The Supreme Court handed down its judgment in the case of Jones v Kaney [2011] UKSC 13 on 29 March 2011. The issue in this case was whether the act of preparing a joint witness statement was one in respect of which an expert witness enjoyed immunity from suit.

The appellant had been hit by a car on 14 March 2001, suffering physical and psychiatric injuries. He instructed solicitors to act for him in a claim for personal injury proceedings, and they, in turn, instructed the respondent, a clinical psychologist, to prepare a report on his psychiatric injuries in which she described that the appellant was suffering from post traumatic stress disorder (PTSD). The appellant alleged that a further joint statement prepared by the respondent for the court had been carried out negligently and that this was so damaging to his claim for damages that he felt constrained to settle it for significantly less than he might otherwise have been able to achieve.

The appellant issued proceedings for negligence against the respondent, the respondent applying for the claim to be struck out on the ground that she was immune from prosecution. Blake J in the High Court held that he was bound by the Court of Appeal’s decision in Stanton v Callaghan [2000] QB 75 to hold that the respondent was entitled to immunity from a claim in negligence in respect of preparation for trial. The appellant’s appeal against that order came directly to the Supreme Court as a point of general public importance, pursuant to section 12 of the Administration of Justice Act 1969.

Lord Phillips, giving the lead judgment of the Supreme Court, held that the immunity from suit for breach of duty (whether in contract or in negligence) that expert witnesses had enjoyed in relation to their participation in legal proceedings should be abolished. That did not extend to the absolute privilege that they enjoyed in respect of claims in defamation, and nor did it undermine the immunity of other witnesses in respect of litigation.

Phillips LJ noted that the immunity had not been challenged in the past and that it had been accepted that the immunity protecting witnesses of fact applied equally to expert witnesses. It overlapped with the wider immunity enjoyed by barristers from a claim until that was abolished as unjustifiable by the House of Lords in Arthur JS Hall and Co v Simons [2001] 1 AC 615, although advocates are still protected by absolute privilege from a claim in defamation in relation to statements made in the course of the conduct of legal proceedings.

It was not right to start with a presumption that because the immunity existed it should be maintained unless it was shown to be unjustified. The onus lay fairly and squarely on the respondent to justify the immunity behind which she sought to shelter. The primary rationale for the immunity was a concern that an expert witness might be reluctant to give evidence contrary to his client’s interest, in breach of his duty to the court, if there was a risk that this might lead his client to sue him.

In common with advocates there was no conflict between the duty to provide services to his client with reasonable skill and care, and the duty owed to the court and the evidence did not suggest that the immunity was necessary to secure an adequate supply of expert witnesses. The removal of immunity for advocates had neither diminished their readiness to perform their duty nor proliferated vexatious claims or multiplicity of actions.

No justification had thus been shown for continuing to hold expert witnesses immune from suit for breach of duty in relation to the evidence they gave in court or for the views they expressed in anticipation of court proceedings. That decision did not affect the continued enjoyment by expert witnesses of absolute privilege from claims in defamation, and nor did it undermine the longstanding immunity of other witnesses in respect of litigation.

Lord Hope and Lady Hale, dissenting, disagreed with the majority’s approach of reviewing the justification for the immunity. The rule was longstanding and the existence of a duty to a client was no reason for excluding them from the immunity available to witnesses generally. The main concern was not the effect on expert witnesses but on disappointed litigants who were liable to commence worthless but time-consuming claims against their experts. The lack of a secure principled basis for removing the immunity, of a clear dividing line between what was to be affected by the removal and what was not, and of reliable evidence to indicate what the effects might be, suggested that reform would be better left to Parliament.

The Supreme Court by a majority allowed the appeal.