How Expert Evidence Is Used in Public Liability Claims

Public liability claims often involve disputes over how and why an accident occurred and what caused the claimant's injury or loss. In many cases the facts alone - for example, testimony from witnesses or physical evidence - are insufficient for a judge to make fully informed decisions. That is where expert evidence plays a vital role. This article explains how expert evidence is used in public liability claims in England and Wales, the legal framework governing experts, how reports are prepared and admitted, practical steps for parties, and common questions about expert witnesses.

What Is Expert Evidence?

Expert evidence is opinion evidence provided by an individual with specialist knowledge, education, training or experience in a relevant field that is outside the ordinary understanding of judges and civil courts. Unlike factual witnesses, experts do not testify about what they personally observed; they give opinion‑based analysis to help the court understand complex issues such as whether a surface was defective, how an injury occurred, or whether a standard of care was breached.

For example, in a public liability claim arising from a slip in a supermarket car park, the claimant's solicitor might instruct:

• A chartered surveyor to assess whether a surface was negligently maintained.
• A medical expert to explain the nature and likely cause of injuries.
• An accident reconstruction specialist to analyse how the hazard and injury occurred.
  These expert opinions aim to assist the court to decide questions that lie outside normal judicial experience.

Legal Framework Governing Expert Evidence

Civil Procedure Rules (CPR Part 35)

In civil cases, including public liability claims, the Civil Procedure Rules (CPR Part 35) and Practice Direction 35 set out how expert evidence must be handled. Expert evidence is not automatically admissible; the court's permission is required before an expert can be relied upon. Permission is granted only where the evidence is reasonably required to resolve the issues in dispute.

Key points of CPR Part 35 include:

• An expert's overriding duty is to the court, not to the party instructing them, and they must provide objective, unbiased opinion.
• Experts must have relevant qualifications and experience to support their opinions on the matters in question.
• Permission must be obtained before calling an expert witness or relying on their report.
• Experts often prepare written reports in accordance with CPR requirements; oral evidence at trial may follow if the court approves.

When Expert Evidence Is Needed

Expert evidence is appropriate where a public liability claim involves technical, medical, engineering or scientific questions that a judge cannot fairly assess without specialist insight. Typical scenarios in public liability claims include:

• Analysis of whether a premises owner met health and safety standards.
• Determining whether an injury was caused by the hazard alleged.
• Estimating future medical care needs or loss of earnings in serious injury claims.

If the issues in dispute are straightforward and can be resolved from factual evidence alone, a court may decide expert evidence is unnecessary.

How Expert Evidence Is Prepared

Instruction and Report

The party seeking expert evidence must instruct the expert with clear terms of reference, identifying the issues to be addressed. Reports must typically include:

• The expert's qualifications and experience.
• Facts or assumptions relied upon.
• A reasoned opinion on the matters identified.
• A statement of truth confirming that the expert understands and has complied with their duty to the court.

The expert's opinions must be supported by clear reasoning and, where relevant, recognised methodology. They should make clear what is based on the expert's own expertise and what is an assumption provided by the legal team.

Joint Experts and Expert Meetings

Where appropriate, the court may encourage or order parties to instruct a single joint expert. This can reduce costs and narrow disagreements by ensuring both sides rely on the same technical assessment. Experts may also be directed to meet and prepare a joint statement setting out points of agreement and disagreement. This helps focus the issues for trial and may assist in settlement discussions.

Admissibility and Court's Role

Even with permission, the court assesses whether expert evidence will genuinely assist in determining the case. The evidence must be reliable, relevant and proportionate to the value and complexity of the claim. Courts will refuse to admit evidence that falls outside recognised expertise, lacks sufficient foundation, or is unnecessary for resolving the issues.

Expert Evidence at Trial

Once admitted, expert evidence may be presented in several forms:

• Written reports, exchanged between parties and filed with the court.
• Oral testimony, where the expert is questioned by legal teams and the judge.
• Joint statements summarising areas of consensus and difference.

Because experts must adhere to their duty to the court, they are required to answer questions on their reports objectively and without favour to the instructing party. A party may challenge the opposing expert's evidence by cross‑examination or by instructing an independent expert to respond.

Practical Role of Expert Evidence in Public Liability Claims

Establishing Liability

Expert evidence is often critical to proving that a defendant breached a duty of care. For example, a civil engineering expert might conclude that a floor surface was defective and posed an unreasonable risk to visitors, helping establish negligence. Medical experts can link injuries directly to the incident, distinguishing pre‑existing conditions from those caused by the accident.

Quantifying Loss

Medical and vocational experts can help quantify future care needs, rehabilitation prospects, and loss of earnings for serious injuries. This assists courts or negotiating parties in calculating compensation that reflects long‑term impact.

Informing Settlement

Strong expert reports can influence settlement negotiations. Defendants and insurers may be more willing to offer reasonable settlements when expert opinion clearly supports the claimant's case and quantifies loss with professional credibility.

Risks and Limitations

Expert evidence adds cost and complexity to public liability claims. Courts guard against unnecessary or disproportionate use of experts, particularly in lower-value cases. Permission may be refused or limited if the court deems expert evidence unnecessary to resolve the dispute.

Additionally, experts must maintain independence; evidence that appears biased or lacks clear methodology risks being discounted or excluded. The legal community has highlighted concerns about expert witness quality and regulation, but current rules emphasise the expert's duty to assist the court impartially.

Common Questions About Expert Evidence

Who pays for expert evidence?
Typically, the party who instructs the expert pays fees, although courts may order costs to be shared or awarded to the successful party.

Can both sides use experts?
Yes. Each party may seek permission to call their own experts, or the court may order a joint expert to be used.

Is expert evidence always needed?
Not always. If the issues can be resolved through factual evidence alone, expert evidence may be unnecessary.

What happens if an expert is found biased?
The court can reduce the weight of the evidence, exclude it, or make costs orders against the instructing party if rules are breached.

Key Takeaways

Expert evidence in public liability claims is a specialised form of opinion evidence used to assist courts with complex medical, technical and scientific issues. Governed by CPR Part 35 and Practice Direction 35, experts must act independently and provide objective, relevant analysis to help resolve disputes over liability and loss. Expert reports and testimony can be pivotal in establishing negligence, demonstrating causation, and quantifying compensation. Courts carefully control the admissibility and scope of expert evidence to ensure fairness, efficiency and proportionality.