It’s difficult for an expert witness to tell the party paying them that their case leaks like a sieve, but it is in everybody’s best interests that they do just that

The expert witness has always enjoyed, or perhaps more accurately endured, a special position in English law: they are the only people who can give opinion evidence to a court. This calls for an expert to be impartial if they are not to risk the wrath of the court. The foundation on which opinion evidence is based breaks down the moment the expert appears to act as an advocate.

Advocacy is one part of the criticism made of Laing’s expert, Tony Caletka. Judge Wilcox commented: “He demonstrated himself to be … unreliable by reason of his uncritical acceptance of the favourable accounts put forward by Laing.” Some of his evidence was described as “fanciful” and “naive”. In short: “I sadly conclude that he has no concept of his duty to the court as an independent expert”. The judge then moves on to describe the other expert witness as “impressive … conscientious … [and] independent “.

It is always difficult for an expert whose fees are paid by a party to tell that party that they are not prepared to accept the account being given by their witnesses. But it is a message the expert has to give, and as soon as possible. Only then can lawyers and clients appreciate the potential weaknesses in their case and reconsider whether to settle the action and on what terms. If the expert waits until they are cross-examined, substantial costs and court time will have been expended.

To fulfil their duty the expert must independently research and analyse the events in question. They must therefore be willing to “revisit their earlier expressed views” when new or contrary information comes to their attention. An expert who fails to do this runs the risk that their evidence will not be accepted except where it coincides with the other party’s expert. By the time, the case is likely to be lost.

James Bessey is a partner in Hammonds