In many cases, the value of expert evidence depends on how closely the expert's knowledge and experience match the specific question that needs to be answered. The expert must also understand their duties to the court, work within the limits of their expertise, and provide an independent opinion.

For solicitors, therefore, selecting an expert witness involves more than reviewing a CV. It means considering the nature of the evidence required, the expert's particular experience, professional standing, availability, and whether they meet the case's procedural requirements.

What is an Expert Witness?

An expert witness is a person who provides the court with an opinion on a matter requiring specialist knowledge, skill or experience.

That might involve medical evidence, psychiatry, digital forensics, financial matters, engineering, psychology, toxicology, accident reconstruction or another specialist discipline.

The role is different from that of a factual witness. An expert is not simply describing something they have personally seen or experienced. They use their professional knowledge to assist the court in understanding or determining an issue within their expertise.

The expert's overriding duty is to the court.

Under CPR 35.3, an expert's duty to help the court on matters within their expertise takes precedence over any obligation to the person who instructed or is paying them. Expert evidence should also be restricted to what is reasonably required to resolve the proceedings.

The same principle applies in family proceedings. Practice Direction 25B requires an expert to provide an opinion that is independent of the party or parties instructing them and to confine that opinion to matters within their expertise.

That independence is one of the most important principles to understand when selecting an expert.

One of the easiest ways to make the search for an expert more difficult is to start by looking for a professional before defining exactly what evidence is required.

What does the court need specialist evidence to establish or understand?

Consider a medical case. Searching for a "medical expert" is unlikely to be sufficiently precise. The relevant issue might require expertise in paediatric radiology, neurology, emergency medicine, orthopaedics, psychiatry or another specific discipline.

A case involving digital evidence may require expertise in mobile phone forensics, cybersecurity, data recovery or another particular aspect of digital investigation.

A family case may involve questions relating to mental health, neurodevelopment, attachment, substance misuse or another specialist area.

The more precisely the issue is defined, the easier it becomes to identify an expert whose experience genuinely matches it.

Check Professional Status and Regulation

Professional regulation is another important consideration when selecting an expert witness.

Depending on the discipline, this may involve checking registration with the relevant regulator, membership of a professional body, qualifications, professional history and any other information relevant to their standing.

The position is particularly important in family proceedings.

Changes to the Family Procedure Rules that came into force on 20 July 2026 introduced the concept of a "regulated expert" and, in certain children proceedings, require expert evidence to be provided by a regulated expert subject to specified exceptions. The associated changes to Practice Direction 25B and 25C also require parties to address whether an expert is a regulated expert and, where an exception is relied upon, why a regulated expert is not available.

This is a good example of why expert selection cannot be separated from the case's procedural context. The requirements applying to an expert may depend on the type of proceedings, the issue being considered and the court's directions.

Independent Experts

A solicitor instructs an expert, but the expert is not there to act as an advocate for the instructing party. The expert's opinion must be independent.

The Civil Procedure Rules state that an expert's duty to the court overrides any obligation to the person from whom they have received instructions or by whom they are paid. The Civil Procedure Rules also require expert evidence to be the independent product of the expert and uninfluenced by the pressures of litigation.

This means an expert should be willing to identify evidence that does not support the position of the party who instructed them.

It also means an expert should be prepared to say when:

• an issue falls outside their expertise
• there is insufficient information to reach a reliable conclusion
• their opinion is qualified
• there is a range of reasonable professional opinion or
• further evidence is needed before a conclusion can properly be reached

Consider Conflicts of Interest

An expert may have previously worked with another party, organisation or professional involved in the proceedings. They may also have existing professional, financial or personal relationships that could raise questions about their independence.

A potential conflict does not necessarily mean an expert cannot act, but it should be identified and considered before an instruction is made. The earlier this is established, the less likely it is to create difficulties later in the proceedings.

It is also worth considering whether the expert has previously provided evidence in related proceedings and whether there are any existing relationships with the parties or professionals involved.

The Instruction as Part of the Process

In civil proceedings, CPR 35.10 requires an expert's report to state the substance of the material instructions on which the report was based. Practice Direction 35 also sets out requirements concerning the expert's qualifications, the material relied upon, the facts and instructions relevant to their opinion and the conclusions reached.

A clear instruction therefore benefits both the solicitor and the expert.

It helps the expert understand the precise question they are being asked to address and helps the solicitor ensure that the resulting report deals with the issues that actually matter to the case.

There can sometimes be a tendency to think that more expert evidence will necessarily strengthen a case. The procedural rules take a more proportionate approach.

Under CPR 35.1, expert evidence should be restricted to what is reasonably required to resolve the proceedings. The court can also restrict expert evidence and, in appropriate circumstances, direct that evidence on a particular issue should come from a single joint expert.

Some cases involve questions that sit within highly specialised areas of professional knowledge.

Examples can include:

• paediatric radiology
• neurology
• psychiatry
• IT and digital forensics
• facial mapping
• toxicology
• DNA analysis
• handwriting analysis
• firearms and weaponry
• country-of-origin expertise
• specialist medical disciplines
• engineering and construction
• financial expertise
• other technical or professional fields

Finding the Right Expert

There is no single characteristic that makes someone the right expert witness for every case.

A highly experienced professional may not have the particular expertise required. A specialist may have the right knowledge but not the availability to meet the timetable. An expert may be appropriately qualified but have a potential conflict that needs to be considered.

The expert should have specific expertise relevant to the question the court needs help with.

That distinction is particularly important as cases increasingly involve specialist medical, technological, forensic and professional evidence.

Need help choosing the right expert? Speak to our team today.