CrimPR Rule 19 — Expert Witness Duties and Compliance
Part 19 of the Criminal Procedure Rules 2020 governs every expert witness instructed in criminal proceedings in England and Wales. This guide explains the overriding duty to the court, the mandatory report requirements under Rule 19.4, the written declaration of compliance, and the joint expert statement procedure under Rule 19.6.
What Is CrimPR Rule 19?
CrimPR Rule 19 is Part 19 of the Criminal Procedure Rules 2020 (Statutory Instrument 2020/759). It is the primary legal framework governing the use of expert evidence in criminal proceedings in England and Wales, applying to all courts — the Crown Court, magistrates' courts, and the Court of Appeal — without distinction as to the discipline of the expert or the nature of the proceedings.
Before Part 19, expert evidence in criminal proceedings was governed by a patchwork of common law principles and practice directions. The consolidation of these rules into a single statutory instrument created a clear, enforceable framework that applies uniformly to all expert witnesses — whether a consultant psychiatrist instructed on a fitness to plead assessment, a forensic toxicologist addressing a drug driving charge, or a digital forensics expert analysing mobile phone evidence.
The Rules are updated periodically. Solicitors and barristers instructing expert witnesses should always verify that they are working from the current version of Part 19, available from the Ministry of Justice and the Criminal Procedure Rules Committee.
The Six Sub-Rules of Part 19
Select a sub-rule to read the full explanation.
When Part 19 Applies
Part 19 applies in any criminal proceedings where a party wants to introduce expert evidence, or where the court requires expert evidence on a matter that is outside the knowledge and experience of a lay tribunal. The rule applies in the Crown Court, magistrates' courts, and the Court of Appeal. It covers all disciplines of expert evidence — psychiatric, psychological, forensic, medical, toxicological, and digital forensics — without distinction. Where a party intends to rely on expert evidence at trial, they must comply with Part 19 from the point of instruction, not merely at the point of service.
CrimPR Rule 19 Compliance Checklist
Before serving an expert report in criminal proceedings, instructing solicitors should verify that the report satisfies every mandatory requirement under Part 19. A non-compliant report may be challenged at trial, excluded by the court, or returned to the expert for amendment — all of which delay proceedings and increase costs.
The most frequently cited Rule 19.4 non-compliance is the omission of the written declaration under Rule 19.4(i). Without this declaration, the report is technically non-compliant regardless of the quality of the expert opinion it contains. All Expert Witness UK panel experts include the declaration as a standard element of every report.
CrimPR Rule 19 vs CPR Part 35 vs FPR Part 25
The three procedural frameworks governing expert evidence in England and Wales share the same overriding principle — the expert's duty to the court — but differ in their specific requirements. Understanding these differences is important for solicitors who instruct experts across multiple practice areas. An expert who is familiar with CPR Part 35 in civil proceedings will need to adapt their approach when instructed in criminal proceedings under CrimPR Rule 19.
| Aspect | CrimPR Rule 19 | CPR Part 35 | FPR Part 25 |
|---|---|---|---|
| Governing Rules | CrimPR Part 19 (SI 2020/759) | CPR Part 35 | FPR Part 25 |
| Proceedings | Criminal courts (Crown Court, Magistrates') | Civil courts (County Court, High Court) | Family courts (Family Court, Family Division) |
| Overriding Duty | Duty to the court (Rule 19.2) | Duty to the court (Rule 35.3) | Duty to the court (Rule 25.3) |
| Report Declaration | Written declaration required (Rule 19.4(i)) | Statement of truth required (PD 35) | Declaration of truth required (PD 25A) |
| Joint Statements | Rule 19.6 — joint expert meeting | Rule 35.12 — without prejudice meeting | Rule 25.16 — experts' discussion |
| Court Permission | Not always required; court may limit | Permission required (Rule 35.4) | Permission required (Rule 25.4) |
| Single Joint Expert | Rarely used in criminal proceedings | Common in lower-value civil claims | Common in children proceedings |
How to Ensure CrimPR Rule 19 Compliance When Instructing an Expert
Compliance with Part 19 is a joint responsibility. The instructing solicitor must provide a compliant letter of instruction, keep the expert informed of all relevant developments, and review the report before service. The expert must produce a report that satisfies every requirement of Rule 19.4. Expert Witness UK manages this process end to end — from expert selection to report review and court attendance coordination.
Verify the expert's qualifications and specialist register status
Before instructing, confirm that the expert holds the qualifications, specialist register status, and professional body membership relevant to the specific issue. Request a CV and check for medico-legal experience in criminal proceedings. Expert Witness UK provides a CV for every panel expert promptly upon instruction.
Provide a compliant letter of instruction
The letter of instruction must set out the facts of the case, the specific questions the expert is asked to address, the relevant legal framework, and the court timetable. The expert must be told that their overriding duty is to the court. Expert Witness UK's case managers assist with drafting compliant letters of instruction.
Review the report for Rule 19.4 compliance before service
Before serving the report on the prosecution and the court, check that it contains all mandatory elements under Rule 19.4, including the written declaration of compliance. A report that omits the declaration or fails to address the range of opinion is non-compliant and may be challenged.
Manage supplementary questions within the Rules
Supplementary questions to the expert must be proportionate and must be put in writing. The expert's answers form part of the expert evidence and are subject to the same Rule 19 obligations. Questions that seek to influence the expert's opinion rather than clarify it are impermissible.
Facilitate the joint expert meeting if directed by the court
If the court directs a joint expert meeting under Rule 19.6, provide the expert with the opposing report and the agreed agenda. The joint statement must be signed by both experts and served on the court and all parties. Solicitors must not attempt to influence the content of the joint statement.
Related Subtopics
The following concepts are directly related to CrimPR Rule 19 and form part of the compliance framework for expert evidence in criminal proceedings.
The fundamental obligation under Rule 19.2 that an expert's primary duty is to assist the court impartially, overriding any duty to the instructing party.
The mandatory statement required by Rule 19.4(i) in which the expert confirms they understand their duty to the court and have complied with Part 19.
Where there is a body of opinion on a matter, Rule 19.4(f) requires the expert to summarise that range and explain the reasons for their own view within it.
A document produced under Rule 19.6 by experts for the prosecution and defence, identifying areas of agreement and disagreement on the issues they have been asked to address.
The document sent by the instructing solicitor to the expert setting out the facts, the specific questions to be addressed, the relevant legal framework, and the court timetable.
The mandatory section of an expert report under Rule 19.4(a) setting out the expert's academic qualifications, professional registrations, and relevant medico-legal experience.
The obligation under Rule 19.2(6) requiring an expert to notify the instructing party immediately if their opinion changes after the report has been served.
The equivalent framework governing expert witnesses in civil proceedings, with similar overriding duty and report content requirements but different procedural rules.
Frequently Asked Questions — CrimPR Rule 19
These questions reflect the most common queries from solicitors and barristers instructing expert witnesses in criminal proceedings.
Related Guides in This Cluster
CrimPR Rule 19 sits at the centre of the compliance cluster. These pages expand on specific aspects of expert witness duties and procedures.
Instruct a Rule 19 Compliant Expert
Every Expert Witness UK panel expert is trained in CrimPR Rule 19 compliance. CV and fee quote provided promptly.
Instruct an Expert- What Is CrimPR Rule 19?
- The Six Sub-Rules of Part 19
- Compliance Checklist
- CrimPR vs CPR vs FPR
- How to Ensure Compliance
- Related Subtopics
- Frequently Asked Questions
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