Few principles underpin the administration of justice more fundamentally than the independence of the Expert Witness. It is a concept that permeates the Civil Procedure Rules, the Civil Justice Council Guidance for the Instruction of Experts in Civil Claims and the RICS Practice Statement and Guidance Note Surveyors Acting as Expert Witnesses. Perhaps most famously, it was articulated by Cresswell J in National Justice Compania Naviera SA v Prudential Assurance Co Ltd (The Ikarian Reefer) [1993] 2 Lloyd’s Rep 68, a case that continues to shape the obligations of Expert Witnesses more than three decades later.
The principles themselves are neither controversial nor unfamiliar. An Expert Witness owes an overriding duty to the Court or Tribunal. That duty overrides any obligation owed to the party instructing or paying the expert. The expert’s role is not to advance a client’s case, but to provide objective, independent and unbiased opinion evidence within the confines of their expertise.
Most experienced experts could recite those principles without hesitation.
The more interesting question, however, is whether independence is something that can simply be declared at the conclusion of an expert report, or whether it is something that must be demonstrated throughout every stage of the instruction.
In my view, it is unquestionably the latter.
One of the greatest risks facing any Expert Witness is not deliberate partiality but unconscious bias. Independence is rarely abandoned overnight. More commonly, it is gradually eroded as an instruction develops and the expert becomes increasingly immersed in one party’s narrative.
The process often begins entirely appropriately. Experts are instructed at an early stage to advise upon technical issues, identify evidential gaps, review witness statements, analyse contractual documentation, comment upon pleadings and assist solicitors and counsel in understanding complex construction and commercial matters. The Civil Justice Council expressly recognises that experts may properly undertake these activities and, indeed, early expert involvement frequently assists in narrowing issues and, in some instances, facilitating settlement before proceedings become entrenched.
Yet the very proximity that enables an expert to add value also presents a subtle professional risk.
Over many months, sometimes years, an expert inevitably becomes familiar with one party’s version of events. Conferences with solicitors, discussions with counsel and continual exposure to one side’s factual narrative may, entirely unconsciously, begin to influence the expert’s thinking. Confirmation bias is not misconduct. It is a recognised feature of human decision-making. Once an individual begins to form a provisional conclusion, there is a natural tendency to place greater weight upon material supporting that conclusion whilst paying less attention to evidence pointing in another direction.
Experts are no more immune to that tendency than anyone else.
It is for precisely this reason that the principles identified in The Ikarian Reefer remain so important. They require experts not only to provide independent assistance to the Court but also to state the facts and assumptions upon which their opinions are based, to consider material that may detract from their conclusions, to identify where issues fall outside their expertise and to make clear where insufficient information prevents a concluded opinion from being reached.
Those principles are reinforced by the RICS Practice Statement, which requires surveyors acting as Expert Witnesses to maintain independence throughout the instruction, to consider material that supports and undermines their conclusions alike, and to ensure that their overriding duty to the Tribunal is never displaced by their relationship with those instructing them.
These obligations should not be viewed as procedural formalities or standard wording to be reproduced towards the end of a report. They are disciplines designed to protect both the integrity of the expert’s opinion and the integrity of the judicial process itself.
One of the clearest hallmarks of genuine independence is an expert’s willingness to identify weaknesses in the case of the party instructing them. Solicitors do not instruct experts merely to validate an existing position. They instruct them because they require an objective professional opinion. Sometimes that opinion strengthens the case. Sometimes it narrows the issues. Occasionally it reveals significant difficulties that had not previously been recognised. All three outcomes represent the expert performing their role properly.
The distinction between an advocate and an Expert Witness therefore becomes critical. An advocate exists to persuade. An Expert Witness exists to assist. An advocate advances the strongest possible case on behalf of a client. An expert follows the evidence wherever it leads, regardless of whether the resulting opinion assists or undermines the case of the party providing the instructions.
That distinction is easy to describe but considerably harder to maintain in practice.
There is, however, another perspective that is perhaps discussed less frequently, namely the role of expert evidence within adjudication.
Unlike litigation, experts involved in adjudication will rarely be subject to cross-examination. Their evidence is almost invariably presented through written reports produced within demanding timescales. It might therefore be tempting to assume that, because the expert will not be tested orally, the consequences of adopting a more partisan approach are somehow reduced.
In my view, that assumption is misplaced.
Many adjudicators appointed to determine complex construction disputes are themselves experienced Expert Witnesses or have previously acted in that capacity, particularly in relation to quantum and delay disputes. They have read hundreds of expert reports and understand the characteristics of evidence that genuinely assists the decision-maker. Equally, they are often quick to recognise reports that resemble submissions rather than independent expert opinion.
The absence of cross-examination does not make a partisan report more persuasive. Indeed, it may have the opposite effect. Where an adjudicator is required to assess competing expert opinions solely on the written material, careful reasoning, balanced analysis and intellectual honesty often become even more important. Reports that fail to engage with adverse evidence, overlook obvious alternative explanations or simply dismiss competing opinions without proper analysis may ultimately carry less weight than reports that demonstrate objectivity and measured professional judgement.
Having acted both as an Expert Witness and as an adjudicator, I have often reflected that the reports carrying the greatest persuasive force are seldom those written in the strongest language or those most closely aligned with a party’s submissions. They are the reports that demonstrate balance, acknowledge uncertainty where it exists, confront inconvenient evidence rather than avoiding it and explain, transparently, why one conclusion has been preferred over another.
Ultimately, whether the decision-maker is a judge, an arbitrator or an adjudicator, the same question arises.
Can confidence be placed in the expert’s reasoning?
That confidence is not earned because the report contains the declaration required by CPR Part 35, nor because it reproduces the wording found within the RICS Practice Statement. It is earned because every page of the report demonstrates independence, objectivity and a willingness to follow the evidence wherever it leads.
Perhaps, therefore, the most revealing question an Expert Witness can ask before signing a report is not whether the required declaration has been included, but whether precisely the same opinion would have been expressed had the expert been instructed by the opposing party and provided with exactly the same body of evidence.
If the honest answer is yes, the expert has probably fulfilled the principles established in The Ikarian Reefer.
If the answer is no, then it may be time to ask whether the line between independent expert evidence and advocacy has become blurred.
I would be interested to hear the views of fellow Expert Witnesses, adjudicators, solicitors, barristers and claims professionals.
Has maintaining true independence become more challenging as experts become involved earlier and more deeply within the litigation process, or do the existing safeguards continue to provide the necessary protection?