Expert Witnesses – an update

New guidance has been published in England for the instruction of expert witnesses. This guidance supplements the English Civil Procedure Rules Part 35 on Experts. We explore this new guidance and examine expert witness best practice in England, and compare the practice of expert witnesses in Scotland.

22 January 2015

New guidance has been published in England for the instruction of expert witnesses. This guidance supplements the English Civil Procedure Rules Part 35 on Experts. We explore this new guidance and examine expert witness best practice in England, and compare the practice of expert witnesses in Scotland.

Civil Procedure Rules Part 35 – Experts and Assessors

The English Civil Procedure Rules are mandatory rules which experts and those who instruct experts should be aware of. There are two key rules:

The first (Rule 35.3) is that the expert has a prevailing duty to the court, overriding any duty to the party instructing or paying the expert. Experts and those instructing experts should be aware of this duty and the guidance discussed below gives practical examples of how this duty can be tested in practice. Rule 35.10 requires the expert to record their understanding of and compliance with their duties. It also requires the expert to set out the substance of all material instructions given to them.

The second (Rule 35.4) is that an expert cannot be called, or an expert report put in evidence, without the court’s permission. A party is free to instruct an expert for their own benefit.

There is no equivalent to the above rules in Scotland.

Civil Justice Council Guidance

The Civil Justice Council has published guidance for the instruction of experts. This replaces the previous Protocol on experts and supplements the Civil Procedure Rules. The prevailing duty of an expert to the court sits alongside the expert’s other duties and obligations to their profession and client, but the duty to the court is the overriding duty. The guidance alerts experts to their other duties and how to navigate conflicting duties.

The expert owes a professional duty of reasonable skill and care to those instructing them. An expert must ensure that their work and associated costs are in proportion to the value and importance of the case. Experts must also act expeditiously and must not stray beyond matters which are material to the dispute. All their actions must be fair and the opinions which they provide must be independent.

The guidance suggests that to test the independence of their opinion and report, an expert should be comfortable that they would give the same opinion, even if instructed by the other party. An expert should confine their opinions to their area of expertise, and must self-regulate and justify the limits and extents of their expertise. It is usual for a biography of experience to be included in the expert’s report.

Experts are asked to keep matters of fact and opinion clearly separate. All material facts in their possession should be used in forming their opinion. The extent of any factual assumptions or further information required, should be made clear by the expert. If there are material facts in dispute, then experts should provide separate opinions based on the competing versions of the material facts.

As an expert owes their primary duty to the court, the court reciprocates by allowing experts to request directions from the court. Such directions can be sought if an expert requires information which they are not being provided with or has any other concern about their duties. This is usually only done after consulting those instructing the expert and formal notifications are given to the instructing party and any other party in the action.

The Scottish Position – duty to court

Scotland does not have a corresponding set of rules or guidance for the instruction of an expert. Instead, reliance is still placed on relevant case law to set out the role of an expert.

The nature and scope of an expert’s duty to a court in Scotland is unclear. In a 2006 case (Amy Whitehead’s Legal Representative v Graeme John Douglas and Another [2006] CSOH 178), Lord Carloway stated that:

“It is not at all clear that an expert, instructed by one party, has some form of duty to the court greater than any professional or other witness.”

However, in a 2009 case (BSA International SA v Irvine [2009] CSOH 77), Lord Glennie stated that:

“It has been accepted in Scotland for some time that an expert witness owes a duty to the court.”

The Scottish Position – experts value and conduct

Whether experts have an overriding duty to the court or not, the appeal case of Davie v Magistrates of Edinburgh [1953] SC 34 still provides the benchmark guidance on the value of expert opinions and on their expected conduct.

In this case, the defenders stated that their expert’s opinion must bind the court, as the pursuer had not provided a contrary expert opinion. This was firmly rejected by the judge, who noted that an expert can only provide evidence, and that it is for the court (judge or jury) to consider, weigh up and decide upon the totality of the evidence put before them.

Lord Strachan also considered the value of expert evidence and stated that:

“The value of such evidence depends upon the authority, experience and qualification of the expert and above all upon the extent to which his evidence carries conviction… The scientific opinion evidence, if intelligible, convincing and tested, becomes a factor (and often and important factor) for consideration along with the whole other evidence in the case.”

A number of the factors contained in the English guidance can be extracted or inferred from this quote. The expert must be fair and independent. The expert must only opine on areas within their expertise.

In providing guidance as to how an expert’s evidence can carry conviction, Lord Strachan considered what duties the expert owes to the court.

“Their duty is to furnish the Judge or jury with the necessary scientific criteria for testing the accuracy of their conclusions, so as to enable the Judge or jury to form their own independent judgement by the application of these criteria to the facts proved in evidence.”

The court wants to be informed of the facts; the options for analysing those facts; and the expert’s conclusion from analysing the facts. Lord Strachan explicitly states that the “bare ipse dixit of a scientist, however eminent… will normally carry little weight”. Thus, an opinion on its own is insufficient and carries little conviction. Rather the court wants to understand the analysis and thought process of the expert so the court can form its own opinion. As in England, it is therefore important for experts to keep fact and opinion separate and clear.


Experts and those who instruct them should be aware of the rules and guidance of the applicable jurisdiction. In both jurisdictions, experts should be independent, professional and fair and work within the bounds of their expertise. In England, experts must also be aware of their overriding duty to the court and the duties to act expeditiously and proportionately. In both jurisdictions, experts must be prepared to fully explain their methodology and analysis of the facts and how they have arrived at their opinions. Experts in England are required to set out in their report that they have complied with their duties. There is no such requirement in Scotland. Also, experts must accept that ultimately the court has the final say.