Expert witnesses required to disclose professional relationship

20 May 2015. Published by Adam Craggs, Partner

In the recent case of EXP v Dr Charles Simon Barker [2015] EWHC 1289 (QB), the High Court has emphasized the importance of the independence of expert witnesses and of disclosing any conflicts of interests at the earliest opportunity.

Although the case involved a claim for clinical negligence, the judgment is of relevance to tax appeals before the First-tier Tribunal ('FTT'), where the parties often seek to rely upon evidence from expert witnesses.


The claimant brought a successful claim for clinical negligence against Dr Barker in relation to his failure to identify the presence of an aneurysm in her brain. Both parties instructed their own medical experts. During the course of the trial, it emerged that Dr Barker and his expert witness had failed to disclose a long standing professional relationship. This raised an issue regarding the expert's credibility and the claimant argued that the expert evidence relied upon by Dr Barker should be declared inadmissible.  


Having considered the relevant authorities, Mr Justice Parker, reluctantly, allowed the expert's evidence. However, he confirmed that confidence in the independence and impartiality of experts plays an important role when courts and tribunals are evaluating the competing and often finely balanced judgements of rival experts. The judge said that he "came very close" to ruling the evidence inadmissible, as his confidence in the expert's independence and impartiality had been seriously undermined. The judge also made it clear that when deciding what weight to attach to the expert's evidence, he would take into account the reservations he had in relation to the expert.  


As mentioned in the introduction to this blog, both the taxpayer and HMRC often wish to call expert witnesses when litigating before the FTT, for example, in relation to the correct accounting treatment of particular entries in the taxpayer's accounts. In order to ensure that any such evidence is objective and impartial, the parties should of course call experts who are independent of either party.  Although such a statement is self-evident, it is surprising how often HMRC seek to call an employee of the department to provide expert accounting evidence. Such an expert is certainly not independent of HMRC, and it is questionable whether an expert who is connected to the party calling him (by way of employment) can provide an objective opinion.

A tax appeal can turn on whose expert evidence the FTT prefers, and the Barker case is a timely reminder of the importance of independent and impartial expert evidence and of the duty experts owe to the court.

EXP v Dr Charles Simon Barker [2015] EWHC 1289 (QB

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