The claim in Griffiths v TUI UK Limited [2021] EWCA Civ 1442 concerned gastric illness allegedly suffered as a result of consuming contaminated food or drink while staying at a hotel in Turkey on an all-inclusive package holiday. The medical evidence was from the unopposed report of a gastroenterologist. The defendant was critical of the report and the evidence on causation in closing submissions to the judge, and the lack of reasoning in support of the conclusion. But it should be emphasised, the defendant had not produced its own report for the hearing supportive of its case. In the High Court, the judge concluded that there was no requirement in the (Civil Procedure Rules) CPR to provide reasoning in an expert report and that so long as the report complied with the requirements of the CPR, the judge was bound by its conclusions.

The majority in the Court of Appeal allowed the appeal against the judge’s decision. The majority view provides important warning to any party – and any expert – using a formulaic or light-weight expert report, relaxed in the knowledge that the opposing side has not obtained (or at least is not using) its own report with a contrary opinion.

Requirement to provide reasoning

An expert is required to provide reasoning for the conclusion and any opinions provided.

Although reasoning is only referred to within the CPR under practice direction 35, paragraph 3.2(6), (b), where there is a range of opinion, some reasoning is necessary to support an expert’s conclusion. Otherwise, it is all but worthless. It is common sense, according to the Court of Appeal, that if the expert is to fulfil their overriding duty to assist the court, it is inevitable that a report must contain a basis for the expert’s conclusions.

The Court pointed out that this is also reflected in paragraph 62 of the guidance, which provides that:

1. The summary of conclusions should be at the end of a report “after the reasoning”

2. The judge may be “assisted in the comprehension of the facts and analysis if the report explains at the outset the basis of the reasoning”.

The guidance clearly expects there to be reasoning shown within the report.

Obviously, the extent of the reasoning required will depend upon what is necessary in the circumstances and given the nature of the opinion provided.

Can a court reject an uncontroverted report?

The High Court judge had taken the view that he was bound by an unopposed and uncontroverted report. The Court of Appeal was clear that a judge may apply a critical mind to the contents of the report and that a court may reject a report, even where it is uncontroverted, if it is a bare ipse dixit (an unproven statement). In most circumstances, it is likely that such a report would not meet the requirements set out in CPR Part 35, in any event. However, if the opinion is contained in only a few sentences, there might be circumstances in which such evidence could be accepted; for example, if the sentences contained an opinion as to whether a certain chemical was present in a compound. Where the expert evidence is the form of an evaluative opinion, a mere ipse dixit is all but worthless.

If the court is to be satisfied as to the conclusion reached, or in a case like Griffiths, that the evidence is sufficient to enable the claimant to satisfy the burden of proof in relation to causation, some chain of reasoning supporting the conclusion is necessary, even if it is short.

In Griffiths, the first indication that the defendant did not accept the uncontroverted expert evidence was in closing submissions to the judge. The Court of Appeal found that there was no need for the defendant to give advance notice that it did not accept the expert report, or that it intended to challenge it on the basis that it did not provide adequate reasoning. The criticism of the report can be raised at any time and the judge can critically assess the weight of the expert evidence.

Dealing with range of opinion

The provision in practice direction 35 3.2(6) in relation to an expert dealing with a range of opinion is not always easy to apply:

3.2 An expert’s report must:

(6) Where there is a range of opinion on the matters dealt with in the report –

(a) Summarise the range of opinions; and
(b) Give reasons for the expert’s own opinion.

The expert, when expressing an opinion, must go on to consider whether there is a possible range of opinions, however much the expert may consider that there is only one reasonable opinion. The expert must then provide a summary of the range of opinions with which they do not agree, deciding how much of that range needs to be provided to the court and at what point the range ceases to be sufficiently reasonable to be provided, before stating why they come where they do within the range.

Given that giardia and two different viruses were found in Mr Griffiths’ samples, the expert raised (in the report) the question of whether Mr Griffiths might have suffered two illnesses rather than one (but did not elaborate upon that issue at all). Issues also arose in relation to the incubation period for giardia. Finally, Mr Griffiths had consumed food at and outside of the hotel. There was therefore obviously scope for a range of opinion. This was even more so, in light of the expert’s acceptance of various publications as reliable sources in his answer to a Part 35 question. This all raised the possibility of causes of Mr Griffiths’ illness other than food and drink, which the expert did not address, but in relation to which there would also have been a range of opinion.

In his report, the expert set out a statement of the approach which experts would take and stated that he did the same. However, it does not follow that all experts would reach the same conclusion as this expert, or as to where his opinion fell within the range.

The expert did not, therefore, provide a range of opinions and therefore did not meet the minimum standard required by practice direction 35.

Learning points

  • An expert must provide the reasoning by which an opinion is reached. The degree of detail necessary in providing this reasoning will depend on the nature of the opinion expressed, but the reader must be able to understand how the expert has weighed up the evidence, which facts are relied upon and how the conclusion is reached. Even a short report on a simple issue should contain, and show, reasoning. For more on expressing opinion evidence and the structure of reports see Chapter 11 of Writing Medico-Legal Reports in Civil Claims – an Essential Guide – Eyre and Alexander.
  • If an expert does not provide reasoning, the judge is entitled to reject the opinion, even if there is no contrary expert evidence. The report, however brief, must contain sufficient reasoning to enable the judge to assess the basis on which an opinion is reached, and to find it satisfactory (on the balance of probabilities).
  • It is open to the opposing party to make criticism of the report for the first time in concluding submissions to the judge at the end of the hearing. There is no requirement for the opposing party to give notice that that is what it intends to do. Therefore, the expert (and the legal team) must critically consider the expert report, in the same way they would if there was an opposing report, to ensure that it addresses all issues and provides adequate reasoning for any opinions expressed.
  • The expert must, when expressing an opinion, consider if there is a range of possible opinions. Unless it is a straightforward binary issue (‘yes’ or ‘no’), that is likely to be the case. The expert must then provide a summary of the possible range of opinions which similarly qualified experts might give and explain why their own opinion comes where it does, in that range.

Giles Eyre is a retired barrister and an Associate Member of Chambers at 9 Gough Chambers, London, having practised for many years in the field of injury claims and at the interface of law and medicine. He continues giving training and presenting workshops for experts on providing effective expert reports and evidence, and on medico-legal issues, in his own right and for training organisations.

He is co-author of Writing Medico-Legal Reports in Civil Claims – an essential guide (2nd edition 2015), and author of Clinical Practice and the Law – a legal primer (October 2018) both published by Professional Solutions Publishing and available through book retailers or from the author, and regularly writes articles on these subjects. He blogs on issues relevant to court experts in civil claims at

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