In the case of Martine Robinson and Liverpool University Hospital NHS Foundation and Dr Chris Mercier in the County Court at Liverpool, the judge ordered expert witness Dr Mercier to pay £50,000 in costs, following the ruling that the witness had acted in a wholly unreasonable and negligent manner.

This is a warning to all expert witnesses to ensure that they only accept instructions on matters within their expertise; to help and assist the Court on matters within their expertise; to keep their duty to the Court under constant review and to understand that their duty to the Court is theirs alone and that it is not for another party to police that duty.

The background to the case was that a claim for dental negligence had been brought by Ms Robinson against the hospital trust - for treatment that she had received at Aintree Hospital. It concluded with Ms Robinson withdrawing her claim after evidence was given by the expert witness, Dr Mercier.

In the ruling the judge stated:

"I formed the view during trial that Dr Mercier was not making any efforts to assist the court, but instead wilfully sticking to his case theory irrespective of the questions asked or the evidence given. His evidence was grossly unhelpful and wholly unreliable in my judgement. I will not at this stage detail examples of the same, because it is not relevant to this application. The application before me is predicated on the specific assertion that it should have been obvious to Dr Mercier at the outset, and at various stages throughout the proceedings, that he was not the appropriate expert to opine on the management and treatment afforded to the claimant on 8th November 2016."

The judge concluded that, but for Dr Mercier’s report the claim would not have been brought and added:

“All costs claimed within the defendant’s cost budget are therefore caused by Dr Mercier’s flagrant disregard for his duty to the court. A public body has been put to considerable expense in financing costly litigation that should not have been brought.

Although it is not part of my considerations, I observe that a hard-working oral and maxillofacial surgeon was maligned in public and undoubtedly caused significant distress by the actions of Dr Mercier."

Simon Berney-Edwards - EWI Chief Executive Officer, said:

"This case once again highlights the importance of those giving expert evidence understanding their role and their duty to the court. That absolutely includes highlighting where a matter is out of your area of expertise as Dr Mercier should have done. Members of the Expert Witness Institute sign up to a code of professional conduct and ensure they understand their role and duty to the court.”