More than a simple question of quantum? A cautionary guide to expert evidence

17th September 2018

The origins of the quantity surveyor can be traced back in history to the late 17th century during which the restoration of London gathered momentum, following the Great Fire of 1666. Prior to this date, tradespeople were typically paid by the day; but, mindful of the extent of the restoration after the fire, it was decided that each trade would only be paid for the quantity of work completed.

This meant that one had to measure the works, either from drawings or as works progressed, and that payment would be directly commensurate with the quantity completed. This development would directly lead to the evolution of the quantity surveying profession.

Given the rich history of this profession, it is unsurprising that a firm body of expertise has since developed with established principles and rules of conduct. That being so, it is perhaps even less surprising that quantity surveyors and quantity surveying experts play an important role in the resolution of construction disputes. Consequently, the selection and appointment of an independent quantum expert is a well-trodden path for instructing solicitors tasked with resolving disputes.

Against this backdrop, it is therefore quite understandable that when an expert, particularly a quantity surveyor, fails to adequately perform their duties to the court or tribunal, it will cause consternation among their peers.

To the aspiring quantum expert, it is of paramount importance they are technically proficient, which may be demonstrable by the membership of a professional body such as the Royal Institution of Chartered Surveyors (RICS) or from experience in the field. However, often it is not the technical capabilities that draw criticism, but rather the failure of the expert to act in accordance with the principles and duties of an independent witness.


In essence, the rules or guidelines for expert witnesses are laid down in part 35 of the Civil Procedure Rules (CPR); the corresponding practice direction; and the guidance for the instruction of experts in civil claims. The rules are influenced to a significant degree by the seminal statements of Justice Cresswell in the now-familiar Ikarian Reefer case. There, the judge summarised the duty of an expert as “impartial, objective, unbiased and uninfluenced by the pressures of the dispute resolution process or by any party”.

In addition, the RICS publishes its own guidance for members who act as expert witnesses. The document provides helpful assistance, advice and clearly defined standards. Its principal message for the many quantity surveyors acting as experts is a reminder that the primary duty of an expert witness is not to the client, but to the tribunal where the expert report and evidence is given.

In view of the above, it is evident that while an expert assumes a responsibility to its own client to exercise reasonable skill and care, its overriding duty will always be to the court or tribunal. In that respect, the report should always be addressed to the tribunal where the evidence is heard, and not to the party from whom the expert has received instructions.

The role of the expert is to provide independent, objective and unbiased opinion, and to demonstrate that they are assisting the courts in an authentic, ethical and transparent manner.


The CPR does not expressly lay down guidelines in relation to the conduct of the expert, but seemingly this is captured by the principle that the expert is there to provide independent assistance to the court by way of objective and unbiased opinion. Accordingly, there are numerous instances where judges have been highly critical of an expert’s lack of cooperation, personal animosity and failure to give clear unbiased evidence.

An expert who demonstrates that they are doing their best to help the tribunal in a fair, transparent and independent way, and not by demeaning the opponent, is much more likely to be a compelling witness. Of course, the expert is expected to cooperate with the opposing expert as far as possible. An expert who treats cross-examination questions personally, or indicates that there is animosity with the opposing expert, is much less likely to be persuasive to the judge.

There may be situations where the experts are unable to agree and, while this is not unusual, it may give rise to a substantial disparity in their respective opinions. Where this occurs, the court will expect that experts continue to act in a professional and helpful manner.

In practice, it has been pointed out that experts appointed in civil litigation should have no reason to fall out, and if matters of personal disagreement result in failing to comply with the orders of the court, it may have damaging repercussions for the experts and/or the clients.


Expert evidence is normally given in a written report unless the court or tribunal directs otherwise. Coupled with the fact that oral evidence may not always be permitted, a well-presented and coherent expert report is vital to ensure that the opinions formed, and the supporting facts, are easily followed and understood.

On complex cases, the volume of evidence for the court or tribunal to consider may be considerable, and therefore an expert report, which is poorly presented or inadequately referenced, may find that it is granted little weight as evidence. Where appendices are necessary, as they often are, the expert should ensure that the report remains free-standing or self-contained. Failure to adhere to these principles may lead to a report that becomes a presentational nightmare to put before the court in evidence.

Experts should not lose focus on the purpose of the expert report – its intention is to provide comprehensive impartial evidence to assist the court in making their decision.

Additionally, experts must ensure that they do not lose focus on the purpose of the report. All too often, experts are criticised for producing an overly complicated report, which is littered with technical jargon or convoluted calculations. An expert report should assist the court and the counsel relying on it by making complex issues easier to understand. This should be done by collating the relevant material in a comprehensive way that highlights its significance to the non-expert and which is persuasive both to the judge and to the other side.

The guidance from the courts suggests that many expert reports are simply too long, largely because they contain an excessive narrative of the history and the facts, rather than analysis and opinion.

The message here is simple: expert reports should be succinct, focused and analytical, and based on all the evidence available.

Experts should not lose focus on the purpose of the expert report – its intention is to provide comprehensive impartial evidence to assist the court in making their decision.”
John Jones, Executive Director, HKA

The sound quantum expert is undoubtedly one who has acquired, by study and experience, the professional expertise or knowledge needed to be able to take complex issues and provide opinions that are easy to understand. However, it shall also be incumbent upon the expert that they adhere to the duties and responsibilities expected of an independent expert witness. The courts have shown that they are highly adept at detecting when experts stray from this duty. Consequently, an expert who gains a reputation as a “hired-gun” is highly likely to see that career short-lived.