CPR 35.3(1) stipulates that it is the duty of experts to help the court on matters within their expertise. According to the recent case of Sycurio Ltd v PCI-Pal PLC and Anor (2023) that does not include knowledge gleaned from research undertaken purely for the purpose of the action in which the expert has been retained to give evidence.

The dispute forming the subject of the case concerned the alleged breach of a patent. 

During the course of the trial, it became apparent one of the experts appointed on behalf of the claimant was unfamiliar with some of the technical issues involved.

As a result, the expert struggled to understand and answer questions in relation to some of the documents despite having addressed these in considerable detail within their report.

As it transpired, that report was produced after spending many days completing a huge amount of research before sending copious notes to the instructing solicitor who then spent months assisting in putting the draft together.

While the case does not rule out the potential for the expert to conduct some further research into the specific issues for the purpose of enhancing their existing knowledge, this does not extend to educating themselves in the specific area.

In summary:-

“An expert is not instructed for court proceedings on the basis that they believe that they have “sufficient” grasp of the matter to express a view or are able to teach themselves what they need to know in the course of preparing their evidence. They are instructed on the basis that they are a genuine expert in the relevant field, whose opinions may be relied upon and given weight by the court.”

Of course, those of us used to dealing with high value catastrophic injury claims are familiar with the need to provide even expert witnesses with detailed instructions before amending the draft report as appropriate.

It is crucial however that this process does not lead to a breach by the expert of their duty to the court by giving evidence on matters falling outside their expertise. In addition, we as solicitors should not simply assume the expert understands the requirements of CPR 35 but ensure they do.


Gemma Quinn is a senior associate in the catastrophic and large loss injury team and member of the expert subject matter group.