Stay within your expertise - you don’t become an expert by virtue of having acquired knowledge in the course of the case itself

The judgment of Mrs Justice Bacon in Sycurio Ltd v PCI-Pal PLC & Anor [2023] EWHC 2161 (Pat) contains important reminders for both experts and lawyers.

“The instructing solicitors should not simply assume that the expert will understand the requirements of CPR Pt 35 and the Practice Direction. It is their responsibility to ensure that the expert has the necessary expertise and is aware of the duties imposed on an expert witness.”

 In particular, that the expert witness must give evidence on matters which fall “within their expertise”.

During the course of the trial it transpired that one of the expert witnesses (whose qualifications in their own field were not in doubt) had written a report and gave evidence on matters that were clearly outside their field of expertise. The result was that the judge was unable to accept their evidence on any matter that fell outside their core area of expertise. “The disputed matters in the case, in so far as they concerned the expert evidence, were matters on which Mrs Penn had opined, but for which I cannot give her evidence any weight.”

The judge was very clear that, of course, experts may need to do further research to enhance their existing knowledge, but they should not give evidence on issues where they have “sought to read in and educate themselves in the relevant field for the purposes of the field in question”.

The full judgement can be found in the link below – paragraphs 8 -25 concern the expert witnesses.

Learning points:

• Stay within your field of expertise
• Lawyers should not assume that the expert understands the requirements of CPR Part 35 and the Practice Direction – they need to ensure that the experts do