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Legal case

Challenging expert evidence

TUI UK Limited (Respondent) v Griffiths (Appellant) UK Supreme Court - judgment 29 November 2023


The claimant in the underlying action, Mr Griffiths, suffered a serious stomach upset whilst on holiday abroad staying at an ‘all inclusive’ hotel. The claimant and his spouse gave uncontested factual evidence at trial. Prior to trial, the claimant served a report from a medical expert who linked the claimant’s condition to the food and drink he had consumed at the hotel.

The defendant did not obtain an order compelling the claimant’s expert to attend trial for cross-examination and served no evidence of its own. However, the defendant’s closing submissions contained a detailed critique of the claimant’s expertise. At first instance, the judge was persuaded that the claimant had failed to prove his case.

The claimant appealed to the High Court where Mr Justice Spencer allowed the appeal concluding that the case raised important issues as to the status of uncontroverted expert’s evidence.

Court of Appeal 

TUI lodged an appeal to the Court of Appeal where, by a majority, (Bean LJ dissenting) it was successful.

The majority concluded that the trial judge had to evaluate all the evidence to include uncontroverted expert evidence and decide what weight to apply in reaching conclusions on the factual issues,

“Uncontroverted evidence may be compelling, but it may not be; it may be inherently weak or unhelpful for other reasons”.

Bean LJ’s dissent was strongly worded,

“In my view, Mr Griffiths did not have a fair trial of his claim. The court should not allow litigation by ambush”.

The issues raised on appeal 

The Supreme Court distilled the questions raised on appeal as follows:

  •  What is the scope of the rule based on fairness, that a party should challenge by cross-examination evidence in its submissions at the end of trial?
  •  Does the rule extend to an attack in submissions on the reliability of a witness’s recollection and on the reasoning of an expert witness?
  •  If the rule does extend so far, was there unfairness in which the trial judge concluded the trial in this case?

Supreme Court findings   

The leading judgment was given by Lord Hodge. The conclusions he reached were:

  1. The general rule in civil cases, as stated in Phipson on Evidence (20th edition, 2022), is that a party is required to challenge by way of cross-examination the evidence of any witness of the opposing party on a material point which it submits to the court should not be accepted.
  2. In the current adversarial system, the purpose of the rule is to make sure the trial is fair. This includes fairness to the party who has adduced the evidence of the impugned witness and the impugned witness themselves who may have a professional interest in maintaining his/her reputation.
  3. Cross-examination gives the witness a chance to explain or clarify their evidence.
  4. The rule should not be applied too rigidly.

Applying these principles to the facts, the Supreme Court concluded that in the absence of a proper challenge on cross-examination, it was not fair for TUI to advance criticisms of the expert’s reports in its closing submissions or for the trial judge to accept those submissions.

Consequently, the Supreme Court held that,

“both the trial judge and the majority of the Court of Appeal erred in law in a significant way”.

The Supreme Court in its own assessment of the evidence concluded that the claimant had established his case on the balance of probabilities.


This unanimous judgment re-affirms the principles said to constitute a “fair trial”.  This includes rendering it impermissible for a party who seeks to criticise or demolish an expert’s opinion in closing submissions where the evidence has been rendered “uncontroverted” by a failure to adduce evidence of its own or by cross-examination.

The judgment may be viewed as “disappointing” by those facing large volumes of low value cases – for example “holiday sickness claims” - as this judgment compels the defendant either to cross-examine the expert at trial or adduce expert evidence of its own if that expert has an unchanged opinion after Part 35 questions. This may add cost to the proceedings.

Conversely, this judgment means that experts’ reports can be agreed in advance of trial, thus narrowing the points in dispute and avoiding, in Lord Justice Bean’s words, ‘litigation by ambush’.