Expert evidence, independence and objectivity: EXP v Barker [2017] EWCA Civ 63

By Peter Yates

In EXP v Barker, the trial judge and Court of Appeal were faced with an unusual situation. An expert witness – although undoubtedly skilled and experienced in his field – had omitted to mention a close personal connection to the party instructing him.

EXP brought a claim against Dr Barker, a neuroradiologist, alleging that he had negligently failed to identify and report a cerebral artery aneurysm. After suffering an episode of visual disturbance in 1999, EXP underwent an MRI scan, on which Dr Barker reported. He concluded that the scan was entirely normal; it was EXP’s case that the scan was not normal and in fact disclosed the presence of an aneurysm on her right middle cerebral artery.

Causation was conceded – if there had been an aneurysm which had been spotted, EXP would have been referred to the relevant surgical teams who would have offered treatment with a high likelihood of success and an excellent long-term prognosis.

In the event, in 2011 EXP suffered an acute parenchymal haemorrhage caused by a ruptured aneurysm. EXP was left with a range of physical and mental difficulties, including visual loss, weakness on the left side of her body, chronic pain and spasticity, impaired speech and senses, disinhibited behaviour, depression and panic attacks.

The issue for the trial judge was a narrow one: “whether the MRI scan in 1999 did indicate the presence of an aneurysm which a reasonably competent neuroradiologist would have identified and reported”.

The experts

EXP relied on two experts. Primarily, she relied on Dr Butler, a neuroradiologist. She also relied on the supplementary evidence of Mr Kirkpatrick, a consultant neurosurgeon.

Dr Barker relied on the evidence of Dr Molyneux, a consultant neuroradiologist. He also served reports from Mr Byrne, a consultant neurosurgeon. Mr Byrne’s reports largely went to causation.

Both experts clearly had distinguished careers. They were at loggerheads; Dr Molyneux was of the view that the MRI scans showed a twisting of the artery, and no abnormality. Dr Butler, by contrast, stated that the image showed an aneurysm. EXP’s neurosurgeon, Mr Kirkpatrick, from his neurological perspective, added that the images were “clearly abnormal”. Mr Byrne’s report referred to a particular article relating to aneurysms (“the ISUIA study”) with the implication that, even had an aneurysm been present and identified, surgical intervention would not necessarily have been recommended (although as causation was conceded shortly before trial, the opinion itself ceased to be relevant).

It became apparent (at trial) that there was in fact a close personal connection between Dr Barker and Dr Molyneux. Their respective CVs indicated that they had worked at the same institute, but did not mention each other (even though Dr Barker’s CV had specifically mentioned another senior practitioner by whom he had been taught). As the judge noted, someone comparing their CVs might infer that there had been (possibly significant) contact between Dr Barker and Dr Molyneux. However:

It emerged only in cross-examination at the trial that the connection between Dr Barker and Dr Molyneux had been lengthy and extensive. Dr Molyneux had trained Dr Barker during his seven years of specialist radiology training, and in particular had trained him for two and a half years as a registrar and senior registrar in neuroradiology, including the particular area of interventional radiology in which Dr Molyneux specialised and in which Dr Barker had a special interest. It is clear that they had worked together closely over a substantial period. They had written together a paper for the 14th International Symposium on radiology, a paper not shown on Dr Molyneux’s list of publications [emphasis added by the Court of Appeal], and Dr Molyneux told the Court that they might have co-operated on other papers which he could no longer specifically recall. Dr Molyneux helped Dr Barker to obtain foreign placements … Dr Barker accepted that Dr Molyneux had guided and inspired his practice, and Dr Molyneux had helped Dr Barker become a consultant in Southampton. They had also been officers together on the committee of the British Society of Radiologists, Dr Barker having been Treasurer at the time when Dr Molyneux, being a committee member, was nominated President.

It also emerged that Dr Barker had suggested that Dr Molyneux should be a defence expert. He had first been asked in cross examination whether he had chosen Dr Molyneux as an expert, which he denied, and he had had to be prodded with a further question to elicit the full picture.

In addition to the personal connection, it became apparent that Dr Molyneux had a connection to the ISUIA study referred to by Mr Byrne. The study had in fact been the subject of intense criticism, to the extent that the credibility of those involved in the study had been “severely compromised”. That was significant because Dr Molyneux had been an executive committee member of the ISUIA and “could have been expected to know of the criticisms of the study and to realise that Mr Byrne’s evidence was seriously deficient and misleading.”

The trial judge’s view was that the failure to disclose this connection was “a very substantial failure indeed”, particularly because there had been a specific direction in the case that the experts should disclose details of any employment or activity which raised a possible conflict of interest. In relation to the ISUIA study, the trial judge stated that Dr Molyneux:

knew that Mr Byrne’s report was being relied upon in respect of what, until very shortly before the trial, was an important contested issue, yet Dr Molyneux did nothing at that stage to draw the attention of Mr Byrne, or anyone else, to what he knew to be the case. The justification for this appeared to be that Mr Byrne was the expert on neurosurgery, and it was not within Dr Molyneux’s remit to comment on any aspect of the neurosurgical evidence.

I find that explanation difficult to accept.

EXP sought to exclude Dr Molyneux’s evidence altogether. The judge refused to take that course, partly because it would result in Dr Barker’s case immediately failing. He added, however, that

…I must bear powerfully in mind, when I assess the weight that I should give to the evidence, the reservations that I retain about Dr Molyneux’s independence and objectivity in this case

Ultimately, the judge at first instance concluded that the aneurysm that ruptured in 2011 was an aneurysm that was present in 1999. Assessing the competing experts’ views, the judge stated that

Where the core issue in a case turns, as it does here, on the court’s ability to evaluate the competing and finely balanced medical judgements of rival experts, the court’s confidence in the independence and impartiality of the respective experts must play an important role. I have to say, with considerable regret, that by reason of the matters set out earlier in this judgment my confidence in Dr Molyneux’s independence and objectivity has been very substantially undermined. On the other hand I have complete confidence in the independence and objectivity of Dr Butler, and I much prefer to accept his judgement, formed on the basis of his great experience and skill, that (i) a competent neuroradiologist would have been considerably troubled by the relevant images from the 1999 MRI scan; and (ii) would not have concluded that those images could be prudently and adequately explained by “normal brain anatomy”, contrary to Dr Molyneux’s view; and (iii) would have concluded that the images did show the presence of an aneurysm.

The judge substantiated this conclusion by relying also on the evidence of Mr Kirkpatrick. He was a neurosurgeon rather than a neuroradiologist, but neither the judge nor the Court of Appeal had any hesitation in concluding that his evidence was of real worth.

EXP succeeded in establishing liability.

The appeal

Dr Barker appealed on two broad grounds: that the judge failed to formulate and apply the correct Bolam test; and that, having admitted the expert evidence of Dr Molyneux, the judge failed to evaluate it on its merits and impermissibly performed a “balancing exercise” between the two experts, concluding that Dr Molyneux’s interest in the outcome was sufficient of itself to dismiss his opinion.

The first set of grounds was dismissed in short order. The judge had properly stated and applied the correct Bolam test.

Dealing with the second set of grounds, counsel for Dr Barker referred to the well-known authorities. The Court of Appeal summarised the conclusion of the House of Lords in Maynard v West Midlands RHA [1984] 1 WLR 634:

it is not sufficient for a judge to conclude that one body of opinion is preferable to another, if both are within the range of reasonable professional views. It is necessary, before the threshold is passed, to show that no responsible body of relevant professional opinion would say the practice was reasonable.

In Bolitho v City and Hackney HA [1998] AC 232 the House of Lords concluded that

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. … [T]he court has to be satisfied that the exponents of the body of opinion relied upon can demonstrate that such opinion has a logical basis.

[I] 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 …. 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.

Counsel for Dr Barker submitted that the judge chose not to exclude the evidence of Dr Molyneux, whose expertise he explicitly recognised. If the evidence was admitted, so the argument went, Dr Molyneux’s expertise meant that his evidence should necessarily be accepted as establishing that a responsible body of neuroradiologists would not have referred EXP for further investigation. Put simply, “cannot resolve the matter unless, on close analysis, he finds the views of Dr Molyneux to be unreasonable.”

In reply, counsel for EXP submitted that, as the judge had found Dr Molyneux to be lacking the necessary independence, he was entitled to put less weight on his evidence. The authorities make it clear that a lack of independence can properly go to admissibility or to weight. It was not a case where the judge was required to find that the body of opinion represented by Dr Molyneux was unreasonable; it was simply that the judge was unable to rely on his evidence as to acceptable practice.

The appeal was dismissed. The judge had been entitled to take the view that the weight to be attached to Dr Molyneux’s evidence was considerably diminished, and indeed would have been justified in excluding it altogether.

Our adversarial system depends heavily on the independence of expert witnesses, on the primacy of their duty to the Court over any other loyalty or obligation, and on the rigour with which experts make known any associations or loyalties which might give rise to a conflict. Dr Molyneux failed to do so here, despite an express direction to that effect. Indeed, the omission of mention of papers co-authored with Dr Barker points in the other direction.

[In relation to the ISUIA study] the scrupulous expert in Dr Molyneux’s position should be pointing out the problem to the legal team well ahead of trial.

In addition to the fact that Dr Molyneux had no explanation for the apparent coincidence between the benign “tortuosity” he had purported to identify in the 1999 scan and the location of the ruptured aneurysm, the Court of Appeal added that

it is clear that the judge simply did not feel able to rely on Dr Molyneux’s evidence as establishing that a responsible body of neuroradiologists would have failed to refer the Respondent. In my view he had no obligation to do so. The Respondent succeeded in establishing Bolam negligence in the conventional way. This was not one of those “rare cases” where a Claimant was driven to show that established medical practice was unreasonable. The judge had a considerable body of evidence, firmly expressed by those with proper expertise, to support both the presence of an aneurysm in 1999, and the proposition that any responsible properly qualified neuroradiologist should and would have referred the Respondent for further investigation on the basis of the 1999 MRI scan.

The case turned on its facts, and the judge was entitled to reject Dr Molyneux’s evidence. The appeal failed.

The case is a stark reminder of the critical importance of the independence and openness of expert witnesses. Legal teams should be scrupulous about exploring and avoiding potential conflicts of interest. Where, as here, a close personal connection between an expert and the party instructing him emerges only at trial, it is difficult to see how the revelation could be anything other than fatal to that party’s case.


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