Claims against expert witnesses: an update

We comment on our recent experience of these claims. When is a claim against an expert likely to succeed, how common are they and how do we see them developing?

 It has been over five years since expert witness immunity was removed by the Supreme Court in Jones v Kaney [2011]. The five year anniversary of the decision coincided with Kennedys’ instruction to respond to a letter of claim which alleged negligence on the part of a fire safety consultant engaged as an expert witness. For the purposes of this article, we will call this case C v D.

Breach of duty

The decision in Jones v Kaney, which reversed authority dating back over 400 years, was that expert witnesses are not immune from claims in respect of matters connected with their participation in legal proceedings.

In reaching its decision and expressing its surprise that immunity had remained unchallenged for so long, the Supreme Court considered the duties owed by an expert to the court and their client: whilst an independent and unbiased opinion falling outside a range of reasonable expert opinion would not be a breach of duty to the court, it could clearly be a breach of the duty owed to the expert’s client. In accordance with established principle, what is within the “range of reasonable expert opinion” will be judged by reference to the standard of a reasonably competent practitioner of the relevant discipline.

Practical implications

Our experience suggests two types of claims, where the expert is alleged to have:

  • Failed to review a joint report and ensure that it reflected their views prior to signing it, so that significant concessions were inadvertently made in the litigation, as in Jones v Kaney; and/or
  • Fundamentally changed their position.

Assuming that an expert is found to have breached their duty, the claim to loss will mirror to a great extent a claim against lawyers for negligent litigation advice, comprising damages for:

  • Costs which would not otherwise have been incurred.
  • The lost opportunity to obtain a better outcome.

Recent example

In C v D, the expert fire safety consultant not only failed to read the joint report which he had signed but also tried to cover his mistake by fabricating emails. The other party became aware of this and the expert’s integrity was fatally undermined. The instructing solicitors applied to court for permission to replace the expert, which was granted.

Of course, this had costs ramifications. As the claim was substantial and complex, these costs were high (around £140,000). In the subsequent claim against the expert, damages were sought in respect of these costs. We were instructed to defend the claim.

The claimant did obtain compensation for approximately two-thirds of its increased costs, as the evidence of the expert acting dishonestly was persuasive and he did not cooperate with our investigations. However, we successfully defended two additional and larger claims in full:

  • The claimant sought compensation for the lost chance to win damages in respect of a number of allegations which the expert had supported in his first report, only to concede them in joint discussions. We argued that there could not have been a lost chance if the claimant’s allegation of breach of duty was that the expert’s original report was wrong. Such a claim must be based on the assertion that the views underpinning the concessions were wrong and therefore that the other party’s evidence was also wrong. It is hard to envisage a court finding against the conclusions of two experts in the same field. It also suggests that other reasonably competent members of that speciality would have come to the same conclusion, so that there was no breach of duty in the first place.
  • They also sought damages to reflect the court’s reduction of the costs award made in the claimant’s favour at the end of the trial. The court had taken the concession of allegations into account when assessing the claimant’s conduct. This was difficult to evaluate due to the broad-brush approach taken by the court. However, it was clear that this was not the only aspect of the claimant’s conduct which the court had found unreasonable.


Despite concerns that the landmark ruling in Jones v Kaney would make expert witnesses reluctant to give frank evidence or act at all, we have seen little evidence of this. In a recently reported survey of over 750 experts, whilst just over a quarter said they had considered giving up expert work, fear of being sued was a minor consideration after levels of pay and time restraints. Our experience over the last five years is indeed that these claims are infrequent.

Where an expert has failed to read a report before signing it, then clearly such a significant error will result in damages for the costs of remedy and/or lost opportunity. Claims such as these may crop up now and again, but will be unusual. However, where the claim is in respect of allegedly negligent concessions, there are significant conceptual and evidential difficulties for a claimant to overcome, as outlined above. So, although claims against experts are still very much in their infancy, they are likely to remain unusual – for the time being.