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The Role of The Crown Prosecution Service

The Crown Prosecution Service is the government department responsible for prosecuting criminal cases investigated by the police in England and Wales.

As the principal prosecuting authority in England and Wales, we are responsible for:

  • advising the police on cases for possible prosecution
  • reviewing cases submitted by the police
  • determining any charges in more serious or complex cases
  • preparing cases for court
  • presenting cases at court

Find out more about the role of the Crown Prosecution Service

CPS issues prosecutor checklist for current cases involving Low Copy Number DNA analysis


Crown Prosecution Service lawyers have today been provided with the latest information on Low Copy Number DNA testing and guidance on how to deal with cases where it is used. This follows the public statement last week in which, following a review of current cases using LCN, the service stated that none gave cause for concern.

Director of Public Prosecutions, Sir Ken Macdonald QC, said:

"By giving all our lawyers the fullest possible information, we hope to add confidence and clarity to the issues surrounding this technique, although it is only one of a number of forensic tools available to detect criminals and bring them to justice."

Developed in conjunction with the Association of Chief Police Officers (ACPO), the Forensic Science Regulator at the Home Office and the Forensic Science Service, the guidance explaining how the FSS LCN technique works, validation points and strengths and limitations. A checklist consists of a series of questions designed to help police and prosecutors in case preparation where LCN DNA may be used.

The CPS expects to issue further publications explaining similar DNA processes offered by other forensic science providers.

  1. The guidance and prosecutor's checklist are available on this CPS website in the Publications section.

    Low Copy Number DNA analysis (LCN) - Prosecutors' checklist of questions

    Low Copy Number DNA testing in the Criminal Justice System

  2. In the judgment in the Omagh bombing case, R v Hoey, (20 December 2007), the Judge expressed concerns about Low Copy Number (LCN) DNA analysis, conducted by the Forensic Science Service Ltd (FSS), used in evidence. In particular he expressed concerns about the extent to which the scientific validity of the technique had been demonstrated.
  3. LCN is a form of generic Low Template DNA analysis, used when the available crime scene DNA sample is very small, (for example, such as might be obtained from a person's contact with a surface rather than a bloodstain). LCN is the service offered by the FSS, and other low template DNA profiling services are offered by other forensic science providers in the UK.
  4. On 14 January 2008, the CPS published a statement following internal review of current cases involving the FSS use of LCN DNA analysis - Review of the use of Low Copy Number DNA analysis in current cases: CPS statement.
  5. Media enquiries to CPS Press Office on 020 7710 6088.