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Bryan Thomas provides an insight into the importance of experts in clinical negligence trials - Interviewed by Lexis Nexis

The importance of experts in clinical negligence trials (Arksey v Cambridge University Hospitals NHS Foundation Trust and Smith v Royal Liverpool Hospitals NHS Trust) 

Personal Injury analysis: Bryan Thomas, barrister at Civitas Law, describes two clinical negligence cases in which he acted for the claimant, but which had different outcomes as a result of the courts’ assessment of the expert evidence. In Arksey v Cambridge University Hospitals NHS Foundation Trust, the High Court found the evidence by the claimant’s expert fell far below the standard to be expected of a reasonable, competent expert witness with at one stage the expert even using an expletive. In Smith v Royal Liverpool Hospitals NHS Trust, the County Court preferred the claimant’s expert and found the defendant’s expert to be ‘inflexible’. 

Arksey v Cambridge University Hospitals NHS Foundation Trust[2019] EWHC 1276 (QB) Smith v Royal Liverpool Hospitals NHS Trust [2019] Lexis Citation 89 

What were the background facts to the cases?
Arksey v Cambridge University Hospitals NHS Foundation Trust 

The claimant suffered a sentinel bleed from a cerebral aneurysm at home and attended hospital. The defendant NHS Trust accepted that the hospital had been in breach of its duty to the claimant when it discharged her instead of admitting her. The next day, she had a major subarachnoid haemorrhage (SAH) that caused her to collapse and suffer permanent brain damage. 

Her case before the High Court was that as the hospital had a pre-operative protocol for SAH patients who were awaiting to have a coil placed in their aneurysm, she should have been admitted to the ward and the hospital should have implemented the protocol, which would have involved bed rest, blood pressure monitoring and appropriate hydration. Her expert, a consultant neurosurgeon, stated that a new haemorrhage while awaiting coiling in hospital was uncommon—in his clinical experience, they comprised 2-3% of neurosurgical SAH cases and, therefore in hospital, it was highly unlikely she would have had a new bleed before the aneurysm was coiled. 

There was also a separate minor issue of whether treatment for her hydrocephalus caused by the new haemorrhage, which the defendant admitted had been undertaken three-and-a-half months later than it should have been, had actually been, as the claimant maintained, a year too late. 

Smith v Royal Liverpool Hospitals NHS Trust 

One week later, Liverpool County Court heard another case concerning a hospital’s failure to diagnose correctly. The claimant’s wife had a terminal brain tumour. Following surgery, she underwent radiation chemotherapy and was administered various drugs. She started to display symptoms which the hospital diagnosed as neutropenic sepsis caused by her cancer treatment. After she died a few weeks later, the post-mortem report revealed that she had been suffering from invasive aspergillosis, a fatal condition. 

The claimant argued that if his wife’s condition had been diagnosed, it would have been successfully treated, so that she would have been able to live for the remainder of what was her reduced life expectancy due to her brain tumour. 

Once again, the defendant NHS Trust admitted breach of duty and the issue was causation. Prior to the trial the merits had been assessed. The claimant’s expert evidence appeared logical and reasonable. The defendant was alleging the cause of death was not invasive aspergillosis but liver failure. However, it had not adduced any hepatology evidence in support of this defence. 


It appeared that the claimant could succeed on behalf of his wife’s estate if the court accepted the expert evidence. In the days before the trial, the defendant’s expert served 12 additional papers in support of his claim that the claimant’s wife would, in any event, have died of liver failure at about the same date. In many ways this was a more difficult case for the claimant, as there were two very experienced clinicians giving evidence that they had taken all realistic steps in trying to successfully treat the deceased. 

What is expected of an expert at trial? 

In C v North Cumbria University Hospitals NHS Trust [2014] EWHC 61 (QB),[2014] All ER (D) 176 (Jan), Green J gave the following helpful guidance: 

  • 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—this is so even if there is another body of appropriate opinion which condemns the same act or omission as negligent 
  • 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 
  • 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 

What did the courts decide?
Arksey v Cambridge University Hospitals NHS Foundation Trust 

With regard to the claimant not being admitted to hospital after the first bleed, the defence expert was of the opinion that the claimant would have been better off at home than on a noisy ward. Although this appeared to take no account of the positive benefits of the protocol treatment, the judge accepted the defence expert’s assertion that resting in hospital would not have made any difference to the claimant and would not have avoided the SAH the next day. 

The judge rejected the evidence of the claimant’s expert on all areas of dispute and found that his evidence ‘fell far below the standard to be expected of a reasonable, competent expert witness, both in relation to the preparation of his reports and in relation to his preparing to give evidence’. The judge was also critical of the claimant’s lawyers in not ensuring the expert’s report was completely compliant with CPR 35. 

An issue that concerned the judge was the omission of the claimant’s expert to update his report to include reference to the lay witness evidence. His condition and prognosis (C&P) report was served under CPR PD 16.3.4 before the lay witness evidence was exchanged. His causation report predated the exchange of witness statements. He was provided with the witness evidence by the claimant’s solicitors and had confirmed at that stage that the evidence did not affect his opinion. He had failed to note a relevant medical event referred to by the treating neurosurgeon in his statement. This was on the minor issue of the delayed treatment to the claimant for hydrocephalus, but he gave the judge the impression that he had not seen the medical entry until shortly before the trial. This was incorrect, and the statements and the relevant medical entry had been in evidence through the defendant’s expert report. The expert’s reply was seen by the judge as a way of avoiding the obvious answer. While this was a minor separate issue unrelated to the main case, it seriously undermined his evidence. This point had a knock-on effect from which he never recovered. 

It would have been astonishing if the claimant’s solicitors had not provided the lay evidence to their expert and sought his comments. In my experience, it has been commonplace for many claimant and defendant solicitors to receive replies from experts that the lay witness statements did not cause them to change their opinion, 

not to obtain an addendum report confirming this and referencing the statements. The problem was that the claimant’s expert in this case failed to confirm this and to explain satisfactorily why it did not impact upon his opinion. 

When pressed on the issue relating to the medical history, he had incorrectly asserted that he had only had the full medical records a week before the trial when he had the trial bundle. However, all the experts in this case had the same medical records from the outset, nothing relevant was added later. His problems did not end there, as the judge found his manner to be intemperate, at one stage he even used an expletive, and he failed to address the questions that he was being asked. Recognising the difficulties of some of the questions, he strayed into other areas, which the judge found to be a deliberate ploy to avoid answering the questions, rather than any kind of misunderstanding as to what he was being asked. 

The court gave judgment for the defendant on the main issue as the claimant had not established that her staying in hospital would have avoided the SAH. However, it found for the claimant on the minor issue regarding the treatment for hydrocephalus where the defendant had admitted breach of duty in that the hospital should have carried out the treatment three-and-a-half months earlier than it did. 

Smith v Royal Liverpool Hospitals NHS Trust 

This time both experts received some criticism from Cox J, due to their lack of any experience of the latest effective treatment (voriconazole) that the claimant’s wife needed to avoid the deterioration in her invasive aspergillosis that led to her death. The claimant’s expert was a consultant public health physician. The defendant relied on a consultant physician in chest diseases and general medicine. An important factor in the judge’s consideration came from information within the late admission of research papers by the defendant’s expert concerning the efficacy of voriconazole compared with earlier less effective drug treatment. 

This time the judge preferred the claimant’s expert. He found the defendant’s expert to be ‘inflexible’. The judge described the latter’s unwillingness to properly consider the possibility of using voriconazole as a possible treatment as ‘striking’ and found that it probably stemmed from his lack of a familiarity with the medication. Furthermore, the defendant’s expert had stated that a hepatologist’s entry in the clinical notes concerning satisfactory liver condition was wrong, despite not being himself a hepatologist and had asked the court to accept that the hepatologist was wrong without any real basis for doing so, other than pointing to the liver function tests and clinical notes, which is what the hepatologist would have seen as well. This was an issue which the judge found led to his rejection of the evidence from the defendant’s expert. 

The court gave judgment for the claimant, concluding that if his wife had received voriconazole, on the balance of probabilities, she would have made a recovery from the invasive aspergillosis and that she would have gone on to recover from the effects of the allergic reaction to the cancer treatment. 

What are the practical implications of the judgments and what pitfalls should clinical negligence practitioners look out for? 

When presenting expert evidence, practitioners should ensure that it satisfies the reasonable and logical test mentioned in C v North Cumbria University Hospitals. This could avoid the risks of the trial process and achieve settlement before trial. 

They should ensure that the report remains in draft form until the statements are exchanged and then ask the liability/causation expert to include the comment that the statements have been read and whether the expert’s opinion has changed, and if so, an explanation should be given. Alternatively, if the report has not remained in draft form, an addendum will need to be produced containing that information. 

The Form H must contain an estimated cost to provide for an updated or addendum report that is compliant with CPR 35 in every case (C&P as well as liability/causation). 

It is not unusual for medical records to be incomplete in some respects. To avoid any issue, the lawyer should request that the expert checks the medical records and confirms that they appear complete or that any suspected omissions are pointed out. 



If an expert is giving a précis of a medical entry, then that should be expressly stated in the body of the opinion and, ideally, the complete note should be annexed and cross-referred to by the expert. 

The liability/causation expert should attend a conference when proceedings are drafted but not served, and also well in advance of the trial date, probably as soon as the expert evidence is exchanged. 

Lawyers should ensure that their expert is the correct expert to give the evidence to support the relevant issue being advanced, whether it is within the claim or the defence. 

It is necessary to check that the expert has relevant experience of the condition and latest treatment in issue, preferably in an NHS setting if that is where the alleged negligence arose. An expert who retired many years ago and whose retirement is spent expressing expert opinions for solicitors may turn out to be far removed from the fray and much more likely to form an opinion divorced from current practical reality. 

If any equipment has caused injury, lawyers should make certain that the expert has used it and is familiar with it, has the model, make and the manufacturer’s instructions and has considered those instructions. 

Where a drug is the required treatment, it is necessary to establish that the relevant part of the British National Formulary has been considered. 

Where there are any clinical guidelines, lawyers should make sure they are recited accurately and commented upon expressly. 

Practitioners should take the time to meet in conference with their experts and should not refrain, out of respect or for fear of reproach from them, from cross-examining them by putting all points when preparing the expert evidence for exchange or for trial. 

Practitioners should make sure that any published material in support of the expert evidence is disclosed with the report or at least well in advance of the joint statement stage. The late application on the morning of the trial for the admission of this evidence by the defence in Smithcould have caused the trial to be vacated with costly costs consequences. 

Clinical negligence trials are not commonplace as there are serious risks to both sides. No trial is straightforward from either perspective. Reported cases seem to confirm a success rate at trial that is the same for either party. Solicitors are normally accepting of an expert’s respectability providing there are relevant qualifications and appropriate experience. Some experts are resentful of criticism or questioning and solicitors and counsel are then reluctant to thoroughly cross-examine their own expert witness in preparing the evidence and assessing the strength of their own case. It is essential that the expert evidence is carefully reviewed at the crucial stages, when other evidence is disclosed and at the pre-trial stage. The process requires attention to detail and district judges budgeting these cases have to appreciate that this is a time-consuming process involving the experts, sometimes four or more per side, solicitors and counsel. 

With even the best preparation and planning, at trial events can take a different course. Normally, the decision by the judge to prefer one expert to another is decided on a knife edge by small and subtle differences in explanation and logic. However, most practitioners have not seen their expert actually give evidence at trial. Inherent in all trials, for both sides, is the risk that once in the witness box an expert’s earlier confident demeanour can change, the witness can be caught out by an unexpected question, experience and attention to detail is then called into question and the expert reacts inappropriately and become evasive as a defence mechanism. Having worked many hours to make the long, costly and arduous journey to trial, the lawyer can find the case is lost in a heartbeat—such are the risks of a clinical negligence trial. 

Bryan Thomas appeared for the claimant in Arksey and for the claimant in Smith.
Interviewed by Robert Matthews.
The views expressed by our Legal Analysis interviewees are not necessarily those of the proprietor.