Admissibility of expert evidence in medical negligence cases (EXP v Barker)

Admissibility of expert evidence in medical negligence cases (EXP v Barker)

The Court of Appeal upheld the trial judge’s rejection of evidence of an expert witness in the medical negligence case of EXP v Barker [2017] EWCA Civ 63. Grahame Aldous QC and Stuart McKechnie of 9 Gough Square, barristers, who acted for the respondent in the case, review the decision.

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What are the practical implications of this case?

The decision of the Court of Appeal reinforces the importance of the independence and objectivity of expert witnesses and the primacy of their duty to the court. Specifically, this case highlights the desirability that an expert witness should have no actual or apparent interest in the outcome of proceedings. If there is a potential conflict of interest, then it is imperative that this is disclosed with full particularity at the very earliest stage. If this does not happen, then the court is likely to be highly critical of those who failed to disclose the facts and also to reject that evidence.

What issues did this case raise?

The case was about whether a doctor can avoid a finding of clinical negligence by relying on an expert who has been shown to lack impartiality, independence or objectivity so as to undermine the credibility of his/her evidence. The claimant had suffered a catastrophic aneurysm bleed requiring lifesaving surgery and resulting in devastating neurological injuries. It was alleged on her behalf that the aneurysm had been visible on a MRI brain scan taken 12 years earlier in 1999, but had not been identified and so was not followed-up and treated. In his defence, the defendant relied upon expert evidence from Dr Andrew Molyneux (an eminent consultant neuroradiologist) who opined that the MRI scan showed no clear evidence of a cerebral aneurysm.

As a result of cross-examination at trial, it was revealed that the defendant and his expert witness had a long and extensive connection going back many years involving Dr Molyneux training the defendant at the Radcliffe Infirmary in Oxford, assisting and inspiring him in his career development, helping him obtain posts in the UK and abroad, writing at least one peer reviewed publication together and serving at the same time on the committee of the British Society of Radiologists. The extent of the relationship between the two specialists was inadvertently disclosed during cross-examination when Dr Molyneux referred to the defendant by his first name ‘Simon’, in what the judge described as an unguarded moment.

After a four-day trial in February 2015 Mr Justice Kenneth Parker rejected the suggestion that it had been for the claimant to investigate the defence witnesses before trial, holding that the responsibility for disclosure lay firmly on the defence side. He concluded that there had been a very substantial failure to disclose the nature and extent of the connection between defendant and his expert so that the court would have a complete understanding of all matters that could realistically affect Dr Molyneux’s independence as an expert witness.

Mr Justice Kenneth Parker went on to note that he had come very close to ruling Dr Molyneux’s evidence inadmissible on the grounds that the court could not have confidence in his impartiality and objectivity as an expert witness. The Court of Appeal considered that, had he done so, it would have been a proper decision that he would have been entitled to make. However, the judge decided that he should admit the evidence that had been heard, but subject to powerful arguments regarding its weight. Having considered the expert evidence, Mr Justice Kenneth Parker concluded that he had complete confidence in the objectivity and independence of the claimant’s expert evidence. He therefore much preferred to accept their opinions than the opinion of Dr Molyneux, whose independence and objectivity had been very substantially undermined. Accordingly he rejected Dr Molyneaux’s evidence and there was judgment for the claimant.

To what extent is the judgment helpful in clarifying the law in this area?

Both judgments confirm that the lack of impartiality and independence of an expert witness can go to the admissibility and weight afforded to such evidence. If the impartiality and independence of such a witness have been significantly compromised, the court is likely to reject such evidence by ruling it inadmissible or admitting and affording it little weight.

What are the implications for practitioners? What will they need to be mindful of when advising in this area? Any best practice tips?

The case has implications for expert witnesses and those that instruct them. When an expert witness is instructed, they should be asked whether there is any potential conflict of interest with a party involved in proceedings. This should form part of a standard letter of instruction. If a potential conflict does exist and the expert continues to act, this should be disclosed to the opposing party at the very earliest opportunity and discussed at the case management stage so that the court can decide whether to permit such evidence. If this is not done then the expert will, in fact, be doing no favour to the instructing party as it could seriously damage that party’s prospects at trial.

Are there still any unresolved issues practitioners will need to watch out for? If so, how can they avoid any possible pitfalls?

The case confirms that lack of independence and objectivity can go to admissibility of expert evidence in England and Wales. Complete openness is the only protection.

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Interviewed by Bridget O’Connell. The views expressed by our Legal Analysis interviewees are not necessarily those of the proprietor.

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