This is the first of a series of posts that consider the Court of Appeal judgment in  Griffiths v Tui (UK) Ltd [2021] EWCA Civ 1442.  That decision has considerable practical consequences for experts and any litigator commissioning or challenging expert evidence.  Here we look at the majority decision which upheld the decision of the trial judge, finding that the judge was not bound to accept the “uncontroverted” evidence of an expert.


“The judge cannot be prevented from considering the quality of such evidence in order to determine whether the burden of proof is satisfied just because it is uncontroverted. As Judge Truman stated, the court is not a rubber stamp. If it were otherwise, the court would be bound by an uncontroverted expert’s report which satisfied CPR PD 35, even if the conclusion was only supported by nonsense.”


This case, alongside a number of other recent cases on expert evidence, will be considered in the webinar “Expert Evidence – Understanding the Basics and Avoiding the Pitfall” on the 20th October 2021. Details of how to book are here. 



The claimant brought a case for damages for personal injury on the basis that he had suffered gastric illness whilst on holiday in Turkey. In support of his claim the claimant commissioned a report from Professor Pennington.  This was described as “short, indeed one could describe it as “minimalist”.   The report was admitted into evidence at the trial. The defendant put questions to the expert but did not call any evidence of their own, nor did they ask that the expert attend trial to be cross-examined.   The trial judge dismissed the claimant’s claim.   The claimant was found to be a totally honest witness, however the trial judge discounted the expert evidence and found that the claimant had not proven his claim.  This decision was overturned on appeal to the High Court judge, that decision was considered here. 

The High Court Judge found, in essence, that since the defendant did not call evidence to counter the expert’s evidence, and it was not challenged at trial (the report being admitted as evidence), it was not open to the trial judge to reject the conclusions of the expert report.


In Griffiths v Tui (UK) Ltd [2021] EWCA Civ 1442 the Court of Appeal overturned the decision of the High Court judge and reinstated the decision of the trial judge in favour of the defendant.  This was a 2 – 1 decision (and the dissenting judgment will be looked at in a later post).



Lady Justice Asplin set out the grounds for allowing the appeal. There was a detailed consideration of the requirements of an expert report and the rules relating to the admissibility of expert evidence which is not CPR 35 compliant.  The majority in the Court of Appeal did not accept the conclusion of the High Court judge that the trial judge had been bound to accept the conclusions of the expert.

    1. I should state at the outset, that in my judgment, the authorities do not support the bright line approach adopted by the Judge. There is no rule that an expert’s report which is uncontroverted and which complies with CPR PD 35 cannot be impugned in submissions and ultimately rejected by the judge. It all depends upon all of the circumstances of the case, the nature of the report itself and the purpose for which it is being used in the claim. I should also add that none of the authorities to which we were referred were dealing with experts’ reports which were inadequate in some way.
    1. As I have already mentioned, the Judge founded his reasoning upon a perceived inconsistency or ambiguity at [48] of the judgments of Lords Reed and Hodge in Kennedy v Cordia. I have set out the passage from that case and the judge’s reasoning in relation to it at [25] above. That case was one in which the pursuer who was a home carer slipped and fell on an icy path leading to a client’s house and injured her wrist. She commenced a claim against the defenders on the grounds that their assessment of the risk of home carers falling on snow or ice had been inadequate, in breach of the Management of Health and Safety at Work Regulations 1999 and had breached their common law duty of care. The pursuer had adduced evidence from a consulting engineer with qualifications and experience in health and safety at work. The evidence was accepted by the Lord Ordinary but an Extra Division of the Inner House of the Court of Session allowed the defender’s reclaiming motion, holding amongst other things that the evidence of the engineer had been impermissibly admitted and adopted. It was in this context that the Supreme Court considered the admissibility of the evidence of a “skilled witness” (in other words the evidence of an expert) and in which the dicta at [48] arose. See [38] – [56].
    1. Having considered paragraph [48], I fail to see the ambiguity upon which the Judge’s reasoning is based. If one reads that paragraph as a whole, it seems to me that their Lordships’ intention was to make clear that unless the matter is one of personal observation, an expert must explain the basis for his or her conclusion. A mere assertion by an expert is of so little weight that it is likely to be worthless. It is in that light that they quote a passage from the judgment of Wessels JA in the Coopers (South Africa) (Pty) Ltd case which supports their conclusion that an expert’s bald statement without the reasoning which leads to the conclusion is of little assistance to the court. Wessels JA makes clear that proper evaluation of the opinion can only take place if the process of reasoning which leads to the conclusion is set out. It seems to me, therefore, that in quoting Wessels JA, their Lordships were not endorsing his aside in relation to uncontroverted expert evidence and in any event, that aside is expressed only in terms of a possibility.
    1. It follows that once Kennedy v Cordia is read in that light, there is no ambiguity which needs to be resolved. It is unnecessary, therefore, to look for a solution as the Judge did. In any event, it also seems to me that the passage in the judgment of Clarke LJ in the Coopers Payen case, upon which the Judge relied, does not provide a basis for the Judge’s conclusion.
    1. Coopers Payen was a case in which the question for the judge was ultimately whether a large piece of machinery which had arrived as cargo on a ship and was being moved had toppled over because of a breach of duty by the defendant, Southampton Container Terminal Limited. Clarke LJ who gave the leading judgment, with whom Schiemann LJ and Lightman J concurred, stated that the question “had to be considered by reference to the evidence as a whole, including the eyewitness evidence and the expert evidence, all of which (like any evidence) must be considered against the probabilities” [38]. It was submitted that the judge had rejected the evidence of the joint expert in circumstances in which she should not have done so, given that he was a joint expert [39]. The expert was examined in chief by the judge and cross examined by both counsel. Amongst other things, on one of the issues, the judge preferred the evidence of an eyewitness to that of the expert.
    1. Clarke LJ addressed the matter of principle, in the following way:
“40. Mr Russell submits that it should be the rare case indeed in which it is appropriate for the Court to disregard the evidence of a single joint expert, and such a case will be limited to circumstances where the witness has failed to comply with his over-riding duty to the court or has plainly erred. He further submits that where such evidence is disregarded the Judge must give clear and cogent reasons for doing so. There is force in those submissions.
41. Mr Buckingham by contrast, summarized his relevant submissions in this regard as follows:
“i. Generally the expert’s report will be his evidence, without the need for amplification or cross-examination.
ii. However, in some circumstances it will be appropriate for the parties to have the opportunity to cross-examine the expert; for instance, as in this case, where the report was produced very late and the expert has not considered all the written questions that had been put to him.
iii.The report and the expert’s oral evidence, if applicable, is then the evidence of the expert.
iv.This evidence must then be weighed in the balance with the other evidence in the case and the judge will come to a conclusion based upon all the evidence.
v.The principles set out by Lord Woolf in Peet v Mid-Kent Healthcare Trust are directed at the first three of those points. The case does not establish that the evidence of the expert must then be accepted by the court. The court must take its own view of the expert evidence in the light of all the other evidence.
I would accept those submissions, as I think Mr Russell did, in the course of his oral argument. I would add these further observations.
42. All depends upon the circumstances of the particular case. For example, the joint expert may be the only witness on a particular topic, as for instance where the facts on which he expresses an opinion are agreed. In such circumstances it is difficult to envisage a case in which it would be appropriate to decide this case on the basis that the expert’s opinion was wrong. More often, however, the expert’s opinion will be only part of the evidence in the case. For example, the assumptions upon which the expert gave his opinion may prove to be incorrect by the time the judge has heard all the evidence of fact. In that event the opinion of the expert may no longer be relevant, although it is to be hoped that all relevant assumptions of fact will be put to the expert because the court will or may otherwise be left without expert evidence on what may be a significant question in the case. However, at the end of the trial the duty of the court is to apply the burden of proof and to find the facts having regard to all the evidence in the case, which will or may include both evidence of fact and evidence of opinion which may interrelate.”
    1. I agree with Mr Stevens that when stating that where a joint expert is the only witness on a topic and the facts on which he expresses his opinion are agreed, it is difficult to envisage a case in which it would be appropriate to decide the case on the basis that the expert’s opinion was wrong, Clarke LJ was not addressing the situation which faced Judge Truman here. There is no suggestion that he had in mind an expert’s report which was a bare ipse dixit, nor was he considering the situation in which the expert’s report did not deal with all the relevant issues, the expert’s conclusion was unsubstantiated by the reasoning or the reasoning was inadequate or incomplete. It cannot be assumed, therefore, that Clarke LJ’s dicta were intended to cover an expert’s report of that kind. It seems to me, therefore, that his conclusions do not take this matter much further forward and cannot operate as a springboard for the Judge’s conclusions.
    1. The same is true of the passage in the judgment of Lightman J in that case, at [67] to which Mr Weir referred us. Lightman J stated as follows:
“Where a single expert gives evidence on an issue of fact on which no direct evidence is called, for example as to valuation, then subject to the need to evaluate his evidence in the light of his answers in cross-examination his evidence is likely to prove compelling. Only in exceptional circumstances may the Judge depart from it and then for a good reason which he must fully explain. . . “
    1. It is also important to note that at the end of the same paragraph, to which I have referred, Clarke LJ stated that at the end of the trial it is the duty of the court to apply the burden of proof and to find the facts having regard to all the evidence in the case which may include both evidence of fact and evidence of opinion which may interrelate. Such a proposition is hardly controversial. It seems to me that he was considering the exercise of the normal judicial function, in relation to all of the evidence before a judge.
    1. In my judgment, for all the reasons I have mentioned, therefore, this passage in Clarke LJ’s judgment provides no support for the contention that in all circumstances, the court is bound to accept uncontroverted expert evidence which complies with CPR PD 35.
    1. I should add that, in principle, I do not dissent from Clarke LJ’s conclusions. If the report of a joint expert covers the relevant issues and the conclusion is supported by logical reasoning and it is the only evidence on the topic, it is difficult to envisage a situation in which it would be appropriate to decide that it is wrong. That does not mean that such circumstances may not exist. After all, both sides will have instructed the expert. As Clarke LJ pointed out, it all depends on the circumstances.
    1. In any event, in my judgment, Judge Truman did not decide that Professor Pennington’s report was “wrong” in the sense of expressly rejecting his conclusion. She decided that the report was insufficient to satisfy the burden of proof in relation to causation which fell upon Mr Griffiths because of its deficiencies, which she set out.
    1. We were also referred to a number of criminal cases which were concerned with the treatment of expert evidence by a jury in support of the contention that uncontroverted expert evidence does not engage the judicial function. I have to say that I did not find them of great assistance. They raise different considerations and are focused on the role of the jury in a criminal trial. Some analogies can be drawn, however, and I will consider them briefly.
    1. The first criminal case in time was R v Matheson [1958] 1 WLR 474 and the second was R v Byrne [1960] 2 QB 396. They were both murder cases in which a defence of diminished responsibility was raised. In R v Matheson the jury rejected the unchallenged evidence of three doctors to the effect that the defendant was suffering from an abnormality of mind so as to substantially impair his mental responsibility. They had been cross-examined but their opinions were not challenged, nor were the facts disputed. Lord Goddard CJ gave the judgment of the Court of Appeal, Criminal Division. It was held that the verdict was unsupported by evidence and must be set aside. Lord Goddard stated at 478 that “if the doctors’ evidence is unchallenged and there is no other on this issue, a verdict contrary to their opinion would not be “a true verdict in accordance with their evidence”.
    1. In R v Byrne, Lord Goddard stated at 403 that medical evidence was of importance to the question of whether the defendant was suffering from an abnormality of mind, but that the jury was entitled to take into account all the evidence and were not bound to accept the expert medical evidence “if there is other material before them which, in their good judgment, conflicts with it and outweighs it”.
    1. Both authorities were quoted and considered in the third case which was R v Brennan [2015] 1 WLR 2060. In that case the Court of Appeal, Criminal Division held that where a defendant charged with murder relied upon the defence of diminished responsibility which was supported by uncontradicted expert evidence, the trial judge should withdraw the charge of murder from the jury at the close of the evidence, notwithstanding that the defence was contested by the Crown, if in his considered view, on the evidence as a whole, no properly directed jury could properly have convicted of murder.
    1. Davis LJ handed down the judgment of the court. He noted that there were two potentially conflicting principles, the first being that criminal trials are decided by juries and not experts who decide the case on the entirety of the evidence and the second being that juries must base their conclusions on the evidence ([43]). He went on:
“44. There can, as we see it, be no room for departure from so fundamental a principle as the second principle. It reflects the very essence of the jury system and of a just and fair trial. But the first principle, whilst most important and undoubtedly descriptive of the general position, is also capable, as it seems to us, of admitting of degree of qualification in a suitably exceptional case. Clearly no difficulty arises (normally) where there is a dispute as to the expert evidence. The jury decides. But suppose, for example, a matter arises falling exclusively within the domain of scientific expertise; suppose, too, that all the well-qualified experts instructed on that particular matter are agreed as to the correct conclusion and no challenge is made to such conclusion. Can it really be said that the jury nevertheless can properly depart from the experts on that particular matter, simply on the basis that it is to be said, by way of mantra, that the ultimate conclusion is always for the jury? We would suggest not. Where there simply is no rational or proper basis for departing from uncontradicted and unchallenged expert evidence then juries may not do so.
45. In the Bench Book previously issued by the Judicial Studies Board, the specimen direction then published with regard to expert evidence suggested, among other things, that juries were not bound to accept an expert witness’s opinion – of itself, a correct and wholly unexceptional proposition – and were free to reject it: even if it was agreed or unchallenged evidence. This latter part may be queried; at all events as an unqualified general proposition. In our view, the position is more accurately stated in the standard directions in the Crown Court Bench Book subsequently issued by the Judicial Studies Board in 2010 (the Judicial Studies Board Crown Court Bench Book: Directing the Jury (March 2010)). That suggests a direction of this kind (after the usual directions and appropriate stress on the need for a jury to consider all the evidence) where the expert evidence on a particular topic is agreed: “Where, as here, there is no dispute about findings made by an expert you would no doubt wish to give effect to them, although you are not bound to do so if you see good reason to reject them.” In our view, if we may respectfully say so, that is altogether a more acceptable approach. It is the more acceptable because it acknowledges that if unchallenged expert evidence on a particular point calling for such expertise is to be rejected by a jury then it must be rejected for reason. “
    1. It seems to me that neither Davis LJ’s conclusions, nor those of Lord Goddard, are controversial or surprising. The jury must decide a case upon all the evidence in just the same way as a judge in a civil trial. Furthermore, where there is expert evidence which is within the domain of scientific expertise and no challenge is made to it, and there is no rational or proper basis for departing from it, the jury may not do so. In the same way, it is hard to envisage the circumstances in which it would be appropriate for a judge to do so. However, that does not mean that there is a strict rule that uncontroverted evidence must be accepted at face value whatever it says. As Davis LJ noted at [45] of his judgment, the then most recent Crown Court Bench Book stated that where there was no dispute about the findings of an expert, the jury is likely to wish to give effect to them but was not bound to do so if there was good reason to reject them. As Davis LJ stated, this is consistent with the principle that if unchallenged expert evidence is to be rejected then it must be rejected for a reason.
    1. Rather than support the contention that there is a bright line between controverted and uncontroverted expert evidence, it seems to me that Davis LJ’s judgment supports a more nuanced approach. Even in a criminal trial, the jury may reject uncontroverted expert evidence where there is reason to do so. That approach is consistent with the dictum of Hickinbottom LJ in the civil context in Whiting v First/Keolis Transpennine Ltd [2018] EWCA Civ 4 at [34] where he stated as follows:
“Whilst, as Stuart-Smith LJ said in Liddell v Middleton [1996] PIQR P36 at page P43, “We do not have trial by expert in this country; we have trial by judge”, where experts are agreed on a matter within their technical expertise, a judge will only rarely reject that evidence; and should not do so without applying considerable caution and giving adequate reasons. . . “
That was a case which was concerned with the treatment of agreed expert evidence relating to an accident on the railway.
    1. Once again, it seems to me that none of these propositions supports the Judge’s conclusion. Furthermore, none of the authorities to which we have been referred have been concerned with the issue which arose here. There is no suggestion that any of the experts’ reports under consideration were deficient in any way.
    1. What of fairness? Mr Weir submitted that it is unfair only to challenge an expert’s evidence in closing submissions. He says that if a party intends to criticize an expert’s reasoning, they must avail themselves of all the means available under the CPR and that they must either put in contrary evidence and/or put the points to the expert in cross-examination. Furthermore, he says that in this case, TUI could have sought permission to put further questions to Professor Pennington pursuant to CPR Part 35. He says that a party cannot sidestep those procedures, and in particular, sidestep cross examination in order to avoid answers they do not want to hear.
    1. He relied in this regard upon Browne v Dunn (1893) 6 R 67 HL, Markem Corpn v Zipher Ltd [2005] RPC 31 and Chen v Ng [2017] UKPC 27. In Browne v Dunn, Lord Herschell LC remarked at 70:
“Now, my Lords, I cannot help saying that it seems to me to be absolutely essential to the proper conduct of a cause, where it is intended to suggest that a witness is not speaking the truth on a particular point, to direct his attention to the fact by some questions put in cross-examination showing that that imputation is intended to be made, and not to take his evidence and pass it by as a matter altogether unchallenged, and then, when it is impossible for him to explain, as perhaps he might have been able to do if such questions had been put to him, the circumstances which it is suggested indicate that the story he tells ought not to be believed, to argue that he is a witness unworthy of credit. My Lords, I have always understood that if you intend to impeach a witness you are bound, whilst he is in the box, to give him an opportunity of making any explanation which is open to him; and, as it seems to me, that is not only a rule of professional practice in the conduct of a case, but is essential to fair play and fair dealing with witnesses. Sometimes reflections have been made upon excessive cross-examination of witnesses, and it has been complained of as undue; but it seems me that a cross-examination of a witness which errs in the direction of excess may be far more fair to him than to leave him without cross-examination, and afterwards to suggest that he is not a witness of truth, I mean upon a point on which it is not otherwise perfectly clear that he has had full notice beforehand that there is an intention to impeach the credibility of the story which he is telling. Of course I do not deny for a moment that there are cases in which that notice has been so distinctly and unmistakably given, and the point upon which he is impeached, and is to be impeached, is so manifest, that it is not necessary to waste time in putting questions to him upon it. All I am saying is that it will not do to impeach the credibility of a witness upon a matter on which he has not had any opportunity of giving an explanation by reason of there having been no suggestion whatever in the course of the case that his story is not accepted.”
    1. In my judgment, neither Browne nor the subsequent cases which reiterate the same principle are relevant here. They are concerned with the circumstances in which a significant aspect of the evidence of a witness is challenged on the basis that it is untrue. If the credibility of a witness is to be impeached as a matter of fairness, he should be given the opportunity of giving an explanation. If he has not been given the opportunity, in the absence of further relevant facts, generally it is not appropriate to challenge the evidence in closing speeches.
    1. Lords Neuberger and Mance, sitting in the Privy Council in Chen, decided however, that the “decision whether to uphold a trial judge’s decision to reject a witness’s evidence on grounds which were not put to the witness must depend on the facts of the particular case. Ultimately, it must turn on the question whether the trial, viewed overall, was fair bearing in mind that the relevant issue was decided on the basis that a witness was disbelieved on grounds which were not put to him.” [54]
    1. There is no question here of the Professor being disbelieved. His credibility was not in issue. It seems to me, therefore, that this line of cases is of no assistance.
    1. Furthermore, I can see nothing which is inherently unfair in seeking to challenge expert evidence in closing submissions. It may be a high risk strategy to choose neither to adduce contrary evidence nor to seek to cross-examine the expert but there is nothing impermissible about it. The fact that TUI decided not to call their own microbiologist having been given permission to do so and failed to serve the report from their gastroenterologist in time or to obtain relief from sanctions, does not alter that. As long as the expert’s veracity is not challenged, a party may reserve its criticisms of a report until closing submissions if it chooses to do so. The defendant is entitled to submit that the case or an essential aspect of it has not been proved to the requisite standard. He cannot be prevented from doing so because some of the evidence is contained in an uncontroverted expert’s report. Furthermore, he cannot be required to file his own contrary expert’s evidence in order to enable the court to weigh the evidence. The judge cannot be prevented from considering the quality of such evidence in order to determine whether the burden of proof is satisfied just because it is uncontroverted. As Judge Truman stated, the court is not a rubber stamp. If it were otherwise, the court would be bound by an uncontroverted expert’s report which satisfied CPR PD 35, even if the conclusion was only supported by nonsense.
    1. Furthermore, the expert and the party for whom he or she has been called are not entitled to require the opposing party to give them an opportunity to make good deficiencies in their evidence by seeking permission to pose further questions or by cross-examining the expert witness whose report contains lacunae in the subject matter considered or in the reasoning. That is the effect of Mr Weir’s submissions. It is for the party who files the evidence in support of his case to make sure that all relevant matters are covered and that the content of the report is sufficient to satisfy the burden of proof on the issue to which it is directed.
    1. In this case, the closing submissions were to the effect that the Professor’s report was insufficient to enable Mr Griffiths to prove on the balance of probabilities that his illness had been caused by contaminated food or drink at the hotel. As I have already mentioned, it was not being suggested that the Professor’s report was necessarily wrong in any way – just that it did not enable Mr Griffiths to satisfy the burden of proof as to causation. As part of a fair trial, it seems to me that it was essential that Judge Truman engaged with those submissions and determined whether causation had been proved to the requisite standard. She did so quite rightly and determined that question on the evidence before her. She had cogent reasons for deciding that the burden of proof in relation to causation had not been satisfied and rejected Professor Pennington’s report accordingly. Her reasoning was set out at [18] – [22] of her judgment. She did not decide that the Professor was wrong, just that his report was insufficient to satisfy the burden in relation to causation. It is not for us, nor was it for the Judge to overturn her evaluative judgment in that regard.
    1. The position here is obviously different from that in Woolley v Essex County Council [2006] EWCA Civ 753. However, that case supports the conclusion that it is for the court to analyse an expert’s report rather than to accept it at face value. In that case, Hallett LJ (with whom Dyson and Pill LJJ concurred) held that it was incumbent on a judge to analyse an expert’s report and decide for himself whether the expert had inadvertently referred to the wrong figures. In the face of what Hallett LJ described in that case as “lack of clarity and arguably glaring inconsistency” it was not for the judge to assume that the expert had got it right. [38]
    1. It will be clear from everything that has gone before that I do not consider that there is a strict rule that prevents the court from considering the content of an expert’s report which is CPR PD 35 compliant, where it has not been challenged by way of contrary evidence and where there is no cross-examination. The approach to such evidence all depends on the circumstances. As I have already mentioned, where the evidence is that of a joint expert, which goes to the relevant issues and contains logical conclusions, it is very hard to see that it could be successfully challenged. The same must be true if there are two experts who have produced coherent reports covering the relevant issues and who are agreed. As the authorities provide, it will be rare that expert evidence should be rejected in those circumstances and cogent reasons should be given.
    1. I reiterate, however, that everything depends upon the circumstances. As the Judge stated at [33] of his judgment a court may reject a report, even where it is uncontroverted, if it is a bare ipse dixit. 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, as the Supreme Court pointed out in Kennedy v Cordia, a mere ipse dixit is all but worthless, however.
  1. It also follows that although CPR PD 35 does not state expressly that reasons are necessary in an expert’s report, save where there is a range of opinion, it seems to me that it is clear both from the judgments in Kennedy v Cordia and as a matter of common sense, that if the court is to be satisfied as to the conclusion reached, or in a case like this, 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 this case, it would not have taken much to make good the deficiencies which Judge Truman identified. If, for example, Professor Pennington had answered question 4 of the CPR Part 35 questions by adding just a few sentences explaining the range of opinions as to sources and causes of infection, the question of whether there were one or two infections, the significance of the meals eaten outside the hotel and where Professor Pennington’s opinion stood within that range or those ranges, the burden of proof may have been satisfied.