The judgment of Mrs Justice Carr DBE in Cooper -v-Thameside Company Ltd  EWHC 1248 (TCC) contains an interesting, and ultimately important, consideration of the judicial approach to fact finding. It is interesting that this £6.5 million depended, primarily, on the assessment of the credibility of one witness. That witness had, apparently, not been interviewed by the defendant when it, initially, admitted liability.
“Lord Brandon disavowed the approach of Mr Sherlock Holmes as he was recorded saying to Dr Watson: “How often have I said to you that, when you have eliminated the impossible, whatever remains, however improbable, must be the truth?”
“The result has been much speculation; theories have been mooted and abandoned during the course of the trial; new theories have been advanced for the first time in the very closing stages of trial.”
The claimants home was flooded and damage worth £6.5 million. Their insurers brought a subrogated action against a construction company. It was common ground that the flood was caused by a defective Polyplumb connector in a bathroom. The defendant initially admitted liability but obtained permission to resile. The issue was whether the defendant had, in fact, installed that connected.
THE JUDICIAL APPROACH TO FACT FINDING
F. The burden of proof and the fact-finding exercise
The burden of proof lies throughout on Mr and Mrs Cooper to prove, on a balance of probabilities, that the failed Polyplumb connector was installed by Thameside or one of Thameside’s sub-contractors carrying out works under the JCT contract. For the claim to succeed it does not have to be proved why or when the Polyplumb connector was so installed, though of course issues of rationale and timing may be relevant to the question of who it was that carried out the installation. Equally, Thameside does not have to prove that some other party installed the Polyplumb connector. But if there is no possible alternative other than that Mr Johnson or someone else at Darenth or otherwise engaged by Thameside could have installed the Polyplumb connector, then that will clearly be relevant to the question of liability.
The position was well settled in Rhesa Shipping Co v Edmunds (“The Popi M”)  AC 948. There the sole question for the appellate court was whether, on the basis of the first instance judge’s primary findings of fact, the judge (and the Court of Appeal) was justified in drawing the inference that the ship was, on a balance of probabilities, lost by perils of the sea. Lord Brandon stated (at 951B-C):
“In approaching this question it is important that two matters should be borne constantly in mind. The first matter is that the burden of proving, on a balance of probabilities, that the ship was lost by perils of the sea, is and remains throughout on the shipowners. Although it is open to underwriters to suggest and seek to prove some other cause of loss, against which the ship was not insured, there is no obligation on them to do so. Moreover, if they chose to do so, there is no obligation on them to prove, even on a balance of probabilities, the truth of their alternative case.”
“The second matter is that it is always open to a court, even after the kind of prolonged inquiry with a mass of expert evidence which took place in this case, to conclude, at the end of the day, that the proximate cause of the ship’s loss, even on a balance of probabilities, remains in doubt, with the consequence that the shipowners have failed to discharge the burden of proof which lay upon them.”
a) A judge is not bound always to make a finding one way or the other. This is a point “of great importance”. The unsatisfactory state of the evidence may make this the only just course for him to take;
b) The dictum can only apply when all relevant facts are known, so that all possible explanations, except a single extremely improbable one, can properly be eliminated;
c) The legal concept of proof of a case on a balance of probabilities must be applied with common sense. If a judge concludes on a whole series of cogent grounds that the occurrence of an event is extremely improbable, a finding by him that it is nevertheless is more likely to have occurred than not, does not accord with common sense.
Subsequent and more recent cases confirm the continuing soundness of this approach. For example in O’Connor v The Pennine Acute Hospitals NHS Trust  EWCA Civ 1244 Jackson LJ stated:
“64. It is not an uncommon feature of litigation that several possible causes are suggested for the mishap which the court is investigating. If the court is able, for good reason, to dismiss causes A, B and C, it may be able to reach the conclusion that D was the effective cause. But the mere elimination of A, B and C is not of itself sufficient. The court must also stand back and, looking at all the evidence, consider whether on the balance of probabilities D is proved to be the case. See Nulty v Milton Keynes Borough Council EWCA Civ 15 at  per Toulson LJ and Graves v Brouwer  EWCA Civ 595 at  to ”.
“34. A case based on circumstantial evidence depends for its cogency on the combination of relevant circumstances and the likelihood or unlikelihood of coincidence. A party advancing it argues that the circumstances can only or most probably be accounted for by the explanation which it suggests. Consideration of such a case necessarily involves looking at the whole picture, including what gaps there are in the evidence, whether the individual factors relied upon are in themselves properly established, what factors may point away from the suggested explanation and what other explanation might fit the circumstances. As Lord Mance observed in Datec Electronics Holdings Limited v UPS Limited  UKHL 23,  1 WLR 1325, at 48 and 50, there is an inherent risk that a systematic consideration of the possibilities could become a process of elimination “leading to no more than a conclusion regarding the least unlikely cause of loss”, which was the fault identified in The Popi M. So, at the end of any such systematic analysis, the court has to stand back and ask itself the ultimate question whether it is satisfied that the suggested explanation is more likely than not to be true. The elimination of other possibilities as more implausible may well lead to that conclusion, but that will be a conclusion of fact: there is no rule of law that it must do so. I do not read any of the statements in any of the other authorities to which we were referred as intending to suggest otherwise.”
In Graves v Brouwer (supra) Tomlinson LJ (at paragraph 24) approved that statement of principle, that, provided that all possible causes are known, the ranking of those causes in terms of probability may lead to a safe conclusion that the one considered the most probable was the probable cause of the event, provided that it was not improbable.
a) The court is entitled to engage in a systematic analysis of competing theories and eliminate one in favour of the other;
b) That, in itself, may lead to the conclusion that the preferred theory is more likely than not to be true; but
c) The court must always then stand back and ask itself the ultimate question as to whether or not the preferred explanation is more likely than not to be true.
a) Mr Balola of Signature;
b) Mr Tucny of Ludek.
The documentary position has also not assisted in resolving the issues. I have been shown little to no site records, for example, to the extent that they ever existed. Nor has it been possible, for example, to identify with any particularity the timing or nature of works being carried out from any invoicing material that I have been shown.
Thameside invites me to draw adverse inferences from the failure to call these witnesses on the part of Mr and Mrs Cooper, a submission that I address in section K below. Leaving that to one side, the position is that there are many evidential lacunae. The result has been much speculation; theories have been mooted and abandoned during the course of the trial; new theories have been advanced for the first time in the very closing stages of trial.”
THE PRACTICAL CONSEQUENCES
The judge went on to find that:
The defendant’s plumber did not, in fact, fit the errant connector.
There were at least two realistic possible alternatives for the installation of the connector which did not involve the involvement of the defendant.
“ Against an incomplete evidential picture, it is ultimately the combination of the credibility of Mr Johnson as to the essence of what he did and the real possibility that another non-Darenth tradesman on site performed the highly incompetent installation that leads me to the conclusion that the case against Thameside has not been made out on a balance of probabilities.”
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