Following my previous articles examining transparency and independence, I wanted to turn to another principle which, in my view, lies at the very heart of expert evidence. Whilst the duties of independence and objectivity are well understood, they can only be fulfilled if the expert is prepared to investigate the evidence properly rather than simply accepting the factual narrative presented by those instructing them.
This is not a new principle. Indeed, it lies at the very foundation of the obligations imposed upon Expert Witnesses by the Civil Procedure Rules, the Civil Justice Council Guidance, the RICS Practice Statement and the principles established by Cresswell J in National Justice Compania Naviera SA v Prudential Assurance Co Ltd (The Ikarian Reefer) [1993] 2 Lloyd’s Rep 68. Yet, despite those well-established authorities, it remains an issue which continues to arise in practice.
Construction disputes are, by their very nature, adversarial. By the time an Expert Witness is instructed, the parties have usually developed firmly held views as to what occurred, why it occurred and who should bear responsibility. Solicitors provide detailed letters of instruction, witness statements, pleadings, schedules and supporting documentation in order to explain their client’s position and identify the issues requiring expert consideration. Such material is, of course, essential, but it is precisely that, an explanation of one party’s case. It is not, without more, evidence upon which an expert can simply rely.
One of the most important disciplines an Expert Witness must therefore develop is the ability to distinguish between instructions, evidence and opinion. Instructions define the issues requiring consideration. The contemporaneous documents, witness evidence and other factual material provide the evidential foundation. The expert’s role is to analyse that evidence independently and express an opinion based upon their own professional expertise. Once those distinct functions become blurred, there is a real risk that the expert ceases to investigate the issues objectively and instead begins to reinforce the narrative advanced by those instructing them.
The danger is seldom deliberate. More often, it arises because the expert becomes immersed in one side’s case over many months, sometimes years. Conferences with solicitors and counsel, repeated reviews of pleadings and witness statements, together with continual exposure to one party’s explanation of events, can gradually create an environment in which assumptions begin to replace investigation. Confirmation bias, a recognised feature of human decision-making, may then encourage the expert to attach greater significance to evidence supporting a provisional conclusion whilst giving less attention to material pointing in another direction.
It is precisely because of that risk that The Ikarian Reefer remains as relevant today as when it was decided over thirty years ago. The expert is required to provide independent assistance to the Court by way of objective and unbiased opinion, to state the facts and assumptions upon which that opinion is based, to consider material capable of detracting from the conclusions reached and to make clear where insufficient information prevents a concluded opinion from being expressed. Those principles are not procedural formalities. They are practical safeguards designed to ensure that expert evidence remains exactly that—independent expert evidence.
The same philosophy is reflected within the RICS Practice Statement, which requires surveyors acting as Expert Witnesses to consider all material facts, including those which may undermine their conclusions, to distinguish clearly between matters of fact and matters of opinion and to ensure that their overriding duty to the Tribunal is never displaced by the interests of those instructing them. Those obligations are not fulfilled merely by reproducing the required declaration at the conclusion of a report. They are demonstrated by the quality of the investigation that precedes it.
In construction disputes, the contemporaneous documents frequently reveal a more nuanced picture than either party’s pleaded case. Programmes evolve, valuations change, meeting minutes record concerns that later disappear from witness statements and emails written at the time often provide a far more reliable account than recollections prepared years after the event. An expert who accepts instructions without rigorously testing them against the contemporaneous evidence risks constructing an opinion upon incomplete or inaccurate foundations. Conversely, an expert who investigates thoroughly may identify weaknesses in their own client’s case long before those weaknesses are exposed by the opposing expert or the Tribunal.
Far from undermining the instructing party, that process often provides the greatest value. Solicitors are not well served by an expert who merely confirms the position already advanced. They are far better served by an expert who identifies evidential weaknesses early, explains where further investigation may be required and assists in refining the issues that genuinely require determination. A robust opinion founded upon careful investigation is almost invariably more valuable than one that simply reinforces a client’s preferred narrative.
There is another aspect of this issue that has increasingly influenced my own thinking through acting not only as an Expert Witness but also as an adjudicator. Many adjudicators determining complex construction disputes have themselves acted as Expert Witnesses, particularly in relation to quantum and delay. They are accustomed to analysing expert reports and assessing the weight that should properly be attached to competing opinions. Although adjudication rarely involves cross-examination, that does not diminish the importance of independent investigation. If anything, it enhances it. Where the written reports represent the principal expert evidence before the adjudicator, the reasoning contained within those reports assumes even greater significance.
In my experience, the reports that carry the greatest persuasive weight are rarely those expressed in the strongest terms or those which seek to answer every issue in favour of the instructing party. Rather, they are the reports that demonstrate a genuine investigation of the available evidence, acknowledge uncertainty where it exists, identify assumptions openly, engage fairly with competing explanations and explain, through logical reasoning, why one conclusion has ultimately been preferred over another. Those qualities inspire confidence because they demonstrate that the opinion has been earned through investigation rather than constructed through advocacy.
Ultimately, the role of an Expert Witness is neither to accept instructions unquestioningly nor to become another member of the litigation team. The expert’s responsibility is to investigate the available evidence, apply their professional expertise to that evidence and express an opinion that remains independent of the interests of those who happen to be paying their fees. That responsibility may occasionally require the expert to challenge assumptions, request further documentation or identify weaknesses in the very case they have been instructed to consider. In my view, that is not a failure to support the client; it is the very reason an independent Expert Witness has been instructed in the first place.
Perhaps, therefore, one of the most important questions an Expert Witness should ask throughout every instruction is not whether they have accepted the instructions they have received, but whether they have properly investigated them. The distinction may appear subtle, but it is fundamental to the credibility of expert evidence and, ultimately, to the confidence that courts, tribunals and adjudicators are entitled to place in those entrusted to assist them.
As always, I welcome respectful discussion from fellow Expert Witnesses, adjudicators, arbitrators, solicitors, barristers and construction professionals. The exchange of professional experience is one of the best ways in which we continue to improve the standards expected of Expert Witnesses.