“11 A first instance judge’s assessment of, or evaluations based upon, expert evidence adduced at trial must be approached by an appellate court with similar caution. Whilst it has been said that a reconsideration of an expert’s opinion may be slightly easier than a finding of fact, because the underlying report will be in writing (see Thomson v Christie Manson & Woods Ltd[2005] EWCA Civ 555 ; [2005] PNLR 38), the same case also provides a salutary warning that, since the evaluation of expert evidence is likely to be bound up with a wider evaluation of matters of fact, an appellate court will still be very slow to intervene. At para 141 of his judgement in Thomson’s case, May LJ said: “But, even accepting that individual points such as these are amenable to judicial appellate evaluation whatever the expert opinion, no appellate court should cherry pick a few such points so as to disagree with a composite first instance decision which, in the nature of a jig-saw, depended on the interlocking of a very large number of individual pieces, each the subject of oral expert evidence which the appellate court has not heard.”
“It is a commonplace that this court will only rarely disturb a judge’s finding of fact reached after hearing oral evidence whose credibility is in issue. It may sometimes be somewhat less difficult to depart from an evaluative judgment of expert evidence, if the evidence is mainly in writing and its evaluation an intellectual process largely unaffected by personal credibility. But that is not this case…..[The judge’s] conclusions are in each instance supported by credible evidence. The existence of other evidence does not render these judgments wrong nor does it persuade me that he should have reached an opposite conclusion. ….Restating evidence and submissions which the judge rejected does not persuade me that the judge was wrong, when the judge’s conclusions were supported, as they were, by the opinions of Christie’s experts.”
“46. Without attempting to be comprehensive or prescriptive, not least because it has been said many times that what is required will depend on the nature of the case and that no universal template is possible, I would make four points which appear from the authorities and which are particularly relevant in this case. First, succinctness is as desirable in a judgment as it is in counsel’s submissions, but short judgments must be careful judgments. Second, it is not necessary to deal expressly with every point, but a judge must say enough to show that care has been taken and that the evidence as a whole has been properly considered. Which points need to be dealt with and which can be omitted itself requires an exercise of judgment. Third, the best way to demonstrate the exercise of the necessary care is to make use of ‘the building blocks of the reasoned judicial process’ by identifying the issues which need to be decided, marshalling (however briefly and without needing to recite every point) the evidence which bears on those issues, and giving reasons why the principally relevant evidence is either accepted or rejected as unreliable. Fourth, and in particular, fairness requires that a judge should deal with apparently compelling evidence, where it exists, which is contrary to the conclusion which he proposes to reach and explain why he does not accept it.”
“… there is a minimum level of reasoning that is required. The critical elements of the judge’s decision-making must be recorded, such that the parties understand why the decision was reached. I would add to this that, for obvious reasons, it is usually especially important that the losing party understands why their case was not accepted. Further, the judge should bear in mind that a judgment must be understandable not just to the parties but to an appeal court. The reasons must be “sufficiently apparent to enable the appeal court to uphold the judgment”: English v Emery at [18].”
“In English v Emery the court also recommended at [25] that, where there is a challenge based on an inadequacy of reasoning, the judge should be given an opportunity to provide additional reasons. That was reiterated by Munby LJ in Re A (Children) (Judgment: Adequacy of Reasoning)[2011] EWCA Civ 1205 ,[2012] 1 WLR 595 at [16], where he said that it was the responsibility of the advocate to draw the judge’s attention to any material omission from the judgment, including any perceived lack of reasons.”
“Stool samples in the UK identified cyclospora. Given this result, it is highly unlikely that the claimant’s gastroenteritis was caused by an unrelated pathogen. On the balance of probabilities, the enteritis was caused by cyclospora.”
“The sample tested by the reference laboratory was reported as normal, no action. It should be realised that testing for cyclospora is notoriously difficult. At the time of the claimant’s illness, the most common method for testing for the presence of cyclospora was concentrate microscopy, where the presence of only a small number of oocytes or even a single oocyte is regarded as indicative of cyclosporiasis [the disease caused by cyclospora]. The test undertaken by the reference laboratory and referred to by the solicitors for the defendant were similarly concentrate microscopy. Thus, a negative result as recorded by the reference laboratory is not necessarily absolutely confirmatory evidence of what has been described as a false positive.”
“Because laboratory technicians around the UK are not highly experienced in detecting cyclospora, UK public health authorities have designated a national reference laboratory in each country. The National Reference Laboratory for England is the Hospital for Tropical Diseases, where staff have specific experience and training in identifying the organism. The stool sample provided by the claimant was, on the balance of probabilities, one of those false positives; the local lab thought they had seen it but the more experienced lab did not identify cyclospora.”
“This is speculative and highly unlikely from a biological perspective, as oocytes will remain detectable in a stool sample for extended periods of time, far exceeding the time elapsed in confirmatory testing by the reference laboratory.”
“So it’s epidemiological, it’s to do with pragmatism, limited resources, and it allows for definition to be put in place, and it’s probable and you’re right that’s how it is. So for the court that is what the particular specimen or this particular case might be described as.”
“Infection is transmitted through consumption of food or water and is contaminated by cyclospora. Food often implicated in outbreaks include soft fruit like raspberries and salad products. The incubation period is 2 to 14 days. Given that the claimant consumed no food in Mexico other than the hotel and she will not have acquired this infection in the UK or on the flight, it is reasonable to conclude on the balance of probabilities the infection was acquired at the hotel. There has been comment on poor food hygiene. Clearly, this is a subjective opinion that cannot be verified, but may be of relevance.”
“The presence of cyclospora in the stool is accepted but if she was symptomatic before travelling it is difficult to establish the time of acquisition of cyclospora infection in Mexico, it is entirely possible, if not probable, that she acquired it under these circumstances during her numerous excursions rather than at the all-inclusive resort.” “On the other hand, if the court concludes that she did not have gastroenteritis and accepts her account of events, the possibility that cyclospora caused the symptoms on her third full day of holiday, this would not be impossible from consideration of incubation times, the range being two to 14 days, but unlikely from considering of the median incubation time, seven days. It seems there is less than a five per cent chance of cyclospora causing symptoms two to three days from exposure.”
“Deciding the most likely mode of acquisition is shrouded with problems …. The preferential mode of acquisition in rural Mexico mostly involves and association with contamination water, but this may not apply to all-inclusive resorts….Collectively this would make it difficult to conclude the hotel served its citizens food contaminated by cyclospora. There are numerous other modes of acquisition.”
“Without this information, diagnosis of the putative vehicle of the infection has to be based on a probability assessment, based on the person’s history of consumption of foods and beverages before becoming unwell, together with their activity history and scrutiny of relevant hotel records, assuming these are made available, supplemented by knowledge of pathogenic microorganisms in the immediate vicinity.”
“Although she did attend four excursions after this time, she was unwell, throughout and could not enjoy these events. Although there is a possibility she contracted her infection during these excursions and not as a result of food prior to these events, on the balance of probabilities I consider this to be extremely unlikely.”
“In my judgment, it is not for the defendant to prove what the source was, it is for the claimant to prove that it is the food and the drink, something that she has consumed, and in my judgment, for the reasons that I have set out in my judgment, the claimant has failed to do so. So, in my judgment, the claim must be dismissed.”
“So it’s epidemiological, it’s to do with pragmatism, limited resources, and it allows for definition to be put in place, and it’s probable and you’re right that’s how it is. So for the court that is what the particular specimen or this particular case might be described as.”