At Bar school, aspiring barristers are taught the distinction between evidence of fact and expert evidence. In their early years of practice they learn that expert witnesses are, indeed, different.
An expert's evidence given at trial is part and parcel of the expert's report, prepared beforehand. Although it can be time-consuming and difficult, if you can undo the knot that holds the report together, the whole thing can unravel and the expert can come apart in the witness box like a soggy cardboard box. Forensic victory may be one thing for the advocate but what about the clients who have put their faith in their expert and brought their case to court on the strength of the expert's opinion? What remedy do they have when their case collapses alongside their expert?
Traditionally, witnesses are immune from suit.
Public policy decrees that they should be free to give their evidence without fear or favour, and certainly without the threat of litigation if they do not perform as expected. The extent of an expert's immunity was tested in the case of Stanton v Callaghan , an action against an expert who during a without-prejudice experts' meeting dramatically changed his views from those set out in his earlier report. The Court of Appeal distinguished between an expert's report, given to advise on the merits of a claim at the outset, and a report subsequently prepared for the purposes of giving evidence at trial. The expert's immunity covered the trial report but did not protect the expert's initial advice. The court concluded that experts should hold full and frank discussions at their meetings and they should be free to make concessions, however late in the day, without fear of a subsequent negligence claim.
Does this mean that, however disastrous the expert's performance in the witness box, however great the gulf between the expert's report and the evidence on the day, and however dire the consequences, the retaining party is left high and dry without a remedy?
These questions were considered recently in Raiss v Paimano (2000) and the answer seems to be, somewhat surprisingly, 'yes'. The claimant retained the defendant surveyor to act for them as an expert in a negligence claim against a firm of surveyors, which had advised in connection with the lease of property in Covent Garden. The expert told the claimant that he had considerable experience of properties in the Covent Garden area, that he was qualified to act as an expert in the litigation and, what was more, he was on the RICS Panel of Arbitrators.
At court, the expert was cross-examined by opposing counsel, who succeeded in establishing that the expert: had no particular knowledge of property in Covent Garden, as opposed to central London in general ; was not in a position to contradict the evidence of his opposite number, whom he recognised as a Covent Garden specialist ; was not able easily to support his views that the firm of surveyors had been negligent; and was not, in fact, on the RICS Panel of Arbitrators.
Counsel for the firm of surveyors succeeded in pulling the forensic rug out from under the expert's feet. The expert's credibility was destroyed and his evidence collapsed. His performance was a disaster. Such a disaster, in fact, that the claimant was advised to drop the claim and settle the action. He did, and then immediately brought a claim against the expert. In turn, the expert claimed the protection of witness immunity, saying that the claimant's complaints related to his performance in the witness box, rather than his initial advice.
When deciding whether the disastrous expert was immune from suit, the court grappled with the distinction between evidence that was given truthfully and honestly, albeit incompetently, and evidence given dishonestly. The court acknowledged that the expert had set a trap for himself by purporting to be an RICS arbitrator. Ultimately, however, the court concluded that the immunity applied even to dishonest evidence.
The moral here is the old one: experts, check your reports carefully for fatal traps; clients, check out your experts' credentials yourself. Otherwise the other side will do it for you - in court.