The immunity of expert witnesses has traditionally been deemed to be in the public interest, as their evidence should be given without fear of being sued by an unsuccessful litigant. However the recent majority ruling of the Supreme Court in Jones v Kaney  UKSC 13 has held that expert witnesses are no longer immune from suit for breach of duty (whether in contract or negligence) in relation to the evidence given in court, or the views expressed in anticipation of court proceedings.
When addressing the issue, the court made it clear that no immunity should exist, unless that immunity could be justified. The position of advocates, whose immunity had been abolished in the case of Hall v Simons  1 AC 615, was considered and the court found that the evidence did not support the claim that immunity was necessary to ensure experts were willing to appear as witnesses. Additionally, the court did not believe immunity was required to protect experts from vexatious claims by unsuccessful litigants.
In his dissenting opinion, Lord Hope highlighted that there was no firm evidence, one way or the other, of the consequences of such a decision and that claims, even when completely without merit, could prove time consuming and professionally embarrassing for an expert to defend. In addition, defining what was affected by the removal and what was not was complex and, together with Lady Hale, he suggested that the preferred approach should be to leave any reform to Parliament.
The wider implications of this judgement are not yet known, however an expert's immunity from claims in defamation, and the immunity of factual witnesses will expressly remain unaffected by the decision. It may deter any tendency for an expert to act as a 'hired gun', but equally may increase the pressure on an expert to maintain their original position for fear of being sued. Practically, however, it is likely that judgement will result in increased professional indemnity insurance premiums and fees, as experts seek to protect themselves from possible claims.