The High Court of England and Wales has considered the question of whether a trial court is entitled to reject a plaintiff’s expert evidence, where no expert evidence has been preferred by the defendant.

The claimant had suffered food poisoning while visiting Turkey, and brought an action against the travel company. He relied on the report of a consultant microbiologist to prove causation. The trial judge in the County Court was critical of the report, and concluded that the expert had not addressed sufficient questions, nor addressed alternative causes of illness:

[I]t seems to me that reports prepared after Wood v TUI [2018] QB 927 ]need to deal with those matters the Court of Appeal specified. These reports do not do that. In some instances, they do not comply with CPR 35 (the failure to supply a range of opinion). They certainly do not provide me with sufficient information to be able to say that there is a clear train or logic between, for example, the incubation periods and the onset of illness, so that the pre-flight meal can be excluded or that the hotel food is a more likely cause; similarly for the ‘second’ illness – it is not said why it is more likely to be a relapse rather than a second infection, especially where the expert has said that it would be unlikely to have all the identified pathogens from one episode of eating contaminated food. It is thus not clear why the eating out in the local town can be discounted.”

The case was dismissed at trial.

On appeal to the High Court, it was submitted that, although the expert had not addressed all relevant questions, it was not ‘mere ipse dixit’ [unsupported statement]. The High Court agreed:

In the absence of direct authority on the issue, I take the view that a court would always be entitled to reject a report, even where uncontroverted, which was, literally, a bare ipse dixit, for example if Professor Pennington had produced a one sentence report which simply stated: “In my opinion, on the balance of probabilities Peter Griffiths acquired his gastric illnesses following the consumption of contaminated food or fluid from the hotel.” This would qualify within Clarke LJ’s “difficult to imagine” because, in these days of CPR Part 35 and the well-publicised duties of experts, it is difficult to imagine an expert producing such a report. However, what the court is not entitled to do, where an expert report is uncontroverted, is subject the report to the same kind of analysis and critique as if it was evaluating a controverted or contested report, where it had to decide the weight of the report in order to decide whether it was to be preferred to other, controverting evidence such as an expert on the other side or competing factual evidence. Once a report is truly uncontroverted, that role of the court falls away. All the court needs to do is decide whether the report fulfils certain minimum standards which any expert report must satisfy if it is to be accepted at all.

The High Court concluded that the trial judge was not entitled to reject the report once it had been put into evidence.

However strong the criticisms of Professor Pennington’s report, and I accept that those criticisms were strong, they went to an issue with which the learned judge was not concerned, namely the weight to be ascribed to the report, that being an issue which would only have arisen if the report had been controverted in the sense set out in paragraph 10 above. By ascribing, effectively nil weight to the report, the learned judge was ruling that the report did not meet the minimum requirements for it to be accepted as evidence in the case, and in that respect I take the view that she was wrong.

The High Court’s decision must be considered questionable. If a trial court is not satisfied that a plaintiff has proved his or her case on the balance of probabilities, it must always be open to the judge to dismiss it. If an expert report does not address some of the relevant issues satisfactorily, and the judge is not persuaded that the case has been proven, the plaintiff’s case should be dismissed. Undue deference should not be given to an expert witness who has failed to address the issues properly.