Recent Developments in Expert Witness Liability in UK Courts

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Although generally immune from suit in the United Kingdom, experts can still be sanctioned by the court in the form of costs orders. UK Courts in the recent case of Robinson v Liverpool University Hospitals NHS Trust and Mercier [2023] EWHC 21 (KB) however have shown that they err towards protecting experts from being sued, even in the absence of expert witness immunity.

The case confirms an ongoing trend towards protecting expert witnesses from suit in common law countries, and may pave the way for standards of expert witness liability should Australian courts decide to follow the UK in abolishing expert witness immunity.

Abolition of Expert Witness Immunity in UK Courts

UK courts abolished expert witness immunity in Jones v Kaney [2011] UKSC 13. The case concerned a claim in negligence brought by the applicant, a victim of car accident, against his expert witness. The consultant psychiatrist expert witness had mistakenly signed a joint statement with another expert confirming that the applicant had grossly exaggerated their PTSD symptoms, leading the applicant to settle for significantly less than the amount to which they were in fact entitled.  The court considered the expert’s conduct sufficiently serious and exceptional in both consequence and failure of expert witness duties to warrant an available legal remedy.

The court also refuted arguments against the removal of the expert witness immunity firstly by maintaining that the abolition would not significantly compromise expert witness impartiality to the extent of becoming harmful to public interests. The routine and uncontroversial functioning of advocates who are also liable to clients provided ample evidence that experts were capable of balancing their loyalty to clients against their duty to the court to remain impartial. Secondly, the court rejected as inaccurate the assumption that the removal of expert witness immunity would deter experts from taking up expert witness work.

High Standard for Costs Orders Against Experts

The recent case of Robinson v NHS Trust and Mercier demonstrates that although experts are not liable to suit, the extent of misconduct warranting a costs order remains exceptionally high in UK courts.

The case at first instance involved a claimant who engaged a general dentist expert witness to assess the procedures of an oral & maxillofacial surgeon that led to the failure to extract the claimant’s tooth. The defendant NHS Trust sought a Costs Order against the expert after Counsel for the claimant withdrew from the matter without formal explanation but presumably on the basis of the expert’s inability to provide unbiased and helpful evidence: the expert evidence displayed blatant attempts to ignore facts and questions contradicting the claimant’s case theory, and failed to address facts and relevant legal tests fundamental to assessing whether there had been a breach of duty.

The court justified a costs order against the expert on the basis of the direct causal relationship between the expert’s behaviour and the NHS Trust’s costs. The expert’s misleading initial report with its unreliable findings of negligence constituted the main impetus for the claimant’s decision to bring costly proceedings against the Respondents.

On appeal, however, the flawed content of the expert’s report and its connection to the Respondent’s expenditure was insufficient to meet the exceptional standard of the evidence as “reckless and in flagrant disregard” for experts’ duties that warrants costs orders against experts. The court held that such costs orders should be reserved for far more egregious examples of misconduct by the expert, such as the total unsuitability of the expert’s field of expertise to the issues in the matter.

Insofar as the dental practitioner’s knowledge and experience overlapped with those of the maxillofacial surgeon with regard to tooth extraction, the claimant’s expert was qualified to provide an opinion and therefore did not overstep his duty in any reckless or flagrant manner. The agreement between the appealing expert and other engaged experts on several points in their written reports further highlighted to the court the unexceptional nature of the appealing expert’s conduct.


UK Courts reserve costs orders against expert witnesses for exceptional instances of misconduct by the expert witness. This standard usually involves more than unreliable or unhelpful content in reports and in court testimony. UK cases involving costs orders against expert witnesses have emphasised the minimum requirement of exceptional circumstances and the “reckless” and “flagrant disregard” for expert witness duties. The impact of the expert’s misconduct on the costs and consequences of the case also play a factor in deciding whether the circumstances are sufficiently exceptional, but certainly do not form the main basis of UK courts’ consideration.

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