases of diagnosis and treatment there are cases where, despite a body of professional opinion sanctioning the defendant’s conduct, the defendant can properly be held liable for negligence (I am not here considering questions of disclosure or risk). In my judgment that is because, in some cases, it cannot be demonstrated to the judge’s satisfaction that the body of opinion relied upon is reasonable or responsible. In the vast majority of cases the fact that distinguished experts in the field are of a particular opinion will demonstrate the reasonableness of that opinion. In particular, where there are questions of assessment of the relative risks and benefits of adopting a particular medical practice, a reasonable view necessarily pre-supposes that the relative risks and benefits have been weighed by the experts in forming their opinions. But if, in a rare case, it can be demonstrated that the professional opinion is not capable of withstanding logical analysis, the judge is entitled to hold that the body of opinion is not reasonable or responsible.

I emphasise that in my view it will seldom be right for a judge to reach the conclusion that views genuinely held by a competent medical expert are unreasonable. The assessment of medical risks and benefits is a matter of clinical judgment which a judge would not normally be able to make without expert evidence. As the quotation from Lord Scarman makes clear, it would be wrong to allow such assessment to deteriorate into seeking to persuade the judge to prefer one of two views both of which are capable of being logically supported. It is only where a judge can be satisfied that the body of expert opinion cannot be logically supported at all that such opinion will not provide the benchmark by reference to which the defendant’s conduct falls to be assessed”.

• i)  Where a body of appropriate expert opinion considers that an act or omission alleged to be negligent is reasonable a Court will attach substantial weight to that opinion.
• ii)  This is so even if there is another body of appropriate opinion which condemns the same act or omission as negligent.
• iii)  The Court in making this assessment must not however delegate the task of deciding the issue to the expert. It is ultimately an issue that the Court, taking account of that expert evidence, must decide for itself.
• iv)  In making an assessment of whether to accept an expert’s opinion the Court should take account of a variety of factors including (but not limited to): whether the evidence is tendered in good faith; whether the expert is “responsible”, “competent” and/or “respectable”; and whether the opinion is reasonable and logical.
• v)  Good faith: A sine qua non for treating an expert’s opinion as valid and relevant is that it is tendered in good faith. However, the mere fact that one or more expert opinions are tendered in good faith is not per se sufficient for a conclusion that a defendant’s conduct, endorsed by expert opinion tendered in good faith, necessarily accords with sound medical practice.
• vi)  Responsible/competent/respectable: In Bolitho Lord Brown Wilkinson cited each of these three adjectives as relevant to the exercise of assessment of an expert opinion. The judge appeared to treat these as relevant to whether the opinion was “logical”. It seems to me that whilst they may be relevant to whether an opinion is “logical” they may not be determinative of that issue. A highly responsible and competent expert of the highest degree of respectability may, nonetheless, proffer a conclusion that a Court does not accept, ultimately, as “logical”. Nonetheless these are material considerations. In the course of my discussions with Counsel, both of whom are hugely experienced in matters of clinical negligence, I queried the sorts of matters that might fall within these headings. The following are illustrations which arose from that discussion. “Competence” is a matter which flows from qualifications and experience. In the context of allegations of clinical negligence in an NHS setting particular weight may be accorded to an expert with a lengthy experience in the NHS. Such a person expressing an opinion about normal clinical conditions will be doing so with first hand knowledge of the environment that medical professionals work under within the NHS and with a broad range of experience of the issue in dispute. This does not mean to say that an expert with a lesser level of NHS experience necessarily lacks the same degree of competence; but I do accept that lengthy experience within the NHS is a matter of significance. By the same token an expert who retired 10 years ago and whose retirement is spent expressing expert opinions may turn out to be far removed from the fray and much more likely to form an opinion divorced from current practical reality. “Respectability” is also a matter to be taken into account. Its absence might be a rare occurrence, but many judges and litigators have come across so called experts who can “talk the talk” but who veer towards the eccentric or unacceptable end of the spectrum. Regrettably there are, in many fields of law, individuals who profess expertise but who, on true analysis, must be categorised as “fringe”. A “responsible” expert is one who does not adapt an extreme position, who will make the necessary concessions and who adheres to the spirit as well as the words of his professional declaration (see CPR35 and the PD and Protocol).
• vii)  Logic/reasonableness: By far and away the most important consideration is the logic of the expert opinion tendered. A Judge should not simply accept an expert opinion; it should be tested both against the other evidence tendered during the course of a trial, and, against its internal consistency. For example, a judge will consider whether the expert opinion accords with the inferences properly to be drawn from the Clinical Notes or the CTG. A judge will ask whether the expert has addressed all the relevant considerations which applied at the time of the alleged negligent act or omission. If there are manufacturer’s or clinical guidelines, a Court will consider whether the expert has addressed these and placed the defendant’s conduct in their context. There are 2 other points which arise in this case which I would mention. First, a matter of some importance is whether the expert opinion reflects the evidence that has emerged in the course of the trial. Far too often in cases of all sorts experts prepare their evidence in advance of trial making a variety of evidential assumptions and then fail or omit to address themselves to the question of whether these assumptions, and the inferences and opinions drawn therefrom, remain current at the time they come to tender their evidence in the trial. An expert’s report will lack logic if, at the point in which it is tendered, it is out of date and not reflective of the evidence in the case as it has unfolded. Secondly, a further issue arising in the present case emerges from the trenchant criticisms that Mr Spencer QC, for the Claimant, made of the Defendant’s two experts due to the incomplete and sometimes inaccurate nature of the summaries of the relevant facts (and in particular the Clinical Notes) that were contained within their reports. It seems to me that it is good practice for experts to ensure that when they are reciting critical matters, such as Clinical Notes, they do so with precision. These notes represent short documents (in the present case two sides only) but form the basis for an important part of the analytical task of the Court. If an expert is giving a précis then that should be expressly stated in the body of the opinion and, ideally, the Notes should be annexed and accurately cross-referred to by the expert. If, however, the account from within the body of the expert opinion is intended to constitute the bedrock for the subsequent opinion then accuracy is a virtue. Having said this, the task of the Court is to see beyond stylistic blemishes and to concentrate upon the pith and substance of the expert opinion and to then evaluate its content against the evidence as a whole and thereby to assess its logic. If on analysis of the report as a whole the opinion conveyed is from a person of real experience, exhibiting competence and respectability, and it is consistent with the surrounding evidence, and of course internally logical, this is an opinion which a judge should attach considerable weight to.

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