EXPERT EVIDENCE UNDER THE MICROSCOPE: THE TRIAL JUDGE CANNOT OVERTURN CONCLUSIONS OF A “UNCONTROVERTED” EXPERT: HIGH COURT DECISION TODAY
NB THIS DECISION WAS SUBSEQUENTLY OVERTURNED BY THE COURT OF APPEAL. THE COURT OF APPEAL JUDGMENT IS CONSIDERED HERE.
In Griffiths v TUI UK Ltd  EWHC 2268 (QB) Mr Justice Martin Spencer considered the question of the approach of the trial judge to “uncontroverted” expert evidence. He overturned the decision of the trial judge in favour of the defendant and entered judgment for the claimant.
“..,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 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.
THE JUDGMENT OF THE CIRCUIT JUDGE
“28. It is trite law that the burden of proof is on the claimant. It is open to a defendant to sit back and do nothing save make submissions, and if the evidence is not sufficient to satisfy a court on the balance of probabilities, a claimant will not succeed. In this case, I am not satisfied that the medical evidence shows, following Wood v TUI, that it is more likely than not that the claimant’s illness was caused by ingesting contaminated food or drink supplied by the hotel. I accept counsel for the defendant’s submissions that a number of the assertions made are bare ipse dixit. There is sometimes a huge gap in reasoning between undoubted factual matters (such as incubation periods) and the conclusion that the hotel was at fault. The court is not a rubber stamp to just accept what someone has said. When causation is clearly in issue, I do consider it incumbent on the medical experts to provide some reasoning for their conclusions. I consider that is what Kennedy v Cordia advises is required. I consider that it is necessary in this case to say why, at the least, it is considered that the pre-flight meal or the local town meal should be excluded. When both sets of pleadings raise a number of possible causes and transmission methods, it might also be thought that the expert report would set out why they would be considered less likely in this particular case. I consider that Wood v TUI has clearly said that the court cannot just draw an inference from the fact that someone was ill, and that other potential causes have to be considered and excluded. Where the report does not mention a number of the raised other possible causes, I do not think it would be appropriate, without more, to assume those other causes have been considered and discounted for some good but unspecified reason.
29. Dr Thomas and Professor Pennington are undoubtedly experienced practitioners. They may both well consider, with their years of experience, that the claimant had infective gastroenteritis caused by eating hotel food, but it seems to me that reports prepared after the Wood v TUI 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.
30. In the circumstances, I find the claimant has not proven his case and I dismiss the claim
THE CLAIMANT’S SUCCESSFUL APPEAL
The claimant’s appeal was successful. Mr Justice Spencer holding that the trial judge erred in her assessment of the “uncontroverted” evidence.
In general, where an expert’s opinion is disputed, that opinion will carry little weight if, on proper analysis, the opinion is little more than assertion on the part of the expert. That this is so was made clear by the Supreme Court in Kennedy v Cordia (Services) LLP  1WLR 597 where Lords Reed and Hodge said:
“48. An expert must explain the basis of his or her evidence when it is not personal observation or sensation; mere assertion or bare ipse dixit carries little weight, as the Lord President (Cooper) famously stated in Davie v Magistrates of Edinburgh 1953 SC 34, 40. If anything, the suggestion that an unsubstantiated ipse dixit carries little weight is understated; in our view such evidence is worthless. Wessels JA stated the matter well in the Supreme Court of South Africa (Appellate Division) in Coopers (South Africa) (Pty) Ltd v Deutsche Gesellschaft für Schädlingsbekämpfung mbH 1976 (3) SA352, 371:
“An expert’s opinion represents his reasoned conclusion based on certain facts or data, which are either common cause, or established by his own evidence or that of some other competent witness. Except possibly where it is not controverted, an expert’s bald statement of his opinion is not of any real assistance. Proper evaluation of the opinion can only be undertaken if the process of reasoning which led to the conclusion, including the premises from which the reasoning proceeds, are disclosed by the expert.”
As Lord Prosser pithily stated in Dingley v Chief Constable, Strathclyde Police 1998 SC 548, 604: “As with judicial or other opinions, what carries weight is the reasoning, not the conclusion.”
In the present case, Professor Pennington’s conclusion is said by the Defendant to come so abruptly, and with so little reasoning, and with so many issues left in the air and unresolved, that his opinion contained within that conclusion amounts to no more than bare ipse dixit. In those circumstances, it is contended that the conclusion is worthless. If that is correct, it would mean that the evidence adduced by the Claimant was never capable of proving his case on causation: before the matter ever came to trial, the Defendant could have applied for summary judgment on the basis that the Claimant’s case, taken at its highest, could not succeed. The Defendant did not do so but chose instead to allow the matter to come to trial, perhaps in the hope that cross-examination of the Claimant or his wife would undermine the factual basis for Professor Pennington’s report and conclusion. If, so, that gamble did not pay off, the learned judge saying:
“In closing, Counsel did not seek to cast aspersions on their characters. This was eminently sensible in my view as the Claimant and his wife patently came across as honest and straightforward witnesses. Counsel submitted that they might be mistaken about certain matters, but having heard from the Claimant and his wife and having considered the Defendant’s documents, I accept the evidence of the Claimant and his wife. I find that the Claimant was indeed ill and that he has proven the problems he suffered then and since. In particular, I accept the evidence of the Claimant and his wife with regard to what they ate and when, and the dates the Claimant fell ill.”
Thus, it seems to me that the factual basis for Professor Pennington’s report and the factual findings made by the judge were identical. Having thus failed to challenge the factual basis for the report, the Defendant was thrown back onto its attack on the substance of the report and its assertion that the Professor’s opinions were bare ipse dixit.
In relation to her evaluation of the judgments in Wood v TUI, it seems to me that Mr Stevens QC is right when he submitted that Judge Truman was not elevating those judgments to some special test which has no basis in law, and which she found that the Claimant had failed to satisfy, but rather, the test she was applying was no more than Burnett LJ’s dictum that, in a case such as this, the Claimant has the burden of proving that his illness was caused by eating food supplied by the hotel which was not fit for consumption, and that this is a difficult test to satisfy when there are competing causes (as there always are when the illness is contracted when on a foreign holiday) and cannot be satisfied simply by proof of the illness. However, as I commented at paragraph 15 above, it seems to me that Burnett LJ and Sir Brian Leveson P had in mind, when they stated their dicta, cases where the Claimant was seeking to prove his case from the mere fact of illness, not cases where, as here, stool samples gave evidence of the potential pathogens at work and expert evidence gave an opinion as to which of those pathogens was the actual culprit, and the most likely source of infection. Thus, I endorse the distinction between the quantitative case and the qualitative case referred to in paragraph 21 above, and in a qualitative case such as the present, where an expert says that the great majority of cases of food-borne infective gastroenteritis do not occur in outbreaks, the absence of evidence of large numbers of other guests similarly affected may be of less significance whilst, in a quantitative case, such absence of evidence will be fatal to the case’s success. In those circumstances, in my judgment there are two questions to be answered: first whether a court is obliged to accept an expert’s uncontroverted opinion even if that opinion can properly be characterised as bare ipse dixit and, if not, what are the circumstances in which a court is justified in rejecting such evidence; and, second, whether, in any event, Professor Pennington’s report could in fact properly be described as no more than bare ipse dixit entitling the learned judge to reject it despite being uncontroverted.
1. When or in what circumstances can a court reject an uncontroverted expert report?
In the extract from the judgment of Lords Reed and Hodge in Kennedy v Cordia quoted at paragraph 29 above, there is an internal inconsistency or ambiguity. On the one hand, their Lordships suggest that an unsubstantiated ipse dixit is worthless. On the other hand, they cite, with approval, Wessels JA in the South African Coopers case where he said that an expert’s bald statement of his opinion is not of any real assistance except possibly where it is not controverted. So, where it is not controverted, is it worthless or not? In my judgment, the answer is to be found, as submitted by the Claimant, in the judgment of Clarke LJ in Coopers Payen Limited v Southampton Container Terminal Limited  Lloyds Rep 331 at paragraph 42 where he said:
“… 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.”
If Mr Stevens’ test is correct, namely that, to be accepted, the expert report must be (a) complete, in the sense that it addresses all relevant issues which require to be considered, (b) sufficiently reasoned so that its conclusions can be understood, then it would be all too easy to envisage a case in which it would be appropriate to decide the case on the basis that the expert’s opinion was wrong. It seems to me that Clarke LJ must have had in mind a narrower test than this and I cannot think that, in so stating, Clarke LJ was assuming that the report would satisfy Mr Stevens’ test. Indeed, that test would mean the court rejecting Wessels JA’s proviso “except possibly where it is not controverted” in the case of a report which is a bare ipse dixit, despite the Supreme Court’s apparent approval of Wessel JA’s dictum.
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.
“Form and Content of an Expert’s Report
An expert’s report should be addressed to the court and not to the party from whom the expert has received instructions.
An expert’s report must—
(1) give details of the expert’s qualifications;
(2) give details of any literature or other material which has been relied on in making the report;
(3) contain a statement setting out the substance of all facts and instructions which are material to the opinions expressed in the report or upon which those opinions are based;
(4) make clear which of the facts stated in the report are within the expert’s own knowledge;
(5) say who carried out any examination, measurement, test or experiment which the expert has used for the report, give the qualifications of that person, and say whether or not the test or experiment has been carried out under the expert’s supervision;
(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;
(7) contain a summary of the conclusions reached;
(8) if the expert is not able to give an opinion without qualification, state the qualification; and
(9) contain a statement that the expert—
(a) understands their duty to the court, and has complied with that duty; and
(b) is aware of the requirements of Part 35, this practice direction and the Guidance for the Instruction of Experts in Civil Claims 2014.
An expert’s report must be verified by a statement of truth in the following form —
“I confirm that I have made clear which facts and matters referred to in this report are within my own knowledge and which are not. Those that are within my own knowledge I confirm to be true. The opinions I have expressed represent my true and complete professional opinions on the matters to which they refer.”
In my judgment, for an expert report to pass the threshold for acceptance as evidence in the case, it must substantially comply with the above Practice Direction. Judged against this standard, it seems clear to me that Professor Pennington’s report did comply and, indeed, the Professor may well have had the Practice Direction at the forefront of his mind when he wrote his report. Thus:
(i) The report was addressed to the court;
(ii) The report started by giving the Professor’s professional credentials;
(iii) The report set out the material he had used in compiling the report, including the Letter of Claim, the Claimant’s witness statement etc;
(iv) The report set out the nature of the expert’s instructions;
(v) The report set out the salient facts, incorporating the contents of the Discharge Report provided by Kusadasi Hospital and the test results from the stool sample;
(vi) The report considered other potential causes for the illnesses such as amoebic dysentery and viral infections before concluding that Giardia was “much more likely as a cause of gastroenteritis in this case than any of the other pathogens”;
(vii) The report considered the incubation period for Giardia, compared this to the facts, and concluded that the Claimant’s gastric illness followed the consumption of contaminated food or fluid from the hotel.
(viii) The report ended with the endorsement enjoined by Paragraph 3.2(9) of the Practice Direction;
(ix) The report contained the statement of truth in appropriate terms;
(x) Although the report did not identify in terms a range of opinion on the matters dealt with in the report, this was the subject of a Part 35 question which the Professor answered as indicated in paragraph 13 above in this judgment. Mr Stevens complained, in his submissions, that the answer to question 4) provided by the Professor was not an answer to the question at all, but I disagree and, in any event, if dissatisfied by the answer, the Defendant could have made an application to the court seeking an Order that the Professor provide an answer, but chose not to do so.
It is, in my judgment, of significance that the Practice Direction goes not just to the form, but also the content, of an expert’s report. Despite this, it is no part of the Practice Direction that an expert, in providing a summary of the conclusions reached, must set out the reasons for those conclusions and it would be harsh indeed for a court to find that, despite the terms of the Practice Direction, a report failed to meet the minimum standards required for the report to be accepted in evidence because it did not set out the reasoning leading to the conclusions. In my judgment, the law does not so require. Of course, a failure to set out the reasoning might diminish the weight to be attached to the report but, as I have stated, at this stage the weight to be attached to the report is not a consideration: that only arises once the report is controverted. It may be that, had the Defendant served controverting evidence, Professor Pennington would have expanded upon his reasoning, for example in a meeting of experts, and such reasoning would have found its way into a joint statement. As it turned out, that step never became necessary because the evidence of Professor Pennington stood alone. Nor did the Defendant seek to challenge the reasoning that might have lain behind Professor Pennington’s conclusions by calling for him to be cross-examined, as it had every right to do. In those circumstances, the court must assume that there is some reasoning which lies behind the conclusion which has been reached and summarised, and that this reasoning is not challenged.
For the above reasons, in my judgment the learned judge was not entitled to reject the report and evidence of Professor Pennington for the reasons that she did. 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.
2. Was Professor Pennington’s report bare ipse dixit or otherwise so deficient as to have entitled the court to reject it in this case?
This question does not strictly need to be answered given my ruling in relation to the first question: it is clear from that ruling that I take the view that the court below was not entitled to reject the report because of its perceived deficiencies. However, in any event, although I accept that there were serious deficiencies in Professor Pennington’s report as identified by the learned judge which might well have caused the Professor serious embarrassment had the report been controverted, it was not fair to characterise the opinion of the expert as bare ipse dixit. In particular, the Professor identified the pathogen which, in his opinion, was causative of the Claimant’s illness, he considered other potential causes which he excluded, he considered the incubation period, he considered the meals which the Claimant said he had eaten, and, on the back of that, he concluded that the hotel food and drink were to blame. It is true that he did not set out his full reasoning, nor explain how he was able to reach that conclusion when he could not exclude the possibility of there having been two infections, and I am conscious of what the Supreme Court said in Kennedy v Cordia (see paragraph 29 above). But, in that dictum, their Lordships referred to the opinion being a bare or unsubstantiated one, thus amounting to an ipse dixit. In my judgment, Professor Pennington went a long way towards substantiating his opinion by his consideration of the matters referred to above and his opinion was not a bare ipse dixit as it would have been had it been a single sentence as envisaged in paragraph 33 above. In fact, I doubt whether any report and opinion from an expert which substantially complies with the Practice Direction to CPR Part 35 could ever justifiably be characterised a mere ipse dixit.