Expert Evidence
Plain-English digest of CPS prosecution guidance.
AI-generated summary — not verbatim. This is a plain-English digest, not the official CPS text. It may omit detail or fall out of date. Do not rely on it for a charging decision — read the full guidance on cps.gov.uk and check the current legislation.
This guidance provides a comprehensive overview for prosecutors on the use of expert evidence in criminal proceedings. It covers the definition of an expert witness, the duties and responsibilities of expert witnesses, the admissibility of expert evidence, and the protocols for selecting and instructing experts. Additionally, it emphasizes the importance of ensuring the reliability of expertise and understanding the legal framework surrounding forensic evidence in court.
Key points
- Experts assist in determining issues of guilt or innocence.
- Expert evidence should be objective and unbiased.
- The admissibility of expert evidence depends on its relevance and reliability.
- Prosecutors must ensure the expertise of the witness is relevant to the case.
- Challenges to the integrity of expert evidence can be made during cross-examination.
Public-interest factors
- Ensuring the reliability of forensic science in criminal cases.
- Protecting the integrity of the criminal justice system.
- Upholding the rights of defendants by scrutinizing expert evidence.
- Ensuring justice is served based on sound scientific evidence.
This is a factual digest of guidance published by the Crown Prosecution Service. Digested 2026-07-15. BlueLineHub is independent and not affiliated with the CPS.