An expert witness in civil proceedings in England and Wales occupies a distinctive and carefully regulated role. Unlike an ordinary witness of fact, who gives evidence about what they have seen or done, an expert witness is permitted to offer opinion evidence within their field of expertise. This privilege carries with it a set of strict duties, principally governed by Part 35 of the Civil Procedure Rules (‘CPR 35’) and its accompanying Practice Direction. Anyone considering accepting instructions as an expert should understand that these duties are not merely procedural formalities, but fundamental obligations that shape the entirety of their involvement in a case.
The central principle underpinning CPR 35 is that an expert’s overriding duty is to the court. This duty takes precedence over any obligation to the party who instructs or pays them. In practical terms, this means that an expert must provide evidence that is independent, objective, and unbiased. They are not an advocate for the client’s case, nor are they to tailor their opinion to support a particular outcome. Instead, their role is to assist the court in reaching a just and informed decision by offering professional insight that lies outside the ordinary knowledge of the judge.
Before accepting an instruction, a prospective expert should therefore consider whether they can comply fully with this duty of independence. This includes reflecting on any potential conflicts of interest, the limits of their expertise, and whether they have sufficient time and resources to undertake the work properly. Accepting instructions in an area beyond one’s competence, or in circumstances where independence might reasonably be questioned, would be inconsistent with the requirements of CPR 35.
CPR 35 also imposes specific obligations as to the form and content of expert evidence, most notably in the preparation of written reports. An expert’s report must be addressed to the court and must set out, in a clear and transparent manner, the substance of their opinion and the basis upon which it is reached. This includes identifying the material facts and assumptions relied upon, explaining the methodology used, and acknowledging any range of reasonable opinion within the relevant field. Where an issue falls outside the expert’s expertise, this must be stated. Equally, if the expert’s opinion changes at any stage, there is a continuing duty to inform those instructing them without delay so that the court can be notified if necessary.
Another important feature of CPR 35 is the court’s active role in controlling expert evidence. Permission is generally required before expert evidence can be relied upon, and the court may limit the number of experts or direct that a single joint expert be instructed by the parties. Experts may also be required to meet with their opposite number to identify areas of agreement and disagreement, and to produce a joint statement for the court. A prospective expert should be aware that their work will therefore often be subject to scrutiny not only by the parties, but also by other experts and the court itself.
In addition to these formal requirements, CPR 35 expects experts to maintain proper standards of professional conduct throughout their engagement. This includes keeping appropriate records of instructions and communications, ensuring that their reasoning is robust and defensible, and approaching the task with the same level of care and rigour that would be applied in their ordinary professional practice. The role can involve attending court to give oral evidence and to be cross-examined, which requires both preparation and a clear understanding of the issues in dispute.
In summary, acting as an expert witness is a serious professional undertaking governed by well-established rules and expectations. CPR 35 makes clear that the expert’s function is to assist the court impartially, and this duty informs every aspect of the role, from the decision to accept instructions, through the preparation of reports, to the giving of evidence. Anyone contemplating such work should do so with a full appreciation of these responsibilities, and with a willingness to adhere to the high standards required by the court.
All experts within our network are carefully vetted to ensure they meet the highest standards of independence and professionalism. They understand and adhere strictly to their overriding duty to the court.
Our experts are not career consultants, educational theorists or well-intentioned generalists. They are seasoned practitioners with first-hand operational experience at senior levels, offering courts clear, independent, and robust opinion evidence that reflects how the industry actually functions in practice.
Our experts provide:
City Witness Group
90 Jermyn Street
London
SW1Y 6JD
City Witness Group
90 Jermyn Street
London
SW1Y 6JD
