The Supreme Court has today handed down a judgment which abolishes the immunity from suit for breach of duty which expert witnesses have benefited from in relation to their participation in legal proceedings for over 400 years.

In this professional negligence action, the defendant psychologist, Mrs Kaney, raised the defence of witness immunity, relying on the Court of Appeal decision in Stanton v Callaghan. She applied to strike out the claim.

Handing down judgment on 21 January 2010, Blake J held that Stanton was still good authority, was binding on him and he was required to strike out the claim. However, because he considered that a policy of blanket immunity for all witnesses was too broad, the case was certified as being suitable for a leap-frog appeal to the Supreme Court under section 12 Administration of Justice Act 1969. The Supreme Court has today allowed the appeal.  

The judgment is available at  


The claimant brought a personal injury claim following a road traffic accident. An issue arose as to whether he had suffered post traumatic stress disorder (PTSD). Mrs Kaney initially reported that the claimant had symptoms that suggested a diagnosis of PTSD. The defendant’s expert concluded that the claimant was exaggerating his symptoms.

Following a telephone conversation with the defendant’s expert, Mrs Kaney signed a joint statement which he prepared. The statement stated that she had found the claimant to be “very deceptive and deceitful in his reporting". There were several problems with the joint statement, not least that Mrs Kaney had not seen the defendant’s expert’s report at the time of the conversation, the statement didn’t reflect what she had agreed on the telephone and it was still her view that the claimant had suffered from PTSD, albeit it had been resolved.

As a result of the damaging nature of the joint statement and the inability of the claimant’s solicitors to persuade the judge that Mrs Kaney should no longer act as an expert in the proceedings, the claim was settled for considerably less than would have been the case if she had not signed the joint statement.

The claimant brought proceedings for professional negligence which were struck out because of the defendant expert immunity.

The judgment of the Supreme Court

Giving the lead judgment, Lord Phillips (Lord Hope and Lady Hale dissenting) held that:  

  • An expert witness owes a duty to their client in contract and tort to act with reasonable skill and care in accordance with section 13 of the Supply of Goods and Services Act 1982 and Hedley Byrne & Co Ltd v Heller & Partners.
  • An expert has an overriding duty to the court in accordance with CPR 35.3. Since the expert is usually instructed to perform his or her duties in accordance with the CPR, the duties to the court and the client co-exist.
  • Expert witnesses, as contrasted with witnesses of fact, choose to provide their services voluntarily and in return for payment.
  • A client relies on the expert to give skilled and expert opinion in determining whether to bring or defend proceedings, in considering settlement values and appraising the risks of proceeding to trial.
  • Every wrong ought to have a remedy unless there is a public interest exception. However, experts have traditionally been immune from suit on public interest grounds and, following the case of Stanton, that immunity extends to any pre-trial work intimately connected with the case, to the contents of a report adopted in evidence, to concessions made in an experts’ meeting/ joint statement and to anything said in court.
  • It would be wrong to presume that just because immunity exists it should be maintained. The onus is on the expert to justify why he or she should be entitled to hide behind the existing immunity.
  • Experts’ immunity has already been eroded in respect of disciplinary proceedings before professional tribunals (following Meadows v General Medical Counsel) and in respect of applications for wasted costs (Phillips v Symes (No 2)).
  • The established justifications for maintaining immunity (such as experts’ potential reluctance to provide evidence or testify, the need to ensure experts give full and frank evidence and the need to protect experts against vexatious litigants) are no longer viable.
  • Experts are likely to be more careful not to overplay their views at the outset of a case for fear of being embarrassed at a later date. This was viewed as a potentially healthy development since it ought to enable parties to take more reasonable views at the outset which should help to achieve earlier resolution.
  • Anyone providing professional services which involve a duty of care is at risk of being sued and they customarily insure against that risk. Experts should be no different.


This decision will be of interest to those insureds who provide expert opinion (whether in respect of court proceedings or beforehand) and to their insurers.

Immunity is a very unforgiving defence. It leaves the victim of even the most serious negligence without any remedy. Why should the expert who provides advice to a client, and receives payment for that service, be free from claims if their view is negligent? After all, they are doing no more than a solicitor or barrister advising as to the merits of a case.  

Will there be a flood of claims? We suspect not. The Supreme Court made several analogous references to the removal of immunity for barristers following Arthur JS Hall & Co v Simons in 2002. Although claims against barristers have occurred following that decision, the Supreme Court did not consider that this could be described as a flood of claims. The fact is that it is difficult to prove that an expert witness has been negligent, particularly in relation to what he or she says in the heat of battle in court. The expert has a duty to act with the reasonable skill and care of an expert from the relevant discipline. As long as the expert gives an independent and unbiased opinion which is within the range of reasonable expert opinions, he or she will have discharged their duty to the client and, indeed, to the court.

One expert who may be vulnerable is the jointly instructed expert. The CPR requires parties to consider jointly instructing experts to save costs. A jointly instructed expert owes contractual duties to all instructing parties. It is inevitable that one of the instructing parties will be disappointed by the expert’s view. Whereas it is difficult to persuade the court to allow a further expert to be instructed to call that opinion into question, it may be more straightforward to find an expert who is prepared to disagree with the joint expert’s view so as to act as a foundation to an allegation of negligence. Once again, however, the issue will fall down to the reasonableness of the advice/opinion but this may represent an area of vulnerability that experts ought to consider.

The insurers of experts should be aware of those astute claimants who may consider reviving old cases. There were a number of cases against barristers after the abolition of their immunity. Limitation will need to be looked at with care since the Supreme Court has not given any indication as to when the abolition of the immunity should take effect. However, we would expect any court to follow Awoyomi v Radford in which the court determined that Hall v Simons was not prospective in effect. This meant that immunity for advocates ceased to exist from the date of the negligent acts in Hall v Simons which had taken place in 1991. If Jones v Kaney is interpreted on the same basis, immunity for experts ceased to exist with effect from November 2005 when Mrs Kaney negligently signed the joint statement.