A Word of Warning to all Expert Witnesses; Ensure you are Qualified to Comment on the Issues at Hand

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The matter of Robinson v Liverpool University Hospitals NHS Trust & Dr Mercier (County Court at Liverpool, 9 September 2021) concerned a dental negligence claim. Dr Chris Mercier was instructed to comment on breach of duty and causation and he had been supportive of the claim throughout. However, at trial, he accepted that the Defendant’s expert oral and maxillofacial surgeon was better placed to advise on the issues. The Claimant discontinued her claim and the Defendant applied for a Third Party Costs Order against Dr Mercier.


Mrs Robinson was referred to the Liverpool University Hospital by her dentist in August 2016. This was due to significant decay of two lower teeth that required removal. As Mrs Robinson became so distressed during an attempt to remove the teeth under local anaesthetic, her dentist referred her to Liverpool University Hospital for the procedure to be conducted under general anaesthetic.

The procedure took place on 8 November 2016 and Dr Bajwa took consent from Mrs Robinson to remove Mrs Robinson’s lower two molars in addition to a third upper tooth that was also significantly decayed. However, during the procedure, Dr Bajwa considered that the upper tooth was restorable and left this tooth in situ. The basis of Mrs Robinson’s claim was that Dr Bajwa was negligent in failing to remove the third tooth.

During proceedings, the Claimant instructed Dr Mercier to advise on breach of duty. He was supportive of the claim and opined that no reasonable dental surgeon would have concluded that the tooth was restorable. Dr Webster, for the Defendant, considered that the tooth was restorable and submitted that removing the tooth would have in fact been negligent. The case proceeded to trial on 7 and 8 December 2020.

The relevant principles

Part 35 of the CPR outlines the duties owed to the Court by an expert instructed in proceedings. More specifically, CPR 35.3(1) and (2) provides that experts have a duty to assist the Court on areas within their expertise and that this duty overrides any obligation to the individual who provided instructions.

CPR 46.2 and 46.8, along with Section 51 of the Senior Courts Act 1981, provides the Court with authority to make a Costs Order in favour of, or against, a non-party to proceedings, and against legal representatives. The Recorder noted that the White Book refers to the matter of Philips v Symes (No 2) [2004] EWHC 2330 (CH), where a costs order was made against an expert who had a “flagrant reckless disregard of his duties to the Court” however she noted that such an application should be exceptional.

The Recorder considered the 3 stage test applied within the case of Ridehalgh v Horsefield [1994] Ch 205, CA:

1. Had the [third-party] of whom complaint was made acted improperly, unreasonably, or negligently?;

2. If so, did such conduct cause the applicant to incur unnecessary costs?;

3. If so, was it, in all the circumstances, just to order the legal representative to compensate the applicant for the whole or part of the relevant costs?

The Recorder also referred to Walker and another v TUI UK Ltd [2021] 1 WLUK 398, noting that it is accepted that the threshold for experts is set higher than it is for legal representatives. This is on the basis that an expert is not in a position to determine how a case is conducted.

The Defendant’s submissions

The Defendant to the action submitted that it should have been obvious to Mr Mercier from the outset that, as a General Dentist Practitioner, he should not have been providing an opinion on the

standard of care afforded to the Claimant by an Oral and Maxillofacial Surgeon. The Defendant relied on three comments made by Dr Mercier in support of this:

1. That he had had no experience of surgical removal of teeth under General Anaesthetic since 2000 [79];

2. That he had no experience of consenting patients for the extraction of a tooth/teeth under General Anaesthetic [80]; and,

3. That he conceded that Mr Keith Webster, as Maxillofacial Surgeon working in a Hospital, was “better placed” to give expert evidence in the case


The Recorder considered the evidence of Dr Mercier and noted that his opinion had been inconsistent throughout proceedings. His finding of breach of duty was originally based on a failure to correctly review the Claimant, however he later concluded that the tooth was not restorable and it was a breach to fail to remove the tooth. The Recorder considered that Dr Mercier’s opinion fluctuated in line with whatever he though would win the case. Recorder Hudson also considered Dr Mercier’s background and noted that, given Dr Mercier’s lack of experience in the extractions and removals in a hospital setting, it should have been perfectly obvious at the outset that he was not suitably experienced to comment on the care provided by Dr Bajwa.

Recorder Hudson also considered Dr Mercier’s reference to the fact that no party had ever questioned his experience during proceedings. She concluded that, as CPR PD 35, para 2 clearly requires the expert to make it clear when a question or issue falls outside of their area of expertise, it is the duty of the expert, not another party to raise this.

The Recorder thereafter considered Dr Mercier’s submission that, as the allegations within the Particulars of Claim were not based on his findings, there was no causative link. This submission was dismissed as it was obvious that the claim would not have been pursued but for Dr Mercier’s opinion. Consequently, Recorder Hudson concluded that all of the Defendant’s costs were incurred as a direct result of Dr Mercier’s flagrant disregard for his duty to the Court. The recorder made an Order against Dr Mercier for a sum equal to the entirety of the Defendant’s budget, being £50,543.85.


This case illustrates the importance of the expert’s duty to the Court; it is imperative that an expert must not accept a referral if it is beyond his field of expertise and failing to take heed of the duties owed to the Court may result in significant costs consequences. It is interesting to note that these costs were purely awarded against Dr Mercier and that no liability on behalf of the Claimant’s solicitor was considered, despite the Court finding that it was obvious he was not the correct expert for the claim.

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