British Airways Plc v Spencer  EWHC 2477 (Ch)
This case is a good illustration of the approach that the court will take in larger cases in deciding whether or not to admit expert evidence.
In looking at whether or not expert evidence should be admitted, Mr Justice Warren said,
“63. ….A judgment needs to be made in every case and, in making that judgment, it is relevant to consider whether, on the one hand, the evidence is necessary (in the sense that a decision cannot be made without it) or whether it is of very marginal relevance with the court being well able to decide the issue without it, in which case a balance has to be struck and the proportionality of its admission assessed. In striking that balance, the court should, in my judgment, be prepared to take into account disparate factors including the value of the claim, the effect of a judgment either way on the parties, who is to pay for the commissioning of the evidence on each side and the delay, if any, which the production of such evidence would entail (particularly delay which might result in the vacating of a trial date).
64. Let me get one point out of the way. CPR 35.1 refers to ‘the proceedings’… There would be nothing inconsistent in accepting that particular evidence ought to be admitted in resolving an issue within the proceedings if that issue stood alone but deciding, in the context of the proceedings as a whole, that such evidence was not reasonably required in resolving the proceedings (unless that evidence was necessary to resolve the issue).
65. Thus in Mitchell , the expert evidence was not necessary but it was, or might have turned out to be, helpful. Because the issue to which it went was central to the case and because the evidence might be conclusive, it was admitted. But if in another case a similar issue were to arise which, instead of being central, was merely peripheral, the court might take the view that the expert evidence was not reasonably required to resolve the proceedings. The balance could come down in favour of refusing to admit that evidence.
68. …the correct approach to the admissibility of the evidence. Instead, it is necessary to look at the pleaded issues and, unless and until a particular issue is excluded from consideration under CPR 3.1(2)(k) , the court must ask itself the following important questions:
(a) The first question is whether, looking at each issue, it is necessary for there to be expert evidence before that issue can be resolved. If it is necessary, rather than merely helpful, it seems to me that it must be admitted.
(b) If the evidence is not necessary, the second question is whether it would be of assistance to the court in resolving that issue. If it would be of assistance, but not necessary, then the court would be able to determine the issue without it (just as in Mitchell the court would have been able to resolve even the central issue without the expert evidence).
(c) Since, under the scenario in (b) above, the court will be able to resolve the issue without the evidence, the third question is whether, in the context of the proceedings as a whole, expert evidence on that issue is reasonably required to resolve the proceedings. In that case, the sort of questions I have identified in paragraph 63 above will fall to be taken into account. In addition, in the present case, there is the complication that a particular piece of expert evidence may go to more than one pleaded issue, or evidence necessary for one issue may need only slight expansion to cover another issue where it would be of assistance but not necessary.
69. Further, although CPR 35.1 does not refer to issues, but only to proceedings, if evidence is not reasonably required for resolving any particular issue, it is difficult to see how it could ever be reasonably required for resolving the proceedings. I therefore see a test directed at issues as a filter. That, at least, is an approach which can usefully be adopted.
Exercise of discretion
103. In my judgment, in all of the instances where actuarial evidence might be of some assistance to the court, it should be admitted and should not be excluded on grounds of proportionality or otherwise. In cases where actuarial evidence is necessary to resolve a pleaded issue, it should clearly be admitted; it should be excluded only if the issue is struck out or excluded from consideration pursuant to the court’s case management powers. In areas where the evidence would be of assistance, but not necessary, to the resolution of an issue, it should be admitted. I do not propose to set out an exhaustive list of factors, but the following point strongly in favour of admitting the evidence:
(a) A very large sum of money turns on the outcome of the case for BA. Provided that this does not result in oppression or other unfairness to the Trustees, or to a disproportionate allocation of court time, BA should be entitled to put its best case and adduce the evidence which it reasonably considers will advance that case.
(b) It is undesirable to tie the hands of the trial judge if that can sensibly be avoided. Although, of course, the discretion under CPR 35.1 is there to prevent a party simply trying to bolster its case by the inappropriate use of expert evidence, that is not, as I see it, the present case. On some aspects of the case, it is appropriate that any doubt about the amount of assistance which the court might gain is best resolved in favour of BA as the person wishing to adduce it, subject to the same proviso as just expressed.
(c) If the trial judge decides at an early stage of the proceedings that the evidence will not assist him – and he or she will be in a far better position having read into, and perhaps even commenced, the case than any unassigned case management judge – the judge will be able at that stage to decline to receive the evidence in accordance with the wide-ranging trial management powers available.
(d) The costs of the exercise will be borne by BA in any event, even if none of the evidence is eventually adduced or relied on in court. The Trustees will be at no financial risk.
104. Against that conclusion, however, it can be suggested that the result is oppressive and unfair. In my view, the only points of any substance in relation to that suggestion are these:
(a) To allow expert evidence would give BA a roving brief to commission any amount of actuarial evidence involving not only its own expert but also the Trustees’ expert in trawling through thousands of pages of documents which will be of no, or at best only the most marginal, relevance. This will be a total waste of time and cost.
(b) It will result in lengthy expert reports which, far from assisting the court, will be burdensome for the court and a waste of judicial time and energy.
(c) It would also result in undue disruption of, and pressure on, preparation for trial.
105. I do not think that there is much in those points and certainly not enough to displace the factors in favour of admitting the evidence.”