Expert Evidence in UK Law

While some degree of consultation between experts and legal advisers is entirely proper, it is necessary that expert evidence presented to the court should be, and should be seen to be, the independent product of the expert, uninfluenced as to form or content by the exigencies of litigation. To the extent that it is not, the evidence is likely to be not only incorrect but self defeating.

It is always desirable that an expert should have no actual or apparent interest in the outcome of the proceedings in which he gives evidence, but such disinterest is not automatically a precondition to the admissibility of his evidence. In considering that question the Judge will have to weigh the alternative choices open if the expert's evidence is excluded, having regard to the overriding objective of the Civil Procedure Rules.

There are various aspects of such evidence in respect of which the Trial Judge can get the "feeling" of a case in a way in which an Appellate Court, reading the transcript, cannot. Sometimes expert witnesses display signs of partisanship in a witness box or lack of objectivity. This may or may not be obvious from the transcript, yet it may be quite plain to the Trial Judge.

It follows that, if the appellate process is to work satisfactorily, the judgment must enable the appellate court to understand why the Judge reached his decision. This does not mean that every factor which weighed with the Judge in his appraisal of the evidence has to be identified and explained. But the issues the resolution of which were vital to the Judge's conclusion should be identified and the manner in which he resolved them explained.

However, its failure to do so cannot imbue expert evidence submitted by an appellant with any greater value than it merits when considered alongside the rest of the evidence. In general, the Tribunal take the view that a country expert's opinion is to be given significant weight and if the Tribunal decides to come to a different view from an expert on key matters, proper reasons must be given.

I emphasise that in my view it will very seldom be right for a judge to reach the conclusion that views genuinely held by a competent medical expert are unreasonable. It is only where a judge can be satisfied that the body of expert opinion cannot be logically supported at all that such opinion will not provide the bench mark by reference to which the defendant's conduct falls to be assessed.

The fact that an expert has included a quote attributing it to a report which does not in fact include that quote, raises questions about the accuracy of the expert's reports in other respects.