In a significant recent decision, in TUI UK Ltd v Griffiths  UKSC 48, the Supreme Court has rejected arguments that uncontroverted expert evidence could nevertheless be rejected by the trial judge. In doing so, the Court has confirmed the importance of procedural fairness under the English common law, holding that in general, where a party contends that witness and expert evidence should be rejected, they must challenge that evidence by way of cross-examination.
The facts of the case – whilst unfortunate – are not uncommon in the County Court: Mr Griffiths and his family went on an all-inclusive holiday where he contracted acute gastroenteritis which caused permanent digestion issues. Mr Griffiths issued a claim against the tour operator he had booked with, TUI, contending that the illness was caused by consuming contaminated food and drink at the hotel. Mr Griffiths supported his case with witness and expert evidence, including that of a microbiologist who opined that, on the balance of probabilities, Mr Griffiths' illness was caused by the food or drink served at the hotel.
TUI did not provide any expert evidence to counter the microbiologist's report, nor did it seek to have the microbiologist attend the trial for cross-examination. The expert evidence was therefore (to borrow the words of Lord Hodge, who wrote the judgment of the Supreme Court) "uncontroverted in the sense that it was not in conflict with any other evidence led at the trial and was not subjected to challenge by cross-examination". However, in closing submissions TUI's counsel argued that report was incomplete in its explanations and failed expressly to discount on the balance of probabilities other possible causes of Mr Griffith' illness, with the result that he had failed to prove his case – a conclusion that the trial judge accepted.
After appeals to the High Court and the Court of Appeal, the case came before the Supreme Court. The key question was whether the trial judge had been right to reject the microbiologist's report in circumstances where it was not illogical, incoherent or inconsistent, or based on any misunderstanding of the facts or unrealistic assumptions. Under the adversarial system adopted in English civil proceedings, the judge must assess expert evidence for adequacy and persuasiveness, but the parties frame the issues for the judge to decide in their pleadings and conduct at trial. In that context it is an important part of the judge's role to make sure the proceedings are fair and so, the issue at the heart of the appeal concerned the requirements of a fair trial.
Following a review of some wonderfully historic cases, including The Queen's Case (1820) (the trial in the House of Lords of Queen Caroline for adultery when King George IV sought to annul his marriage to her), Lord Hodge held that the general rule is that a party is required to challenge by cross-examination the evidence of any witness on material points that they wish to submit should not be accepted. If the position were otherwise, Lord Hodge explained, there could be (among other things) unfairness to the witness whose evidence is being impugned, whether on the basis of dishonesty, inaccuracy or other inadequacy. Furthermore, cross-examination "gives the witness the opportunity to explain or clarify his or her evidence".
Lord Hodge made clear, however, that the rule is flexible, and will not always apply. For example, where a bald assertion is made in an expert’s report without any reasoning to support it, where an obvious mistake has been made, or where an expert has been given a sufficient opportunity to respond to criticism or otherwise clarify their report.
So, what does this all mean? English common law has maintained its reputation for the fairness of its trials and provided an important reminder that parties should take an active role in testing the opponent's evidence. While it will not always be necessary for a defendant to go to the expense of obtaining a detailed expert report in circumstances where the claimant has submitted an inadequately reasoned report, they should, at least, ensure that appropriate questions are posed to the expert so that there is an opportunity to respond to any challenges that may be made.