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The Practice Direction for expert evidence sets out the procedural rules that expert witnesses must follow in their reports and during proceedings. In England and Wales, the relevant authorities are Civil Procedure Rules Part 35 and Practice Direction 35, supplemented in immigration proceedings by the Upper Tribunal (Immigration and Asylum Chamber) Practice Direction. Furthermore, comparable rules apply in other UK jurisdictions and equivalent procedural rules in the US, Canada, and EU Member States govern expert evidence in those systems. As a result, every expert witness must be familiar with the practice direction governing their case — failure to comply can result in the report being given little or no weight. This article explains what the UK Practice Direction requires.[1]
See related: expert report contents and how to instruct an expert.
Civil Procedure Rules Part 35
Practice Direction 35
Upper Tribunal Practice Direction (Immigration)
Compliance is mandatory, not optional
The Overriding Duty to the Court
CPR rule 35.3 sets out the central principle: "It is the duty of experts to help the court on matters within their expertise. This duty overrides any obligation to the person from whom experts have received instructions or by whom they are paid." Furthermore, this duty must be explicitly acknowledged in the expert report. As a result, an expert who fails to acknowledge this duty risks having their report disregarded. Therefore, every expert report should contain a clear statement to this effect — typically near the beginning of the document.[2]
"It is the duty of experts to help the court on matters within their expertise. This duty overrides any obligation to the person from whom experts have received instructions or by whom they are paid."Civil Procedure Rule 35.3
Form and Content Requirements (PD 35 §3)
Practice Direction 35 paragraph 3 sets out the formal requirements for expert reports. Key elements include: (1) compliance with relevant professional code of practice; (2) statement of the expert's qualifications; (3) details of any literature or material relied upon; (4) statement of facts and assumptions on which opinions are based; (5) identification of any matters that the expert considers that other experts might disagree with; (6) summary of the conclusions reached; (7) statement that the expert understands their duty to the court and has complied; (8) signed statement of truth. Furthermore, where the expert is not able to give an opinion without qualification, the qualification must be stated. As a result, the report must be self-contained — providing all the information needed to assess its weight.[3]
| PD 35 Para | Requirement | Practical Implication |
|---|---|---|
| §2.2 | Expert duty to the court | Acknowledge in report |
| §3.2(1) | Details of qualifications | CV / qualifications section |
| §3.2(2) | Literature and materials | List sources used |
| §3.2(3) | Facts/assumptions stated | Distinguish fact from opinion |
| §3.2(4) | Distinguish own vs others' knowledge | Cite each fact's source |
| §3.2(5) | Range of opinion | Note where others might disagree |
| §3.2(6) | Summary of conclusions | Provide a clear summary |
| §3.3 | Statement of truth | Sign at the end |
The Statement of Truth
Practice Direction 35 paragraph 3.3 prescribes the exact wording of the statement of truth: "I confirm that I have made clear which facts and matters referred to in this report are within my own knowledge and which are not. Those that are within my own knowledge I confirm to be true. The opinions I have expressed represent my true and complete professional opinions on the matters to which they refer." Furthermore, providing a false statement of truth is a contempt of court. As a result, the statement is not a formality — it is a serious legal undertaking. Therefore, no expert should sign a statement of truth without first verifying every factual claim and opinion in the report.[4]
Upper Tribunal IAC Practice Direction
The Upper Tribunal (Immigration and Asylum Chamber) Practice Direction supplements CPR PD 35 for immigration cases. Key additions include: experts must be familiar with country guidance cases relevant to the country; reports must be current (typically no more than 12 months for active conflict countries); experts must be available for cross-examination if required; reports must address Home Office CPIN and other government country evidence. Furthermore, the Upper Tribunal expects reports to be focused on the issues — not generic country surveys. As a result, immigration-specific expert practice imposes additional requirements beyond general civil practice. Therefore, experts working in asylum cases should familiarise themselves with the UT IAC Practice Direction in addition to general civil rules.[5]
Communicating Changes of Opinion
CPR rule 35.10 and PD 35 §4.3 require an expert who changes their opinion to communicate that change to the parties. Furthermore, where an expert receives new information that affects their opinion, they must reconsider — and if their opinion changes, they must say so. As a result, the duty of independence requires the expert to update opinions as new information emerges. Therefore, experts should not treat their initial report as final — and lawyers should not pressure experts to maintain opinions in the face of new evidence.[6]
Common compliance failures: The most common failures observed at the Upper Tribunal include: (1) failing to acknowledge the duty to the court; (2) failing to state the facts and assumptions on which opinions are based; (3) failing to engage with country guidance; (4) producing generic rather than case-specific reports; (5) not including a signed statement of truth; (6) using outdated sources. As a result, even strong substantive analysis can be undermined by procedural failures. Therefore, a procedural compliance checklist should accompany every expert report.
Cross-Examination and Hearings
Experts may be required to attend hearing for cross-examination. CPR rule 35.5 provides that, where an expert report has been disclosed, the other party may cross-examine. Furthermore, where there is a dispute between experts (e.g., a country expert for the applicant and a Home Office country information note), the tribunal may order a written question-and-answer process (Part 35.6) or oral evidence. As a result, experts should be prepared to defend their methodology and conclusions at hearing. Therefore, the expert should review their report shortly before the hearing and refresh their knowledge of the source materials.[7]
Consequences of Non-Compliance
Non-compliance with the Practice Direction has serious consequences. The Tribunal may: give the report no weight; refuse to admit the report; order the party to remedy the defect at their own cost; in extreme cases, refer the expert to their professional body. Furthermore, where non-compliance reflects bias or advocacy, the expert's standing in future cases may be affected. As a result, the costs of non-compliance fall on both the expert (reputation, future instructions) and the applicant (case undermined). Therefore, procedural compliance is an investment in the case's success — not a bureaucratic exercise.[8]
Conclusion: Procedural Compliance as Foundation
The Practice Direction governing expert witnesses is the procedural foundation on which all substantive expert evidence rests. Furthermore, compliance is not optional — non-compliance can defeat even the most thorough substantive analysis. As a result, every expert preparing a report should work through a compliance checklist before signing. Therefore, both experts and the lawyers instructing them must understand and respect the procedural framework.
Footnotes
- CPR Part 35; Practice Direction 35 (Civil Procedure Rules, England and Wales).
- CPR rule 35.3 (duty to the court).
- Practice Direction 35 §3 (form and content of expert reports).
- Practice Direction 35 §3.3 (statement of truth wording).
- Upper Tribunal IAC Practice Direction on Expert Evidence.
- CPR rule 35.10; Practice Direction 35 §4.3 (changes of opinion).
- CPR rules 35.5 and 35.6 (cross-examination and written questions).
- Consequences of non-compliance; Upper Tribunal decisions on procedural failures.
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