CPD Part 35
Definition
Part 35 of the English Civil Procedure Rules governing expert witnesses. Requires a written declaration of duty, disclosure of instructions, and a statement of opinion. Parallel provisions for criminal proceedings appear in the Criminal Procedure Rules Part 19.
- Jurisdiction
- England and Wales, civil proceedings
- Governs
- Expert witnesses in civil cases
- Requires
- Written declaration of duty, disclosure of instructions, statement of opinion
- Criminal parallel
- Criminal Procedure Rules Part 19
Common questions
What does the Part 35 declaration of duty actually require an expert to affirm?+
The expert must state in writing that they understand their overriding duty is to help the court on matters within their expertise, and that this duty overrides any obligation to the party instructing and paying them, a formal acknowledgement designed to counter the risk of partisan expert testimony.
Why does Part 35 require disclosure of the instructions given to the expert?+
Disclosing the instructions lets the court and the opposing party see what facts, assumptions, or questions the expert was asked to consider, so they can assess whether the expert's opinion was shaped by selective or leading instructions rather than an independent, complete review of the evidence.
Related terms
- Daubert Standard
- The US federal evidentiary standard (Daubert v. Merrell Dow Pharmaceuticals, 1993) requiring that expert testimony be based on scientifically valid methods with...
- Duty to the Court
- The obligation of expert witnesses in UK proceedings (and, to varying degrees, in other jurisdictions) to assist the court with objective, unbiased...
- Forensic Science Regulator
- A statutory office in England and Wales, given formal powers by the Forensic Science Regulator Act 2021, to set and enforce quality...
- Frye Standard
- The US legal test for admissibility of scientific evidence, originating from Frye v. United States (1923), which required that a technique be...
- Ikarian Reefer Principles
- A set of guidelines from the English civil case National Justice Compania Naviera v. Prudential Assurance (1993), widely cited in English courts,...