What is... CPR Part 35?

When expert evidence is required in a civil court case in England and Wales, the process must comply with specific legal rules. Chief among these is Part 35 of the Civil Procedure Rules (CPR) - the section that governs the use, duties, and conduct of expert witnesses.

Whether you’re a solicitor instructing an expert, a clinician providing an opinion, or a legal professional reviewing a report, understanding CPR Part 35 is critical for ensuring that expert evidence is both admissible and effective.

This blog offers a guide for solicitors, clinicians, and expert witnesses involved in civil litigation.

What Is CPR Part 35?

CPR Part 35 is the part of the Civil Procedure Rules that regulates the use of expert evidence in civil proceedings. It sets out the rules that must be followed when expert witnesses are instructed to give evidence in court. The overriding purpose of these rules is to ensure that expert evidence is clear, impartial, and helps the court reach a just decision.

CPR Part 35 is supplemented by Practice Direction 35 (PD35), which provides further detail on formatting, procedures, and expectations of experts.

Why Does CPR Part 35 Matter?

Expert evidence can significantly influence the outcome of a case. CPR Part 35 ensures that:

• Experts act independently of the party instructing them

• Reports are consistent, clearly presented, and address key legal tests

• The court, not the instructing solicitor, is the primary audience for any report

• Parties follow fair procedures when exchanging or challenging expert evidence

Non-compliance can result in expert evidence being disregarded or even costs penalties for the instructing party.

Key Provisions of CPR Part 35

1. Duty to the Court

Under CPR 35.3, an expert witness has an overriding duty to the court. This duty overrides any obligation to the person instructing or paying the expert. The expert must remain independent, objective, and unbiased.

2. Permission to Rely on Expert Evidence

According to CPR 35.4, a party must obtain the court’s permission before relying on expert evidence. The court will consider whether expert input is necessary for the just resolution of the case.

3. Expert Reports

Reports must be comprehensive, clear, and CPR-compliant. They should:

• Be addressed to the court

• Include details of the expert’s qualifications

• Set out the facts and assumptions made

• Explain the reasoning behind the opinion

• Include a formal Statement of Truth and Declaration of Duty

The format is often guided by PD35 and must be appropriate for civil litigation.

4. Joint Experts and Single Joint Experts

The court may direct that a single joint expert (SJE) be appointed where appropriate, especially in lower-value claims. This expert is instructed by both parties jointly to reduce costs and avoid duplication. In more complex claims, each party may be permitted to instruct their own expert, subject to the court’s approval.

5. Questions to Experts

Under CPR 35.6, once expert reports are exchanged, each party may put written questions to the other side’s expert. These must be proportionate and relevant, and must be asked within 28 days of service unless otherwise agreed.

6. Expert Discussions and Joint Statements

The court can order that experts of the same discipline discuss the case and produce a joint statement outlining areas of agreement and disagreement. This often follows Case Management Conferences (CMCs) and precedes trial.

Practice Direction 35 (PD35): Additional Guidance

PD35 complements CPR Part 35 and includes more specific requirements, such as:

• Formatting expectations

• What must be included in the expert’s Statement of Truth

• Limits on the scope of instructions

• What the court expects from a competent, helpful report

Experts and solicitors should be familiar with both the Rule and the Practice Direction to ensure compliance.

CPR Part 35 in the Medico-Legal Context

At Apex Experts, we work with clinicians and legal professionals to produce reports that meet the exacting standards of CPR Part 35. This includes:

• Screening reports and Letters of Advice that support early case strategy (not disclosable)

• Full CPR-compliant medico-legal reports for breach, causation, or condition and prognosis

• Support for Joint Expert Meetings and expert collaboration

• Consistent formatting and content aligned with PD35 and case law developments

Final Thoughts

CPR Part 35 ensures that expert evidence in civil claims is reliable, impartial, and legally robust. Whether you’re preparing a clinical negligence case, quantifying a personal injury, or managing a multi-expert claim, understanding Part 35 is essential for strategic case management.

Failing to comply can damage a claim. Getting it right strengthens your position.