Wednesday, 17 March 2010

Expert witnesses: May we sue them?

Expert witnesses appear in many cases.  Their evidence may be decisive and, occasionally, it may devastate someone's life.  The evidence may turn out to be mistaken. 

An "expert" witness has to be accepted as such by the court and, once accepted, may give an OPINION on a matter provided that it is within his area of expertise.  An expert enjoys immunity from being sued in negligence.  This rule - established by the Court of Appeal (Civil Division) in Stanton v Callaghan [2000] QB 75 -  is based on "public policy".  In the civil case of Jones v Kaney [2010] EWHC 61 (QB) this rule has been questioned by Mr Justice Blake even though, as a matter of precedent, it bound him.  It remains to be seen whether the matter will go to the Supreme Court and, if it does, whether they will uphold the rule or sweep it to one side.  The Supreme Court might decline to hear an appeal.

In 2002, the House of Lords removed the former immunity from action enjoyed by barristers in the conduct of litigation - Arthur J S Hall v Simons [2002] 1 AC 615 but the considerations for advocates are not necessarily the same as those for witnesses.  If the Supreme Court does sweep the protection away, will the door be opened to a considerable number of claims?  That is a distinct possibility.  Is there is a case for prospective overruling to prevent such claims?  The notion of prospective overruling was raised by the House of Lords in National Westminster Bank v Spectrum Plus [2005] UKHL 41.  Of course, removing the immunity might reduce the number of persons willing to provide expert evidence.  Also, perhaps it is really in the interests of justice that a witness can give truthful evidence without fear of subsequent legal action.  It is also unclear how a change might affect criminal cases.  In a number of instances, there have been miscarriages of justice based on what was, at the time, convincing evidence given by a confident expert witness - e.g. Angela Cannings case and the Sally Clark case.


  1. A difficult one.

    It might cause experts, who were not justifiably sure of their evidence, to be more cautious about how they presented it.

    Or it might cause experts, who were not justifiably sure of their evidence, to refrain from presenting it.

    Or it might cause experts, who were not justifiably sure of their evidence, to lose their fortunes and houses.

    Any of those might be considered a benefit - if they were not justifiably sure of their evidence.

    Sadly nothing is simple. The "bottom line" is that, even if this is the best that science currently has to offer, that does not necessarily mean it is any good. Sometimes science just doesn't know. Sometimes science just doesn't know enough to know it doesn't know.

    Consider the Cleveland case.

    I think of that whenever I hear about medical expert evidence.

  2. At magistrate court level, we rarely hear expert evidence. The occasional traffic cop giving evidence is rare enough and they don't appear as expert witnesses, but witnessses of fact. But in a different context I have looked at this. The whole "expert witness" system relies on the judge ensuring the jury understand how much weight they should give to what they hear. Of course many experts are articulate and credible in a way that a "non-expert" witness may not be. But that is what the judge is there for. To sum up and ensure that jurors are not hoodwinked by the spin. Where the opinion ventures to new science, even greater care is required.

  3. And, in fact, expert witness training is all about establishing your credibility in court and nothing to do with your professional area. I have both given and analysed expert opinion and there are many, at least in my area of expertise, "non-experts", who simply shouldn't be there and, on the civil side, too many old-timers who have not really appreciated the changes in behaviour that Rules 2.2 and 35.7 impose (or the older duty of an officer of the court).

    Disclaimer - I occasionally teach ethics to post-grads whose specialisation is likely to make them expert witnesses of the future.

  4. Thanks for the comments. It is only a possibility that the rule in Stanton v Callaghan will be appealed and, if there were to be an appeal, one cannot forecast the outcome with any confidence.

    IF the Supreme Court were to overrule Stanton v Callaghan then, I would argue that they ought to do so "prospectively" (i.e. for the future only). That would prevent trawling back over old cases. Legislation would be a preferable route to removing expert witness immunity in relation to negligently formed opinion. legislation, unlike case law, is almost always prospective.

    It is essential that judges remain alert to keeping experts within their field of expertise. For example, I have no doubt that Professor Meadow was permitted to stray away from paediatrics into statistics.

    A lot has changed in the use of experts. In particular there are criminal procedure rules and civil procedure rules dealing with experts. The rules have generally made it harder to get the evidence one expert challenged by the evidence of another expert. For example, Civil Procedure Rule 35.7 challenges the idea that where both parties to a case wish to adduce expert evidence then two experts are needed. The court may direct a single joint expert. See also Criminal Procedure Rule 33.7 for similar.

    Ultimately, the "tribunal of fact" has to decide the weight to be given to an expert's evidence. The weight can vary depending on the subject-matter of the case. Where technical/scientifc knowledge is involved then the expert's opinion almost invariably seems to receive great weight. This is why it is essential that experts bring to the court's attention any areas of doubt and contrary opinion.

    Also, it is very likely that the expert will have stated his opinion on the "ultimate issue" in the case. Strictly, they should not do this in criminal cases but, in practice, it happens. For example, experts have frequently been permitted to assert that the defendant suffered from diminished responsibility.

    It's a big topic and I have no doubt that we will revisit it at some stage.