Acting as an expert witness: dos and don'ts for veterinary surgeons

A solicitor sends you a bundle of clinical records and asks whether another veterinary surgeon fell below an acceptable standard of care. It may feel like a natural extension of clinical practice, but expert witness work is a distinct legal role with its own rules, risks and responsibilities. Done well, it allows veterinary surgeons to assist in the fair resolution of disputes. Done badly, it can damage a case, your credibility and, potentially, your professional standing.

What is an expert witness?

An expert witness is instructed to give or prepare evidence for court proceedings on matters within their professional expertise. This is different from being a factual witness. A factual witness gives evidence about what they personally saw, did or heard. Factual witnesses should not offer opinions. An expert witness is permitted to offer opinion evidence: to interpret records, explain technical issues and assist the court on matters outside ordinary lay knowledge.

For vets, the distinction matters. If you treated the animal, you may be asked to be involved in a court case but will usually be a factual witness rather than an independent expert. You may be asked to explain your own clinical reasoning, but that is not the same as being instructed to review another practitioner's conduct as an independent expert.

The overriding duty to the court

The most important principle is simple: your primary duty is to the court, not to the party who instructs or pays you. The court rules provide that experts must help the court on matters within their expertise, and that this duty overrides any obligation to the person who is instructing and paying the expert. Your opinion must therefore be your honest, independent assessment, whether or not it helps the party who engaged you.

The Civil Procedure Rules – Part 35 and Practice Direction 35

In civil proceedings in England and Wales, expert evidence is governed principally by CPR Part 35 and Practice Direction 35. The rules are designed to keep expert evidence focused, independent and proportionate. In practical terms, they mean the following.

• Expert evidence is limited to what is reasonably required, and the court controls whether it may be used
• Experts must be independent, objective and unbiased, and must not act as advocates
• Experts must consider all material facts, including those which undermine their view
• If an issue is outside your expertise, or you cannot reach a firm view because the information is incomplete, you must say so
• The report must include the required declaration and statement of truth, and must state the substance of all material instructions
• If your opinion changes after reporting, that change must be communicated without delay.

Professional obligations under RCVS guidance

Veterinary surgeons must also have regard to the RCVS Code of Professional Conduct and supporting guidance. The professional themes are familiar: integrity, competence, independence, impartiality, confidentiality and accountability. A vet who knowingly gives a misleading opinion, or strays beyond genuine expertise, risks criticism not only from the court but also from the regulator.

Practical dos and don'ts

Before accepting instructions, check the role, scope, timetable and likely commitment. Expert work may involve more than writing a report. You may need to answer written questions, attend a conference, discuss issues with the opposing expert, help prepare a joint statement or give evidence at trial.

• Do stay within your genuine expertise. Courts expect precision: an equine orthopaedic specialist should not offer expert opinions on small-animal oncology
• Do remain objective. Consider all the evidence, including material that undermines the position of the party who instructed you. If the facts do not support a criticism, say so
• Do remember the difference between an advocate and an expert. An advocate argues a case. An expert informs the court
• Do keep clear records of instructions, conversations, documents reviewed and reasoning. Good records protect your independence if it is later challenged
• Do say if you cannot reach a definite conclusion. An honest "I don't know" is more credible than an overreaching opinion
• Do tell the parties promptly if your opinion changes after you have reported
• Don't accept instructions where you have a conflict of interest. Disclose any prior involvement with the animal, owner, practice, insurer, breeder, yard, rescue centre, product supplier, colleague or other person connected with the dispute. If in doubt, disclose early
• Don't let the solicitor dictate your opinion. They may ask you to clarify language or consider additional material, but the opinion must remain yours
• Don't discuss the case or your opinions with anyone outside the proceedings unless directed by the court.

Conclusion

Expert witness work can be rewarding, but it demands discipline and independence. Your duty is to the court, your opinion must be your own and you must not stray beyond what you truly know. Get those fundamentals right, and the rest will follow.

This article provides general guidance on expert evidence in civil proceedings in England and Wales. It is not a substitute for legal advice on any particular case.