A recent case heard in the High Court in December 2016 has highlighted the importance of the role of the expert witness in clinical negligence cases and the dangers lurking for the expert who the Court concludes has been less than careful: Harris v Johnston.

The case concerned the performance of a revision C6/7 foraminectomy by a consultant neurosurgeon (Mr Francis Johnston) which involved the use of a surgical instrument, the Cobb dissector, which had unfortunately during surgery penetrated the dura and came into contact with the spinal cord, damaging it. The primary issue in the case was whether the surgery by Mr Johnston had been competently or incompetently performed. The judge (Mrs Justice Andrews) found that it had been competently performed; however, a considerable proportion of the judgment concerned the claimant’s neurosurgical expert evidence. The claimant’s expert was Mr Peter Kirkpatrick; Mr Robert Macfarlane was his opposite number for the defendant.

The primary allegation advanced at trial by the claimant was based on Mr Kirkpatrick’s expert’s opinion that it was negligent to have damaged the spinal cord with the Cobb retractor. However, the formal Defence had pleaded that the mechanism of injury to the spinal cord was by way of a Cobb dissector which had perforated the dural sac via a meningocele (which had been an unexpected finding) leading to a CSF leak and causing an injury to the cord. Mr Kirkpatrick was in fact aware that a Cobb “dissector” was a blunt instrument and that a Cobb “retractor” was a distinct instrument that was, in contrast, sharp. However, he had failed to appreciate this distinction and had proceeded through the case on the misassumption that Mr Johnston had used a sharp retractor rather than a blunt dissector. The judge described this as a “fundamental misapprehension as to how the injury was sustained” and concluded that “this mistake permeated his evidence”. She considered that, at the very least, Mr Kirkpatrick did not “read the material before him with an appropriate degree of care or asked the questions one would have expected him to ask to obtain clarification”.

However, matters worsened for Mr Kirkpatrick. As the judge stated: “Even if I were to be really generous to Mr Kirkpatrick and absolve him from any blame for failing to appreciate prior to the joint experts’ meeting that there was at least some confusion about what the instrument was, he was well aware of the possibility that he had made a mistake when he discussed the joint report with Mr Macfarlane at the experts’ meeting… Yet Mr Kirkpatrick did nothing to check if his assumption about the instrument that was used was correct. He accepted in cross-examination that he was under a duty to have done so, and that he was in breach of that duty”.

The judge was further perturbed by the expert’s insistence that, effectively, there was no way in which the injury could have occurred without negligence regardless of what instrument was used. She concluded that: “That intransigent mind set coloured his evidence throughout, and it did so in a way which was not helpful to the Court… [an expert] cannot possibly assist the Court if he does not take appropriate steps to ensure that he is giving his opinion based on the facts that are alleged, rather than on assumptions about the facts which may turn out to be completely ill-founded”.

As if that was not bad enough, the judge then latched on to the fact that the expert “had recently been criticised by Her Honour Judge Melissa Clarke in the Oxford County Court for making factual assumptions about key matters in the case (including the nature of the operation that was performed by the defendant surgeon) without taking any steps to check that his assumptions were correct” (Kneuss v BMI The Chiltern Hospital and Stuart Blagg [Case No. 2YN28735]). Andrews J. was especially troubled that it was apparent that Mr Kirkpatrick had not learned from this earlier criticism and had not done all that he could to avoid it happening again, concluding: “It beggars belief that he would allow this to happen a second time”. Ultimately, the judge concluded that these matters went “far beyond matters of credibility”.

The judge was then further critical of the expert for failing to address the issue of whether he disputed, and if so why, the presence of a meningocele referred to in the Defence (and by the defendant), both before trial and in his supplementary report served on the second day of trial at the judge’s direction. Mr Kirkpatrick in fact had advanced at trial two new theories for the mechanism of injury (both considered by Mr Macfarlane not to be feasible), essentially based on using too much force with the instrument but neither of which had been put to Mr Johnston (who had already given evidence) and neither of which had previously been advanced by the claimant.

Ultimately, the judge concluded that the defendant’s criticisms of Mr Kirkpatrick were well-founded, namely that:

i) He was evasive in his answers to fairly straightforward questions; ii) He had a tendency to change his opinion depending on his agenda; iii) He would make categorical statements, which he was then forced to qualify by adding caveats or limitations; iv) When faced with new evidence, or when forced to make concessions, he latched on to the first argument he could use to maintain the position he had initially adopted; v) He failed to give proper consideration to the factual evidence.

In addition, the judge found that Mr Kirkpatrick’s “reasoning was unreliable” and that “his general intransigence, his sloppy attention to detail and his failure to abide by his duties as an independent expert did not just lead me to question his reliability, it left me with no confidence in him”. Accordingly, the judge could not, and did not, rely on any of his evidence. This made it almost impossible for the claimant to succeed based on only the defendant expert’s evidence, and unsurprisingly the claimant lost. To add further insult to injury for Mr Kirkpatrick, the judge described Mr Macfarlane as “the model of an independent and impartial expert, balanced, fair and objective”.

An expert’s duty is set out clearly in Part 35 of the CPR and the associated Practice Direction (PD). The latter states unequivocally: “2.2 Experts should assist the court by providing objective, unbiased opinions on matters within their expertise… 2.3 Experts should consider all material facts, including those which might detract from their opinions”. The PD also refers in paragraph 1 to further guidance being found in the Guidance for the Instruction of Experts in Civil Claims 2014 at www.judiciary.gov.uk, which came into force on 1 December 2014. An important paragraph relevant to this case is paragraph 13: “Experts should take into account all material facts before them. Their reports should set out those facts and any literature or material on which they have relied in forming their opinions. They should indicate if an opinion is provisional, or qualified, or where they consider that further information is required or if, for any other reason, they are not satisfied that an opinion can be expressed finally and without qualification”; and, at paragraph 9, “Experts always owe a duty to exercise reasonable skill and care to those instructing them…

There can be little doubt, therefore, about the role of the expert and the importance of the need for an expert to be diligent and careful in their consideration of the evidence, their analysis of the case and in the opinion they reach. This case is a stark example of what may happen when an expert falls short of these requirements and the damage that may be caused both to the instructing party’s case as well, no doubt, as to the expert’s reputation. All experts should heed the judge’s criticisms, most importantly that an expert needs to ensure that he or she has considered carefully all material facts and the evidence as a whole. It is also of potential note that a subtext to the judge’s frustration in this case appears to relate to the expert being intransigent when it became apparent that he had made an error (or at least the judge had perceived the expert’s position to be irretrievably flawed). Overall, though, the case highlights the dangers that lurk for the less than careful expert, however experienced an expert they may be.

A similar form of this article was first published by LexisNexis on their website on 19.01.17.