Searchline. Let us do the hunting whatever expert you need. Please call our free SearchLine today on 0161 834 0017

News Detail back to listing

Instructing an Expert
  • Jan 22, 2020
  • Latest News

Whether the expert is instructed before or after charge it is desirable for the decision to instruct an expert to be agreed between the investigator(s) and the prosecution. The advantage of this approach is that:

  • The most appropriate expert can be identified from the outset, i.e. as close to the start of the investigation as practicable in any given case; and
  • The prosecutor can ensure that there is clarity as to what the expert is being asked to provide an opinion on. This is particularly important in cases which involve complex legal issues, for example causation.

This approach should reduce the potential for misunderstanding and delay caused by unnecessary work being undertaken by experts who have been provided with inaccurate or inadequate instructions.

Irrespective of whether an expert witness is instructed by the police or the CPS, the expert will be expected to have regard to the CPS Guidance for Experts Evidence, Case Management and Unused Material and prosecutors should be familiar with its content.

The CPS Guidance for Experts provides a practical guide to preparing expert evidence and disclosure obligations. Unless the information in the booklet is to be incorporated into the letter of instruction to the expert, or the information has already been provided to the expert by the police, the Guidance should be forwarded to the expert along with the Experts self-certificate.

The investigator or prosecutor should ask the expert to complete this in all cases to provide assurance that the expert understands his obligations to the court and his obligations as to disclosure.

If the expert is instructed by the prosecutor, then the prosecutor should clearly identify the work to be undertaken in the terms of reference. This will involve explaining the background to the work and specifying the issues, including a clear exposition of all relevant legal elements, on which an opinion is sought. In some cases, it may be necessary to limit the information given to the expert to avoid the risk of their conclusions being affected by confirmation bias, whereby the expert tests their hypothesis and conclusions by reference to confirming evidence, such as the prosecution's belief at to the identity of the suspect, as opposed to considering potentially conflicting evidence.

Drafting Terms of Reference

When drafting the terms of reference the prosecutor should not assume that the expert has a thorough knowledge of the criminal law and procedure. The law should be explained as succinctly and clearly as possible.

The Terms of Reference should include the following:

  • The extent of the expert's remit i.e. precisely the issues, and/or the suspects, we want the expert to focus upon;
  • The standard to which the expert is being asked to apply. For example, if being asked to address causation, the expert needs to be given clear guidance on the level of certainty the criminal court requires, and the need to avoid 'percentage' conclusions;
  • Where the existing evidence of fact contains disagreement or ambiguity, the Terms of Reference should include an overarching narrative which sets out how the prosecution would propose to put the case in that regard, and ask the expert to provide his assessment based on that narrative. Alternatively, depending on the circumstances, the expert could be asked to advise based on a number of different scenarios. The key point is to ensure that the expert sets out clearly the factual basis upon which the opinion is based;
  • If the material being sent to the expert contains reports from another professional then, insofar as the expert might wish to clarify any issue in the other professional's report, any discussion should be arranged through the investigator. Any discussion should be documented to ensure an auditable trail for disclosure purposes;
  • The expert should be instructed to indicate immediately:
    • If he requires anything further - whether by way of legal guidance, evidence of fact, or expert evidence from other specialists - before reporting back. This should limit the number of experts' reports which are couched in contingent terms;
    • If any part of the Terms of Reference is unclear;
  • An early, informal indication of the report's likely conclusions. This will enable the investigator to liaise with the prosecutor to consider which other areas of evidence- gathering should be undertaken and inform of the overall timetable;
  • All the relevant statements and exhibits. An expert's report based on a limited reading of the evidence is likely to be challenged by the Defence in cross examination;
  • Finally, in terms of the content of the report itself, the expert should be reminded to preface his detailed observations by setting out (1) his experience and qualifications, and (2) an itemised list of the evidence and any other material (including the CPS Guidance for Experts with which s/he will have been supplied; and
  • Timescales for completion of the report. This is vital given the Criminal Procedure Rules.

The Terms of Reference should be scheduled by the disclosure officer and disclosed to the Defence.


Letter of Instruction

A letter template is provided (Annex A below) for use only in cases where the CPS is responsible for instructing the expert. Where the police are responsible for doing so, prosecutors should still assist the police in drafting terms of reference for the expert. The prosecutor should complete the 'Assignment' section, and include the terms of reference. The section on fees may be completed by Operational Delivery staff. .

The Letter of Instruction will need to address the issue of fees.

The expert should be encouraged to sign up to secure email as an efficient way of communicating. Further information and details are available using the link