How to Prepare Expert Reports for a Commercial Dispute

Expert reports are a central feature of many commercial disputes in the courts and tribunals of England and Wales, especially where technical, financial, economic or specialised knowledge is required to resolve contested issues. These reports present expert opinion evidence that helps judges or arbitrators understand complex subject‑matter outside their own experience. Preparing an expert report that meets legal standards, supports legal arguments, and withstands scrutiny can significantly affect the outcome of a case. This article explains what expert reports are, how to prepare them properly, the legal framework and procedural requirements, and practical steps that lawyers and experts should consider in commercial disputes.

What Is an Expert Report?

An expert report is a written document prepared by a qualified specialist - such as an accountant, engineer, economist, surveyor or technical consultant - that provides the expert's opinion on specific factual issues in a commercial dispute. The expert's role is not to advocate for the instructing party but to assist the court or tribunal by providing independent, objective analysis on matters within their expertise. Under the Civil Procedure Rules (CPR) Part 35 and Practice Direction 35, expert evidence is tightly regulated and subject to standards of independence, relevance, clarity and disclosure.

When Are Expert Reports Needed?

Expert reports are typically needed in commercial disputes where the court or tribunal lacks the specialist knowledge to assess evidence without additional technical or professional input. Common examples include:

• Valuation disputes, including share valuations or business valuations;
• Complex contractual or financial modelling disputes;
• Intellectual property or damage quantification issues;
• Construction defects or technical engineering assessments;
• Market analysis, competition, or economic loss quantification.

Before relying on expert evidence, parties must generally obtain permission from the court for both the expert's report and, if required, that expert to give oral evidence at trial.

The Legal Framework Governing Expert Reports

Civil Procedure Rules (CPR) Part 35

CPR Part 35 sets the statutory requirements for expert evidence in civil proceedings in England and Wales. It requires that:

• Expert evidence is limited to what is reasonably required to resolve the proceedings;
• Experts must be suitably qualified and instructed properly;
• The expert owes a primary duty to the court, not to the instructing party; and
• Expert opinions must be impartial, balanced and robust.

Practice Direction 35

Practice Direction 35 supplements Part 35 by setting out specific content and form requirements for expert reports. According to this direction:

• Reports must be addressed to the court, not to the instructing legal team or party;
• They must contain details of the expert's qualifications and experience;
• They must state the instructions on which the report is based and all material facts considered;
• The expert must clarify which facts are within their own knowledge and which are based on assumptions;
• If there is a range of opinion on an issue, that range and reasons for the expert's view must be summarised;
• Reports must include a summary of conclusions and any qualifications to those opinions; and
• The expert must include a statement confirming their understanding of their duty to the court and compliance with CPR and Practice Direction 35.

The expert's report must also be verified by a statement of truth, confirming the accuracy of the facts and opinions contained within.

Step‑by‑Step Guide to Preparing an Expert Report

1. Clarify the Expert's Instructions

A clear, precise instruction is the foundation of a useful expert report. Instructing solicitors should ensure that:

• The issues requiring expert input are identified and defined;
• The expert understands the precise questions they are being asked to address; and
• The instruction reflects any court directions or timetables relating to expert evidence.

Experts must be instructed early enough to allow sufficient time for analysis and drafting before reporting deadlines.

2. Confirm Expert Qualifications and Independence

At the beginning of the report, experts should outline their:

• Academic qualifications and professional accreditations;
• Relevant experience in the field; and
• Any potential limitations on their expertise.

Experts should also disclose any potential conflicts of interest or connections to the parties, as transparency supports the report's credibility.

3. Set Out Facts and Assumptions Clearly

An expert report should begin with a clear summary of the material facts and instructions on which the expert's opinion is based. It must also:

• Distinguish between facts within the expert's direct knowledge and assumptions based on instructions or data provided;
• Clearly identify any assumptions and explain how they affect the expert's conclusions; and
• List data, documents, test results or other evidence relied upon in forming the opinion.

Experts should make clear if any critical data is missing or if they have insufficient information to give a definitive opinion, explaining the basis for any provisional conclusions.

4. Provide Reasoned, Objective Opinions

Experts must present reasoned explanations for their opinions. Practice Direction 35 expects experts to:

• Explain their methodology and analysis in a clear, logical way;
• Summarise any alternative views or ranges of opinion among experts; and
• Justify why their opinions are reliable and relevant to the dispute.

Reports should be written so that judges and lawyers - who may not share the expert's professional background - can understand the reasoning and conclusions without specialised interpretation.

5. Include Conclusions and Limitations

A good expert report concludes with:

• A summary of key findings;
• Clear, concise conclusions on each question posed in the instruction; and
• Any limitations or qualifications to the opinion, such as recognised uncertainties or unresolved factual gaps.

Experts should avoid unsupported speculation or advocacy; their primary duty is to the court, not to the party instructing them.

6. Finalise With a Statement of Truth

The report must end with a statement of truth in the form prescribed by Practice Direction 35. This confirms that:

• The expert has distinguished between matters of fact and opinion;
• Facts within the expert's knowledge are true;
• The opinions expressed are the expert's true and complete professional opinion; and
• The expert understands their duty to the court.

False or misleading statements can expose the expert to contempt of court proceedings, highlighting the importance of accuracy and integrity.

Practical Considerations and Best Practice

Follow Court Directions Rigorously

Commercial cases are often subject to strict case management timetables that include deadlines for expert reports. Failing to comply can jeopardise the admissibility of evidence or professional credibility.

Keep Reports Focused and Concise

Judges and tribunals favour reports that are limited to issues that are reasonably required to decide the dispute and that avoid unnecessary detail. As noted in the commercial court guides, reports should be as concise as possible without sacrificing completeness.

Key Takeaways

Expert reports play a vital role in commercial disputes when specialised knowledge is needed to resolve contested issues. Preparing a compliant and persuasive expert report involves:

• Understanding the legal requirements under CPR Part 35 and Practice Direction 35;
• Providing clear and well‑reasoned analysis tied to defined instructions;
• Distinguishing between fact and opinion, disclosing qualifications and assumptions;
• Presenting conclusions in accessible language while maintaining technical rigour; and
• Including a verified statement of truth.

High‑quality expert reports help the court or tribunal reach a fair, informed decision and can significantly influence the outcome of commercial litigation.