Expert Witnesses: Importance of Expert Independence

EXP v Charles Simon Barker [2017]

Date published





The United Kingdom’s Court of Appeal, upholding the High Court’s decision, rules that the Trial Judge had not erred in finding that a consultant neuroradiologist had been negligent. Further, the Judge had been entitled to find that the independence and objectivity of the Appellant’s expert witness had been undermined by a failure to disclose that they had previously worked together.


The importance of expert independence and objectivity should not be undermined. It is well-known that experts should be independent and impartial when giving evidence and owe their primary duty to the court. This decision reinforces this principle and confirms that experts should be open and upfront with their instructing lawyers and the court, about any connection they have with parties to the claim. Failure to do so may result in their evidence being discredited and/or rendered inadmissible.


In 2011, the Respondent patient suffered a ruptured aneurysm in the brain. In 1999 she had had an MRI brain scan, which the Appellant neuroradiologist had reviewed and reported as being normal. The issue at trial was whether the scan indicated the presence of an aneurysm which a reasonably competent neuroradiologist would have identified and reported.

The Appellant's expert thought that the scan showed features consistent with the normal anatomy of the brain, whereas the Respondent's expert believed the scan to show an abnormality and that further investigation should have been performed.

The Trial Judge preferred the Respondent expert's evidence. It was also revealed that there was a close connection, described as “lengthy and extensive”, between the Appellant and his expert, having previously worked and co-authored research papers together. The Judge stated that the court's confidence in that expert's independence and objectivity had been undermined by his failure to disclose this close connection and whilst the judge refused to declare the expert’s evidence as inadmissible altogether, he commented that he would “bear powerfully in mind” the reservations he had about the expert’s independence and objectivity.

On appeal the Appellant submitted that the Trial Judge:

1) had failed to correctly identify and apply the Bolam test; and

2) having admitted his expert's evidence, failed to evaluate that evidence on its merits. It was submitted the Judge had wrongly performed a "balancing act" between competing expert opinions and had erred in holding that expert had an interest or bias in the outcome of the case which was sufficient of itself to dismiss his expert opinion when set against that of the Respondent’s expert.

The Court of Appeal held that:

1) the trial judge had correctly applied the Bolam test. The Respondent succeeded in establishing negligence in the conventional way, applying the Bolam test; and

2) the trial Judge was fully entitled to take the view that the Appellant’s expert had compromised his approach, such that the weight to be accorded to his views must be considerably diminished. The expert had failed to disclose his connection with the Appellant to the legal team well ahead of the trial.

The Court of Appeal emphasised that “the adversarial system depended 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 made known any associations or loyalties which might give rise to a conflict.”

Read other items in Hong Kong Medical Law Brief - April 2017