This is the second in the series of posts on the  judgment of Mr Justice Stuart-Smith in Arroyo -v-Equion Energia Limited [2016] EWHC 1699 TCC. The first looked at the issues that arose from unchecked schedules of damages. Here we look at the expert evidence.  The judge was clear in his criticisms of the experts called by the claimants in particular.  It is a judgment worth reading for litigators and experts alike.

The parties cannot agree whether a cow that is stuck in the mire will moo”

… far from investigating the historic impact of the ODC pipeline, the technical experts appear to have accepted the mantra of the lay witnesses without question and to have set out to support the mantra as being correct. That was, in my judgment, a fundamental failure in the preparation and presentation of the Claimants’ cases. … There was compelling evidence that should have caused the Claimants’ experts to reconsider their unqualified support for the Claimants’ cases, at least by the time of trial”


The experts as to Colombian law were, overall, not problematic.   The engineering and other expert evidence, however led to many adverse comments from the judge.
495.           Each side made trenchant criticisms of the other party’s experts. Some of those criticisms were well founded, and I shall refer to those I consider to have been most important. With the exception of Mr Willis (called by the Claimants on the subject of Pipeline Project Management), each expert had something to contribute and I reject the various submissions that I should discount the evidence of the expert entirely.
496.           When considering the criticisms that have been made on either side I have constantly had in mind the obligations of experts providing reports for use in contested litigation and also the extreme pressures that litigation can impose on both experts and lawyers. I have made as much allowance as possible on the basis of the information that has been made available to me about the circumstances in which the various reports were prepared. I accept without hesitation that the experts have had to confront highly unusual, if not unique, difficulties because of the remoteness, climate and security situation affecting the areas where the Claimants live. The climate has meant that visits have had to be scheduled to cover the wet and dry seasons; while the security situation has meant that visits to properties have been delayed and, when they have happened, have had to be shorter than would otherwise have been undertaken.
497.           It is also clear that the conduct of the litigation has been highly combative, with the added pressures inherent in that state of affairs. However, while making all due allowances, it is essential that proper standards of independence and expertise be maintained in combative litigation just as in any other litigation if the integrity of the court process is to be maintained.

The Claimants’ Inter-disciplinary Approach

498.           On first reading the Claimants’ experts reports, it appeared that there had been considerable co-operation between them, extending to the mutual provision of reports with the intention and effect that one expert’s expression of opinion was either supported or based upon work carried out by another. There were numerous occasions where one expert would refer to specified passages in the reports of another, apparently adopting them as an integral part of their own reasoning and opinion. Thus, for example:
i)                    Dr Card said in his first report at [1.10] {H1.1/1/7} “where appropriate I will refer to the expert reports prepared by the following Colombian Experts acting for the Claimants” and listed six colleagues (Drs Obando, Tobon, Penuela, Velez, Snr Atencio and Snr Delgado). In the course of the report he made frequent cross references, of which [10.2.15] {H1.1/1/112} is typical. There he said “The increase in sediment of the water in the natural watercourses at the property has increased the turbidity of the water and the iron content (see Expert Reports of Dr Tobon and Dr Obando) which may have an adverse effect on water quality.” Even more specific are references such as [15.3.3] at {H1.1/1/192} where, in the course of giving his opinion on the process of sedimentation on LC74 he said “Dr Tobon describes in his Expert Report that the waterlogging on the property is due to a high rate of deposition of sediment and that the most likely cause was intense soil erosion from stockpiled soil during ROW and pipeline construction. I note that Dr Tobon’s opinion appears to be consistent with witness statements given by the Claimants as well as construction workers who also describe soil erosion from stockpiled soil during ROW and pipeline construction.” This last quotation is in relation to an issue that is right at the heart of the dispute on LC74;
ii)                  Dr Tobon also said that he would refer to the expert reports of his other expert colleagues ({H7.3/3/594} at [1.6]); and he frequently did so. At [4.3] {H7.3/3/618} he summarised what he said was the evidence from videos and witness statements by saying that “the soil that was removed during the process of excavating this trench or strip of land was deposited on either side of the route, without adequate protection and without any consideration for the natural arrangements of the soil horizons… . This soil was left there, exposed, for however long the works took on each farm, in places with steep slopes (see reports by Franco Obando and Geoff Card for their observations and conclusions on the construction process) and high rainfall … . This significantly contributed to this sediment being carried towards the streams beds either by the water during rainfall events or down the slope by gravity ..” This illustrates the mutual dependency and support given by the reports of (in this instance) Dr Card, Dr Tobon and Dr Obando. Most specifically, when writing about LC50 at [] {H7.4/4/896} Dr Tobon wrote “The amount of soil accumulated in the swampy area greatly exceeds the amount of soil that could have eroded from this grassy area. This is established in paragraph 12.10 of Geoff Card’s report: “the volume of sediment in the LC50 comparative farm has a relationship 70/30 greater in LC50. But the initial sedimentation from the ROW could have adversely affected the sediment now present”. Consequently, it can be said that the damage caused to the streams, and the formation of the swampy area (SW1), are related to the construction of the pipeline.”
iii)                Dr Velez was equally specific. In his first report at [7.1] {H5.3/4/566} he said “The specific characteristics of the soils in the region are explained in detail in the reports of Dr Card and Dr Obando, and I will refer to their conclusions in my report.” Various references of increasing specificity culminated in [] at {H5.3/4/615} where, in setting out his opinion on the measures that ought to have been implemented to restore vegetation, the immediate environment and the ecology he identifies that he refers to numerous examples “given by Dr Franco Obando in his report regarding the (lack of) implementation of adequate measures of soil management. By way of example, photographs G15 and G16 in section IV of the general section of Dr Obando’s report clearly show the phenomenon of the inversion of soil layers on one of the LC properties, and paragraph VII. details the superficiality of the soil study carried out for the construction of the pipeline. …”;
iv)                In his first report, when dealing with LC39, Dr Atencio purported to quote directly from Dr Card’s report, writing “In his report, Dr Geoff Card commented ” … in general the whole extent of the ROW has been harmed by soil erosion … .” So the sediments arrived mainly from the ROW during construction of the pipeline during construction of the pipeline … .” {H11/2/210} at [].
499.           Each of these passages (which are only a very small proportion of the many examples in multiple reports) was misleading:
i)                    Before trial, the Defendant questioned the passage at [1.10] of Dr Card’s first report, asking under CPR r.35.6(3) “Please clarify whether, from the above experts, you only read the final, served version of the above reports. If you read earlier versions of the reports, please identify, by the date of the draft, the version of the reports that you read.” {H1.3/21/704}. Dr Card’s answer (which he confirmed he had read before it was sent out in his name {Day24/104:13}) was “References in my report to other expert reports are to the same final versions as were served.” Yet when he came to give evidence, Dr Card said (and I accept) that he had seen no draft reports and no final reports from the other experts when he completed his first report. All that he had was verbal discussions in the field and in the hotel (which were in Spanish, so that he had little opportunity to take notes) and possibly a few skype calls and verbal discussions with Dr Tobon before the finalisation of Dr Tobon’s report and with other experts {Day24/20:13} ff, {Day24/100:3} ff, {Day25/166:6};
ii)                  Dr Tobon said in evidence that he had seen neither a draft nor a final version of Dr Card’s report before completing his report. That evidence is all the more surprising because the purported quote from “paragraph 12.10 of Geoff Card’s report” that I have set out above does not exist in Dr Card’s first report as disclosed or in any other of Dr Card’s reports that are before the Court. Initially he said that if he was writing about something related to Dr Card or another expert’s field of expertise, he asked Leigh Day to tell him what the relevant report was so that he could refer to it, and that although the references were in his report, he did not look at any draft of any other experts’ reports before drafting his first report {Day28/19:8}. Subsequently he said that the particular quote that had been read from his report referred to field notes and what Dr Card had been saying in the field {Day28/21:22}. Later still he reaffirmed that Leigh Day had not let him see the reports of other experts {Day29/51:16}. The only possible conclusions are that (a) contrary to his evidence, Dr Tobon saw the purported quote in a draft of Dr Card’s report or (b) he was fed the passage in his own report by the legal team (out of context but with attribution) and adopted it without having seen a draft from Dr Card. I reject as incredible his explanation that the passage was based upon field notes and what Dr Card had said in the field {Day28/21:22}, since that cannot explain how he came to attribute the purported quote to a particular paragraph of a report from Dr Card. In the absence of contrary information the most likely explanation appears to be that he was fed passages but not full reports by Leigh Day and that he included them in his report without independently verifying them or their context;
iii)                The nadir came during the cross-examination of Dr Velez. He became agitated to the point of appearing angry when he denied repeatedly that he had discussed the case with the other experts {Day32/174:10}, or seen a report or draft report from any of the other experts instructed by the Claimants before drafting his report {Day32/187:11} {Day32/189:2}. When asked how he came to identify photographs G15 and G16 in Dr Obando’s report he replied “I had not seen it. I would like to reply emphatically along those lines. This is something provided by Leigh Day” and that Leigh Day had written those sentences of his report {Day32/189:21} ff. He later modified his acceptance that Leigh Day had written the sentences, explaining that Leigh Day had given him the information, that it had backed up his findings and he accepted the information he was given {Day32/190:9} ff. He was then asked to provide a schedule to identify other parts of his report which had been compiled in the same way, which he did the following day;
iv)                Dr Atencio’s report was signed off on 27 June 2013. Dr Card’s first report was signed off on 1 July 2013. Dr Atencio’s purported quote from Dr Card’s report does not appear in Dr Card’s first report. Dr Atencio said that it came from a draft report that was provided to him and the Claimants’ counsel confirmed that a draft of Dr Card’s report was sent to him at some stage. The quote does not appear in any report from Dr Card that has been disclosed.
500.           This evidence is startling in three quite different respects. First, I am driven to the conclusion that the experts stated in their reports things that were wrong and seriously misleading. I accept the evidence of the experts to whom I have referred above that they had no more than discussions in the field and in some cases by Skype but did not have the reports (or drafts of the reports) to which they referred. If that was true of them, it is probable that it applied to others of the Claimants’ technical field experts, though I accept that Dr Atencio drew on a draft report, which puts him in a different category. Second, I accept that in some cases (of which the examples I have cited from Dr Tobon and Dr Velez are two) the Claimants’ experts included in their reports statements and information which had been provided to them by the lawyers and which they did not independently verify. Third, I am unable to understand how Dr Card could have given the answer he did to the Defendant’s question under CPR r.35.6 consistently with his duty to the Court as an independent expert.
501.           The first effect of this is to cast doubt upon the integrity of the affected reports, since it is not possible to identify what is and is not properly brought into account and relied upon by the receiving expert. More broadly, it casts doubt on the integrity of the expert evidence process as a whole, since it must (on the information I have before me) have involved the Claimants’ legal team at some level as well as the experts. These are very serious drawbacks for a court that is trying to reach a just answer in heavy litigation. It is only because I have had the opportunity to watch each of the experts over many days that I feel confident in drawing the conclusion that it would be wrong simply to jettison the entirety of any expert’s evidence because of this episode. I am convinced that, although there are other criticisms to be made of individual experts to which I will refer later, all of the experts who came to court did so with the intention of expressing opinions of which they were rightly or wrongly convinced.
502.           The involvement of solicitors in the drafting of experts reports is not the sole preserve of the Claimants. The involvement of solicitors may, of course, be a necessary and proper part of organising expert evidence and it is (to my mind) inevitable that Freshfields and Counsel will have been closely involved in the preparation of the expert evidence that was served on behalf of the Defendant. However, the Claimants identified one example, which they say illustrates exactly the same problem as has arisen with their own expert evidence. Professor Montenegro and Dr Avila produced supplementary reports that were dated 21 May 2014 {H4.9/10/1704} and {H21.9/13/1827}. They are presented in identical formats and adopted near-identical structures. The language is so similar that it is quite inconceivable that the two reports have been entirely independently written. The overwhelming probability that the production of the reports involved a process of cutting and pasting is confirmed by the fact that, although Dr Avila’s report is responding to Mr Delgado’s for the Claimant and Professor Montenegro’s report is responding to Dr Obando’s, the terms of [2.4] of each report are identical: “On the individual Lead Claimants, my conclusions remain substantively unchanged by Dr Obando’s report.” {H4.9/10/1710} and {H21.9/13/1834}. To any observer with any experience of contested litigation it is apparent that the lawyers have been co-ordinating the responses (and their physical production) which is why the format and structure is the same for each report. What is not so obvious is whether either expert saw or relied upon the substance of what became the other expert’s report, since the reasons and references in each report are different. So, while I conclude that Dr Avila must have had at least the framework which is common to his and Professor Montenegro’s May 2014 reports, and that framework must have included the reference to Dr Obando in [2.4] (since there is no other reason why Dr Avila would suddenly have referred to him), I am not in a position to conclude that either Dr Avila or Professor Montenegro adopted substantive material that was fed to him by Freshfields without independently verifying and adopting it. I return to this issue at [828] when reviewing Dr Avila’s evidence later in this section {H7.4/4/978}.
505.           As with the other experts, I have reviewed all of Dr Card’s evidence since the conclusion of the trial. That review has reinforced the provisional impression that I had formed during the trial, namely that at some stage in the proceedings, doubtless influenced by the remorseless pressure imposed by the Defendant’s emerging expert evidence and by the demands of participating in large-scale litigation, Dr Card realised that his initial observations and report were inadequate to sustain the conclusions he had reached and that, being convinced that his conclusions had been just, he set about attempting to justify them. In the course of doing so, he made mistakes that are only explicable by reference to falling from the high standards that are expected of expert witnesses in major litigation. These mistakes were of four kinds. First, he became inadequately rigorous in attributing relevance or significance to evidence that he found in the mass of contemporaneous material. This led him to attempt to bolster the Claimants’ case with evidence that was, as he should have realised, not appropriate for the task e.g. his treatment of Images 3.5-3.7 in his third report. Second, he advanced quantitative evidence based upon assumptions which he was later forced to accept were ridiculous and qualitative evidence that was essentially non-expert and at times misleading e.g. in his fourth report. Third, when concessions were required of him they were either slow in coming or not forthcoming at all e.g. his clinging onto the suggestion that the inclusion of Image/2 and Image/3 in the table of notable erosion events on LC50 was simply to provide a fair and balanced record of what he had seen on the ROW. Fourth, and to my mind most serious, he gave an explanation for the production of his fifth report which was so inadequate as to be substantially untrue. I do not go so far as to say that he consciously set out to mislead the Court, since that is not an allegation that was expressly put to him or that he dealt with in the course of his evidence; but I have reached the clear conclusion on the basis of the documents and having seen him giving evidence for days that he had by then, if not before, lost those qualities of objectivity and independence of mind which are essential for an expert in contested litigation and that he had become caught up in the siege-mentality which was painfully obvious on a number of occasions (on both sides) during the trial.
506.           These findings have two consequences, each of which is serious in the context of a case where the central issue for the technical experts is the relative and absolute contributions of the ROW works and other potential sources of erosion and sedimentation on the Claimants’ properties. First, I find it impossible to place any reliance upon Dr Card’s attempted quantifications of soil loss from the ROW consequential upon the Ocensa pipeline works. The destruction of Dr Card’s fourth and fifth reports in cross-examination on this area was complete. The Claimants evidently recognised the damage that had been done as they placed little or no reliance on Dr Card’s figures in closing submissions, being driven instead to advance calculations prepared by counsel, typically on the basis of a draft report by Professor Morgan who, though he has in the past been consulted by the Defendant, was not an expert in the case. Even before then, figures were put to the Defendant’s experts on a number of occasions which differed from and effectively abandoned those in Dr Card’s reports and evidence. Second, I cannot approach Dr Card’s evidence on other matters with the implicit trust that is the privilege of experts whose objectivity and independence have not been successfully impugned.


Another expert gave evidence in relation to water quality.
643.           When confronted in cross-examination with the obvious fact that none of the results supported his conclusion in [2.5.3] Dr Tobon had no reasonable explanation for what he had said {Day29/9:14} ff. I do not interpret his reference to the results being “a headache” as meaning that he had knowingly set about misrepresenting the effect of his results in a manner that was designed to support the Claimants’ allegations. But his absence of any reasonable explanation was surprising and a reason for concern both when this example is viewed on its own and in the light of the other evidence relied upon by the Defendant under this head of criticism.
I have gone through all of the relevant parts of Dr Tobon’s written and oral evidence again before forming a view on this particular criticism, making every allowance that I can for the fact that Dr Tobon is not an experienced litigation expert and for what he says about the involvement of the Claimants’ legal team. Having watched Dr Tobon give his evidence courteously and (usually) clearly in the face of considerable (though proper) pressure and having reviewed all of the materials that I have been asked to consider in closing, I am not satisfied that Dr Tobon was guilty of knowing bias in his approach to these results; but I find that either he started with the conclusion that he intuitively thought he should reach and failed to recognise that the data contradicted that conclusion or, although he started with the data, he was subject to unconscious bias that led him to form conclusions that his scientific training should not have permitted. Whatever the precise thought processes that led to the outcome, the result was bias manifested by a willingness to express conclusions for which there was no reasonable or scientific justification.
650.           Cross-referring to other experts: I have already dealt with Dr Tobon’s referring to reports of other experts that he had not independently verified: see [498.ii)], [499.ii)], [500]-[501] above. As I have made clear, it is unacceptable for an expert to accept material in this way. Making all due allowance for Dr Tobon’s inexperience of English litigation and what appears on the available information to have been the involvement of the Claimants’ solicitors in this process, it would be wrong to conclude that Dr Tobon’s acting in this way of itself demonstrates bias. That said, the willingness to accept material which is said to come from another expert without verifying the source or the context is a worrying indication of a lack of independence and objectivity, quite apart from the fact that its prevalence makes the Court’s task much more difficult when trying to decide what is Dr Tobon’s independent view and what is not.
651.           Reliance on DVD evidence: The Defendant submits that Dr Tobon’s reference to construction DVDs is another example of his willingness to act outside his proper field of expertise {C4/4.7/355}. It cites one clear error where Dr Tobon asserted that a still taken from a DVD showed “deposition in a stream bed of soil excavated from the ROW strip during the construction of the Ocensa pipeline. The soil was deposited directly into the beds of the streams, canos and spring sources” {H7.3/3/619}. In fact the still showed a substantial sediment trap behind a gabion wall which separated it from the main course of the stream at a significant crossing, the purpose of which was to catch soil and to prevent it getting into the main stream.
652.           The most troubling point about this error is that if Dr Tobon had looked at the video from which the still was taken, it should have been obvious to him without the need for any particular expertise that the still did not show the stream bed but an area to its side. The reason why this is troubling lies in the previous head of the Defendant’s criticism, that of accepting information from others without verifying it. I am left with the choice thateither Dr Tobon had not looked at the video or his interpretation of what he saw on the video demonstrates a complete lack of understanding of what he saw. If this were the only example of citations from videos, it might be insignificant in the overall scale of things; but in his supplemental report at [10.16] he cited 28 extracts from the disclosed videos as support for his expression of opinion that “from the evidence seen in the videos examined, we can conclude that much of the sediment that built up in the streams, both on the strip traversed by the right of way, and in the water downstream of it, was deposited there during the construction of the Ocensa pipeline, or eroded from the unprotected mounds of soil deposited on each side of the ROW” {H7.5/48/1447}. I have looked at all of the videos; that exercise alone would leave me in a state of complete uncertainty about whether Dr Tobon looked at some, all or none of them. My uncertainty is increased by Dr Tobon’s evidence, when referred expressly to the passage I have just set out, that the “role of the videos here was minimal” {Day28/36:22}. That is not the sense of the passage in the supplementary report, even though its context shows that the videos were only one part of his process of considering the available evidence; and his answers in cross-examination on this point involved a downplaying of the importance of the videos that is hard to credit unless it happened to be that his reliance on them was truly minimal because he had not himself watched them.
653.           When I take into account the apparently inexplicable nature of the error in relation to {H7.3/3/619}, and Dr Tobon’s demonstrated willingness to accept information about other experts’ views and reports without verifying them, I come to the conclusion that Dr Tobon did not himself independently review and select all of the DVD evidence to which he referred and upon which he relied in his reports. It is possible that he looked at some of it, but I do not know how much; and it is possible that he himself selected some of the extracts from DVDs to which he referred; but again I do not know to what extent.
654.           This point has significant consequences for the Court’s approach to Dr Tobon’s evidence about causation of individual cases because he relied upon video evidence in support of his views on causation on each individual stream on each property {Day28/39:17}. The relevant passage on damage to La Enix (Stream W1) on LC39 is typical, where he referred to reduction in channel width where the stream intersects the ROW and then continued “Additionally, the evidence shown in the videos available from the Defendant … [citing extracts from the videos by reference to specific points and specific durations] … show that the streams received large quantities of sediment during the construction of the pipeline, which made the channels of these streams suffer damage, like the narrowing of the channel” {H7.3/3/840} at [].
655.           I have reviewed all of the references to videos in Dr Tobon’s original report. They are too numerous to list individually here; but collectively they assert significant reliance on videos as a source of information on mechanisms and causation of damage at both a generic and individual level. In conclusion, uncertainty about whether or to what extent Dr Tobon either could or did actually rely upon the videos he cited, combined with my finding that he did not independently review and select all of the DVD evidence to which he referred and on which he relied casts a significant shadow over his evidence on causation and over his reliability as an expert.
The judge then considered passages that the expert had cited from academic articles.
659.           This episode gives rise to two criticisms of Dr Tobon, which I find to be justified and serious. The first is that excluding the omitted words was deliberate and was done in the knowledge that they were material to the Claimants’ case. I reach this conclusion because their exclusion cannot have been accidental when it is plain that Dr Tobon started with the entire quote from the article; and because Dr Tobon knew enough about the Claimants’ case to understand their materiality. This criticism is serious; but the second criticism is much more severe.
660.           I formed the provisional view when hearing and watching Dr Tobon give his evidence that the explanation he gave at {Day29/139:21} ff was not merely absurd but that Dr Tobon knew that it was. The only point in its favour is that he did not italicise the passage, which he says he would do if quoting directly. But the evidence in support of my finding that he did quote directly is overwhelming and, even when subject to the pressures of being cross-examined, he must have been able to see that the passage was a direct quote even if he had forgotten about the existence that particular paragraph altogether since including it in his report. He asserted positively that what appeared in his report was his own work and represented his summary of the underlying papers. Having reviewed his evidence again, I find myself driven to the conclusion that he knew that evidence to be untrue for two main reasons: first, the evidence is so palpably wrong as to be absurd; and second, there can have been no reason either for him to have reconstructed events to such an absurd conclusion or (which is what he appeared to be asserting) to have a recollection (albeit mistaken) of what he was saying. Before finally reaching this conclusion I have compared my reaction to this passage of Dr Tobon’s evidence with my reaction to Dr. Avila’s in apparently similar circumstances see [777] below. The witnesses were different and the facts not identical; and in the end, after trying to weigh all of the features of each witness and their evidence, my conclusions are and remain different.


  1. The agronomy experts were Dr Velez for the Claimants and Dr Uribe for the Defendant. For present purposes agronomy may be understood as being the science of soil management and its impact upon crop and vegetation production. As such, the agronomy evidence focussed on the land and agricultural management practices adopted by the Claimants and their impact with time on crop production; and on the potential impact of the Ocensa pipeline on the Claimants’ farming activities, the management of their farms, and the productivity of their farms over time.
  2. I have already referred to the difficulties that emerged from the Claimants’ experts’ “interdisciplinary approach” at [498] above. The Defendant provided a detailed critique of the application of those difficulties to Dr Velez’ evidence in its closing submissions at {C4/4.7/502} at [1]-[10]. It is a serious indictment of the preparation of an expert’s written evidence and, is in my judgment, fully made out. Specifically, the prevalence of references in Dr Velez’ first report to other experts’ reports which he had accepted on the say-so of others (itemised at {H5.7/26/1842}) is a direct and extensive contradiction of his expert’s declaration that he had not included anything in his report that had been suggested to him by others without forming his own independent view of the matter. I also accept the Defendant’s submission that Dr Velez’ second report appears to be stylistically different from his first in a way that suggests the input of lawyers. While recognising that I have only read his reports in translation and that Dr Velez did not provide for his second report a document similar to {H5.7/26/1842}, this apparent stylistic divergence adds to the uncertainty about what parts of his reports are truly his work and what was provided to him by others. This uncertainty is particularly acute in relation to the many parts of his reports where Dr Velez appeared to express clear opinions on causation of damage to the Claimants’ land, for the simple reason that Dr Velez gave evidence (which I accept) that:

“I also repeatedly said to Leigh Day, I said that what I discovered under consequences had to be backed up by experts in those areas of expertise where I’m not an expert, so I needed scientific back-up of what I discovered under consequences. So impact and cause, the experts whose area of expertise is to determine impact and cause had to back up my findings under consequences. Leigh Day assured me that there was scientific back-up under impact and cause for what I discovered under consequences” {Day33/9:5}

  1. In these circumstances, I have concluded that it is not safe to rely upon passages in Dr Velez’ reports where he appears to state opinions on causation, because I can have no confidence that they reflect his own expert opinion.
  2. The prevalence and seriousness of these failures in the manner of preparing Dr Velez’s reports and (just as importantly) the failure to disclose clearly what had happened might easily have led to the wholesale rejection of Dr Velez’ evidence but for the fact that, when he came to give evidence, Dr Velez was clear and transparent in his answers and, when left to his own areas of expertise, a very impressive and highly expert witness. What is more, once it became possible to identify those parts of his evidence that were genuinely his, it became clear that there was a substantial measure of agreement between Dr Velez and Dr Uribe.


817.           Each side called experts whose distinguished CVs suggested that they were fully competent to assist the Court. Each side submitted that the evidence of the other side’s expert could not be relied on. Neither side’s submission was persuasive.
818.           The Claimants called Dr Delgado, a veterinary surgeon and expert in livestock production, who specialises in tropical cattle production and has worked in the Bajo Cauca region of Antioquia since 1981. He has many years of experience of giving advice to cattle producers of all sizes and was selected by the University of Antioquia as professor to train students of livestock production in the area of animal reproduction. The Defendant called Dr Avila, who has practical, academic and governmental experience over many years and is just as highly qualified as Dr Delgado. The main difference between the experience of the two experts is that Dr Avila’s work in the field has generally been in the department of Casanare, and he divides his time between Casanare and Bogota. Casanare includes the Eastern Plains of Colombia and has various types of topography from steep mountains to flat plains. I accept his evidence that the Eastern Plains has all of the production systems that have been analysed by the Court; but there can be no doubt that Dr Delgado has an intimate knowledge of the Antioquia region as a result of working with cattle breeders and farmers that Dr Avila lacks. This does not, however, render Dr Delgado’s evidence impervious to criticism, even when it comes to local practices.
819.           The Defendant’s overarching attack on Dr Delgado starts with his references to other reports, where his written evidence epitomises the problems described at [498] ff. Three examples illustrate the problem, two referring to Dr Card and one to Dr Obando:
i)                    At {H20.3/3/510} referring to LC39 and giving an outline introduction to his case, Dr Delgado wrote “See the report by Geoff Card for information on the topography of the farm” thereby indicating that he adopted that information. But in evidence he said that he had not considered the parts of Dr Card’s report which dealt with the topography of the farm {Day49/13:13};
ii)                  At {H20.3/3/521} (again referring to LC39) at [5.2.3] and [5.2.4] he wrote “As the expert GC explained in his expert report (numeral 4.13 to 4.27), during the construction of the Ocensa pipeline, the practices for preventing erosion in ground with high slopes were not taken into account, … .” and “The expert Dr Card notes in his report that: The remains of an anti-erosion matting were identified on the property of Claimant 39, but it was severely deteriorated and absent in areas which are now subject to continuous erosion.” Dr Card’s disclosed report did not have any paragraphs with those numbers that said what Dr Delgado described. But Dr Delgado said that he had seen such a report from Dr Card in which he stated that he had seen anti-erosion matting on LC39 {Day49/17:8}. This was material as Dr Card’s disclosed report said that erosion matting was not found during his inspections {H1.1/1/166};
iii)                At {H20.3/3/525} (again referring to LC39) at [] he wrote that in his experience he had not seen the degree of erosion observed on the Claimant’s property and “I refer to the report provided by the expert Franco Obando regarding the types of erosion.” But in his oral evidence Dr Delgado said that the reference to the report “is not a report written by Obando, it is the result of an interaction with him in the field, because I haven’t seen [Dr Obando’s] report” {Day49/20:16}, cf {Day49/21:22}.
820.           Dr Delgado’s evidence about what he had and had not seen from other experts was inconsistent, confused and confusing. On Day 49 he said that he had reviewed the reports of Dr Card, Dr Tobon and Dr Velez and had drawn his conclusions from reading them: “Leigh Day or nobody told me I had to put this in or that in.” {Day49/32:10}. Yet on Day 50, in answer to questions from the Court, he said that “I did have available to me parts of these reports” (emphasis added) while maintaining that he had read them and made his selections from them {Day50/22:11}. A short while later in answer to a question from the Court he confirmed that he was not always sent the whole of his fellow experts’ reports, but what happened on occasions was that he had a particular area where he felt he needed information, and he would then ask for the relevant part of his fellow experts’ report which would deal with the information {Day50/24:2}.
821.           Between receipt of Dr Delgado’s report and his coming to give evidence, the Defendant had attempted to achieve clarity on this issue by asking, pursuant to CPR 35.6 “The documents you identify as those which you relied upon in order to prepare your report do not include copies of any reports or other documents prepared by other experts engaged by the Claimants. Please identify which draft reports and other documents you reviewed for each expert, by reference to date” {H20.4/9/851}. Dr Delgado’s reply was “the types of allegations I am instructed to analyse require an understanding of interdisciplinary issues. As part of my instructions, I was provided with preliminary findings of some of the other Claimant experts.. I confirm that my findings in my report of June 2013 are based entirely on my own observations, investigations and analyses in the expert discipline of veterinary science. To the extent that there are any errors in my own report with respect to paragraph references within the reports of other experts, I have clarified the same in the table below: …”. He then set out a table with two columns entitled (a) “Paragraph of my report/reference to [other Claimant expert]” and (b) “Correct paragraph reference within [other Claimant expert’s report]”. The table had three sections, referring in column (b) to the disclosed reports of Dr Card, Dr Tobon and Dr Velez respectively.
822.           This answer, for which Dr Delgado must take at least a measure of responsibility, was unsatisfactory in a number of respects:
i)                    It did not answer the question because it did not identify which draft reports he had reviewed from the other experts. On the basis of his evidence at trial, as summarised above, he should at least have identified that he had been referring to draft reports, even if the lawyers had required him to take a point on privilege or otherwise so that he transparently declined to identify the particular draft reports without a ruling from the Court;
ii)                  By referring to being provided “with preliminary findings of some of the other Claimant experts” it implied that he had not been provided with draft reports or parts of draft reports, which was contrary to the evidence he subsequently gave at {Day50/22:11} ff;
iii)                The answer then went further by implying (by the tables) that he had in fact been referring to the disclosed reports, which he and the lawyers who assisted him with the preparation of the answer, must have known to be inaccurate.
823.           In his oral evidence Dr Delgado maintained that the form of his CPR 35.6 answer was not provided to him by the lawyers and that it was his answer {Day49/27:10}. As I have made clear elsewhere, there would be nothing reprehensible in the Claimants’ lawyers assisting a Colombian expert in the proper presentation of answers to questions submitted under CPR 35.6 – in fact, I would expect them to do so. To that extent I agree with the Defendant’s submission that Dr Delgado’s answer that the form of the answer was not provided to him is implausible. However, I do not consider that I would be justified in simply rejecting it out of hand. That is not, however, the end of the matter, because even if the answer was all Dr Delgado’s own work, it should have been reviewed by the lawyers before going out and any review should have identified that the answer was unsatisfactory. It is for that reason that I said above that Dr Delgado must bear at least a measure of responsibility: on the information available to me, the lawyers having conduct of the case and responsibility for the presentation of the Claimants’ expert evidence must also bear a measure. I cannot reach a valid conclusion about precisely what measure is the responsibility of the expert and what is the responsibility of the lawyers. The conclusion I can and do reach, however, is that Dr Delgado’s evidence in his first report’s reference to other Claimant experts and in his CPR 35.6 answer lacks transparency and is in places frankly misleading; and that his evidence at trial about how the references in his report came to be made was unsatisfactory in that it was neither clear nor consistent. However, because it is not clear precisely how this unsatisfactory state of affairs came about, I do not consider that it would be right to go further than I went in [500] above when considering the problem as it affected other experts. Taken on its own, this criticism requires the Court to be astute to determine what is or is not an expression of Dr Delgado’s own observations or opinions; but it does not require the wholesale discounting of his evidence provided the Court is satisfied that the evidence in question is genuinely Dr Delgado’s and is within his proper sphere of expertise.
824.           The second strand of the Defendant’s attack on the overall reliability of Dr Delgado involves an allegation that he was prepared merely to rubber-stamp claims made by the Claimants {C4/4.7/553}. As my findings in relation to individual cases will make clear, I do not accept all of his evidence; and there are occasions when I find it surprising that he gave claims the support he did. The example cited by the Defendant of Dr Delgado supporting an annual investment of 4 days to maintain a 100m length of post and barbed wire fence is an example of evidence that is not simply insupportable but surprising {Day50/43:6}. But, while I suspect that Dr Delgado was too ready to endorse claims made by the Claimants without rigorous analysis, I am not satisfied that this requires his evidence as a whole to be down-graded as “unreliable”. The Defendant’s proper interests are suitably protected by close attention to individual assertions made by Dr Delgado on a case by case basis. Similarly, although Dr Delgado frequently made statements in his reports which appear to be opinions on causation that are outside his proper sphere of expertise, the limitations of his expertise are clear and the Court is well able to identify evidence that is outside its proper limits without applying a wholesale downgrading of his evidence as “unreliable”.
825.           The third strand is more troubling and is the identification of passages in Dr Delgado’s report where he appears to neglect information that was available to him (and was adverse to the Claimants’ case) when expressing unqualified support for individual claims. The three examples cited by the Defendant are:
i)                    In relation to LC39’s pasture management, at [8.1]-[8.3] {H20.3/3/533} Dr Delgado gave as his conclusion that the construction of the Ocensa pipeline on LC39 affected Snr Sequeda’s agricultural activity due to the deterioration of the water sources for the cattle, the decrease in pasturing areas due to erosion and the formation of swampy areas; and he stated that “no activity by the Claimant was observed that could cause the damage observed at the farm of LC39.” He did not, either in expressing his opinion or in recording the material matters on which he relied, refer to a conversation which he had with Snr Sequeda, in the course of which Snr Sequeda told Dr Delgado that before the pipeline he would leave his cattle on pasture for up to three months, depending on the quantity of cattle, and would then let the pasture rest for between fifteen days and a month, and Dr Delgado expressed clear concerns that this was an inadequate period of rest {H24.2/207.2/1015.114}. His concerns were because of the adverse effects of overgrazing and lack of recovery time for the pasture, and they were not mentioned in his report in relation to LC39. In the course of his conversation, referring to those concerns, Dr Delgado had said “that will not be in the document”, which most naturally refers to the document that he would be producing (i.e. his report) {H24.2/207.2/1015.116}. On any view of what precisely Dr Delgado meant by this comment, it suggests that the adverse information would not see the light of day, which is not satisfactory;
ii)                  Dr Delgado supported LC54’s claim for 11.5 cattle going lame and being replaced, which figure derives from the 2012 Statement of Loss at [42]-[43] {B4.1/23/273}. The Statement of Loss specifies that this claim applies every year from 1996. Dr Delgado’s report referred to [170] of Snr Mesa’s witness statement, which did not specify a period for the loss {H20.3/3/565}; and his report did not state the period to which he was referring. At the same time, Dr Delgado did not refer to the conversation he had with Snr Mesa in 2012 where Snr Mesa told him that the cattle had started going lame “5 or 6 years ago” (i.e. from 2006 or 2007, not 1996) {H24.2/258.1/1237.28}. So, at its lowest, he failed to make clear the limitation (or possible limitation) on the claim he was endorsing;
iii)                Dr Delgado supported LC74’s claim to have suffered a loss of pig production on the basis that Snr Velez had to sell his pigs when he moved his house (because of damage to the water supply at the old house) as he could not build a new pen/corral at the same time as building his new house {H20.3/3/607}. This on its own would only explain the loss of claimed loss of pig production until he had time to build a new pen. Dr Delgado gave as an additional reason (which would explain a continuing loss of annual pig production) that “the current water source that he uses for domestic consumption and for the pigs does not have sufficient availability of water to sustain the same number of pigs, so he can only keep 1 or 2 pigs, which he currently uses for personal consumption.” This explanation was inconsistent with what Snr Velez told him in interview, which was that his pigs had roamed loose, to which Dr Delgado’s reaction had been that pigs that are loose walk about and drink water “from wherever they feel like it” {H24.2/301.2/1432}; nor did Dr Delgado mention that Snr Velez had told him in the same interview that he now kept the same number of pigs as before the pipeline {H24.2/301.2/1437}. The adverse implications of both these items of information for Snr Velez’ claim would have been clear to Dr Delgado.
826.           Taken together, these three examples provide a concerning picture of an expert who is not suitably rigorous in reporting all material evidence, whether it supports or is adverse to his opinion. This makes the Court’s job more difficult because it cannot assume that all relevant material has been provided by the expert to enable his opinions to be suitably audited and tested. However, because of the allocation of enormous resources by the parties to this litigation, the Court can have a measure of confidence that material omissions have by and large been identified and raised in cross-examination and closing submissions. Therefore, while accepting the substance of the Defendant’s submission that the Court cannot rely upon Dr Delgado to have brought forward all relevant material in his report, this difficulty can best be dealt with in the context of individual cases.
827.           Taking the strands of the Defendant’s submission together, I am satisfied that there is substance in each strand of complaint and that, taken together, they require the Court to be cautious in its approach to Dr Delgado’s evidence when his reports express views on causation or make (express or implied) assertions that there is no evidence contrary to the view he is expressing. To that extent the Defendant has demonstrated areas of unreliability in his evidence. However, the Defendant has not persuaded me that his evidence as a whole should be regarded as unreliable so as to be discounted generally. Lest there be any doubt, I would be much more critical of Dr Delgado if he had been an English expert or an expert who was fully familiar with English litigation’s requirements of experts; and I bear in mind that I am not able to reach a valid conclusion on present evidence about precisely where responsibility lies for the defaults that have been identified by the Defendant.
886.           The Claimants called Mr Willis, ostensibly as an expert in pipeline project management. As was made painfully clear in the course of his cross-examination, he was no such thing, not least because he had never been the project manager of a construction project during his career {Day52/106:2}. His report, as originally provided and subsequently amended, was largely used as a vehicle to rehearse the Claimants’ case; but it did not advance it. By the end of a further immaculate cross-examination by Mr Lewis, there was nothing left that could properly be called expert opinion evidence from Mr Willis upon which the Claimants could properly rely. The Claimants implicitly recognise this in their closing submissions, in which the only observation they make is that Mr Willis had referred to BS6079: 1996. As Mr Willis and the Claimants recognise, this British Standard was a guide and not a code of practice {Day53/20:4}, being informative rather than prescriptive {Day53/21:18}.
887.           In these circumstances it was not necessary for the Defendant to call evidence on Pipeline Project Management of its own and it did not do so. It is also not necessary to spend any more time on the subject here other than to say that I accept the Defendant’s submissions on this discipline as set out at {C4/4.7/581}-{C4/4.7/588}. BS6079 speaks for itself. Mr Willis added no expert opinion evidence that assists the Court.


11. Note on Expert Evidence
921.           It is not necessary or desirable to try to establish a generalised pecking order among the experts. Nor is it necessary or desirable to repeat here the observations I have made in Section 10 and make in the Sections dealing with the Trial Lead Cases in detail. However, for the purposes of the larger cohort of claimants there is one feature of the expert evidence that needs to be highlighted for general consideration.
922.           I have previously referred to the mantra among lay witnesses that the ODC pipeline caused no damage and that all of the Claimants’ difficulties were attributable to the Ocensa pipeline. Given the nature of the ODC pipeline works, that was a mantra that should have been questioned rigorously by the experts instructed for the Claimants. In some cases the alarm bells should have rung for all of Claimants’ advisers, both technical and legal. For example, the suggestion that Snr Velez had suffered no significant damage from the ODC pipeline is evidently highly dubious even without any reference to technical experts because of the terms of his multiple settlements with ODC. Yet, far from investigating the historic impact of the ODC pipeline, the technical experts appear to have accepted the mantra of the lay witnesses without question and to have set out to support the mantra as being correct. That was, in my judgment, a fundamental failure in the preparation and presentation of the Claimants’ cases. Even if it were a sustainable opinion that there were places where the ODC pipeline was not over-worked by the Ocensa pipeline and no material damage was observed, that could not and did not mean that a general assumption could be made that the ODC pipeline works were benign. There was compelling evidence that should have caused the Claimants’ experts to reconsider their unqualified support for the Claimants’ cases, at least by the time of trial. To take just one example, knowing that the ODC ROW on LC50 had been laid in about 1991 but was bare of vegetation in September 1995 demanded a reasoned analysis by the Claimants’ experts of the consequences of that state of affairs. There was none; and it was not until cross-examination that Dr Card acknowledged that the ODC ROW would have been a continuing source of erosion during that time.
923.           It should be clearly understood by all concerned that if other cases were brought before the English court where the Ocensa ROW followed the path of the ODC ROW, the Court would expect to see a reasoned analysis of the effects of the ODC works and the extent to which the Ocensa works made things worse. At present, because of the destruction of Dr Card’s calculations in his fourth report, there is a complete absence of reliable quantitative evidence such as the Court would normally expect to see in relation to both the ODC and the Ocensa works. That is not an evidential gap that the Court can or will fill on its own.