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Pre-Trial Witness Interviews - Guidance for Prosecutors

Legal Guidance


This guidance has been prepared for prosecutors undertaking pre-trial witness interviews.

It should be read in conjunction with the Code of Practice signed by the Director in February 2008 which can be accessed here. This guidance is subordinate to the Code of Practice.

Eligibility criteria

A PTWI may be conducted by a Crown Prosecutor designated by the Chief Crown Prosecutor (CCP) for their Area, Deputy Chief Crown Prosecutor (DCCP) or Head of Division (HoD) to conduct such interviews, or by an independent advocate on the authority of a designated Crown Prosecutor.

CPS Prosecutors

To be eligible to conduct PTWIs, prosecutors should have completed the CPS training course on pre-trial witness interviewing. In exceptional cases and with the approval of the CCP, DCCP or HoD, a pre-trial witness interview may be conducted by a prosecutor who has not completed the training.

CCPs/DCCPs/HoDs should formally designate named prosecutors as authorised to conduct PTWIs. A copy of the designation, signed by the CCP/DCCP/HoD, should be retained on file in the Area/Central Casework Division. The designated prosecutors should also be informed by the CCP/DCCP/HoD via e-mail that they have been designated.

Selection of Cases

Interviews may take place in any case in which the prosecutor considers an interview would assist in assessing the reliability of the witness's evidence and/or to assist in understanding complex evidence. The purpose is to enable the prosecutor to reach a better informed decision about any aspect of the case.

Interviews will normally be of most value in serious indictable-only cases. However, nothing precludes the holding of an interview in either-way or summary only cases. The decision to hold such an interview will be a matter for the appropriate team leader/DCP.

The interview may take place at any stage in the proceedings (including pre-charge) until the witness starts to give evidence. Ideally a PTWI will take place before the prosecution decision is made, that is to say pre-charge, or in the case of a threshold test case, as soon as practicable. However, a PTWI should not take place until the police investigation is complete and the witness must have made a witness statement.

The referral process

While some cases suitable for a PTWI will be identified by a PTWI designated prosecutor from his/her own caseload, the majority will be referrals from other prosecutors or even - at a later stage - counsel.

The referral process is set out in the case file form which can be accessed here.

The reviewing prosecutor should consider whether a PTWI would assist in reaching a prosecution decision. If he/she considers that it would, he/she should, at this point, refer the case to the appropriate team leader/DCP for a decision to be made. If the case is pre-charge and suitable for police bail, the police will need to bail the defendant for an appropriate period of time. When deciding whether a PTWI should be held, the team leader/DCP should consult a designated PTWI prosecutor on his/her views (the referring prosecutor should also be included in this process if practicable).

Arranging an interview

Children and other vulnerable witnesses

Where the witness is a child or vulnerable adult witness, special care must be taken when deciding whether to hold a witness interview. Generally, further interviews with children or vulnerable adult witnesses should be avoided, to prevent trauma from repetition of the account. Where a further interview is unavoidable, you should first consider whether that could be undertaken by the original interviewing police officer, who will already have established a rapport with the child or vulnerable adult witness.

If, having considered all these factors, you decide that a pre-trial witness interview should take place you should go on to consider the age, degree of vulnerability and status of the witness before reaching a final decision. This should be done in consultation with the SIO/OIC.

Consultation with others on holding an interview

When a decision has been made in principle to invite a witness for interview, you must advise the officer in charge of the case and seek his/her view on the merits and practicalities of conducting an interview.

If the police are opposed to a pre-trial interview taking place, the officer in charge must set out his/her reasons in writing. If, having considered the police objections, you want to proceed with the interview, you must discuss it with your line manager (normally DCP or Unit Head). It may be appropriate to seek the views of a senior police counterpart but the decision whether or not to conduct an interview will rest with the CPS.

If Counsel has been instructed in the case, Counsel's views on the need for a pre-trial witness interview will be sought. Similar arrangements will apply if the case has been allocated to a CPS Higher Court Advocate (HCA).  

Where you want to proceed against the advice of either Counsel or the HCA, the matter should be referred to your line manager (normally DCP or Unit Head) and where appropriate, to the DCCP or CCP.

Contacting the witness

Initial contact with the witness should be made through the police and should be followed up with a letter which can be accessed here, enclosing an explanatory leaflet (English, Welsh), setting out the purpose of the interview. Ideally, the officer in the case will be responsible for delivering the letter and leaflet to the witness.

In some cases it may not be practicable for a police officer either to make early informal contact with the witness or deliver the letter. In such cases, the letter should be sent to the witness either by the prosecutor or (post charge) the Witness Care Unit (WCU).

The advantage of using the WCU is that they will already have established some rapport with the witness. The prosecutor must liaise with the WCU officer to discuss the issues and agree responsibilities before the witness is contacted about the PTWI.

The leaflet covers most of the issues, but some points will have more impact if they are contained in a letter from the prosecutor making the request.

It is both good practice and courteous to let the witness know why they have been asked to attend an interview with the prosecutor.

The letter should introduce you and set out:

  • the purpose of the interview;
  • where the interview will take place;
  • how long the interview is expected to take;
  • who will be present;
  • practicalities (location of the office, parking, payment of expenses);
  • point of contact for the witness to call if the witness has any queries (usually WCU or contact nominated by the reviewing lawyer).

The witness may bring a supporter with them but it should be made clear that the prosecutor has the final discretion on who can attend the interview and that the supporter must not be a witness in the case or a potential suspect. The witness should be asked to provide the name of the supporter in advance of the meeting. This will give the SIO/OIC an opportunity to confirm whether the supporter is connected with the case in some way.

The SIO/OIC should have apprised you of any special needs or disabilities that may affect the location where the interview is to take place, but if not, make sure this is checked and sorted in advance of the interview.

Where the witness is a child under the age of 13 the letter should be addressed to the parent(s) or guardian(s). Where the child is 13 - 16 years of age each case should be considered separately, following discussions with the SIO/OIC. In most cases there will be no problem informing the parent(s)/guardian(s) but there may be some cases where the child alone should be written to.

Witnesses cannot be compelled to attend a witness interview. If a witness fails to attend, or indicates that he/she will not attend, ask the police to ascertain why this is so. You should not automatically assume that non-attendance means the witness is unreliable or hostile. There may be a good explanation as to why they have not attended, from cultural barriers to fear of the defendant.

Arrangements exist for advance payment of expenses when a witness cannot afford to travel to court. The same arrangements can be utilised for a witness attending a pre-trial interview.

The defence should normally be made aware of any failure on the part of the witness to attend the interview in accordance with the prosecutor's disclosure obligations.

Interpreters and intermediaries

If an interpreter or intermediary is required to attend the interview (whether or not one was used when the original statement was taken), the CPS should arrange and pay for a suitably qualified person to attend the interview.

Potential witnesses must not act in the role of interpreter or intermediary, but a person who assisted in the taking of a witness statement may assist at a witness interview. Refer to existing guidance on the selection of interpreters for further detail.

Preparing for the Interview

Practical issues

In most cases the interview will take place on CPS premises, although it can take place elsewhere, (such as at a police station) if it is necessary or desirable to do so for reasons of security or accessibility.

With the exception of children or vulnerable adult witnesses all PTWIs must be audio recorded on tape.

For children and vulnerable adult witnesses whose original evidence has been visually recorded, section 9 of the Code of Practice provides that the pre-trial witness interview should be visually recorded.

In the case of other adult witnesses whose original evidence was visually recorded, the Code of Practice provides that the pre-trial witness interview may be visually recorded. Where the facility is available and it is practicable to do so, prosecutors should record the interview visually rather than in audio.

In such cases the interview should normally take place at a police interview suite specifically set up and equipped for interviewing such witnesses.

The rationale for visual recording is consistency of approach. The witness will be familiar with the video suite and the process of video-recorded interviews.
Pre-trial witness interviews may be conducted remotely, although where possible this should be avoided. However, there will be cases where a remote interview is the best that can be achieved. In such cases the prosecutor may use his/her discretion to conduct an interview by indirect means such as a telephone or video-link. The prosecutor must ensure that the interview is audio or visually recorded in compliance with the Code of Practice.

If a face to face interview takes place you should ensure that the room is tidy. Think about your own personal safety. Make sure that, so far as is practicable, the room is empty of items that can be thrown or used as a weapon.

Detailed guidance on this can be found in the CPS/DTUS protocol on health and safety.

Police officers are not required to attend witness interviews as a matter of routine, but if you consider that the presence of a police officer may assist in putting the witness at ease or assist in relation to any issues that may arise or if you have real concerns that the witness may pose a risk to your safety, you should discuss the issues with the SIO/OIC. If necessary, request the attendance of a police officer at the interview. The officer attending should be familiar with the case but play no part in the questioning process.

If the police refuse to allow an officer to attend where you consider it necessary, particularly for reasons of personal safety, refer the issue to your DCP/Unit Head.

You may also want another member of CPS staff present for administrative support. Whoever you choose, make sure that they are willing and able to attend and their line manager has consented. In advance of the interview brief the nominated person on what is required of them.

If feasible, it is helpful for the reviewing prosecutor or trial counsel to be present at the interview. They can make their own independent assessment of the quality of the evidence. If they have been trained to conduct pre-trial witness interviews they may ask questions as well, but it must be clear to the witness who is leading the interview. As a general rule it is preferable for the lead interviewer to ask all the questions.

Ensure that the respective roles are established in advance of the interview. If the other prosecutor wishes to ask questions, ensure that he/she is fully conversant with the evidence in the case, has discussed in detail with you the issues in advance of the interview and has participated in planning the interview including deciding on the questions that are to be asked.

Where you are also the reviewing prosecutor, you may want a fellow prosecutor to attend the interview as an observer to provide a second view of a witness.


You should have a detailed knowledge of the case.  An interview should only be held if you have a full evidential statement from the witness.

There will be cases where new and unexpected evidence comes to light that could not reasonably have been foreseen. In such cases a second interview may be unavoidable, but you can avoid an unnecessary interview in most cases by waiting until all the key evidence is in.

You should satisfy yourself of the elements of the offence that need to be proved. Establish which witnesses prove which elements. Keep in mind the possible defences to the charge. Often you will have a fair idea of the defence from the interview or the circumstances of the offence. The defence may have put you on notice in general terms. If, for example, the defendant is putting forward an alibi, you may decide that you need to question the witness in detail about the time and place of the offence.

You should go through all the key witness statements and cross-refer them. You should note who corroborates who and any inconsistencies or gaps in the evidence. Check to see that all exhibits are exhibited by the correct person.

In preparing to interview the witness you will need to ensure that you have considered the source, reliability and admissibility of the evidence he/she has to give and question the witness accordingly. If, for example, the witness says "John was hit on the head by D with a bottle", you should ask the witness if he/she actually saw this happen. It is surprising how many times this turns out to be hearsay.

Post Interview

Following the interview, you should make a file note to the effect that the interview took place, who was present etc.

You may need to run off more copies of the tape for the police and for disclosure purposes. You must ensure that the master tape and working copy are properly labelled so the tape can be identified, logged into some form of record and filed securely. 

If further evidence has come to light and no police officer was present, you should inform the SIO/OIC and ask them to take another witness statement or conduct another video interview as appropriate. You should ensure that they have a copy of the tape of interview before doing so. The police should be advised to listen to the tape and use the relevant contents of the tape as the basis of the draft statement.

Disclosure of unused material

The disclosure officer should be notified of any unused material generated through this process and will record it on the appropriate disclosure schedule.

The record of a pre-trial interview will generally be unused material and disclosure should be determined by the application of the appropriate statutory test(s). A record of the pre-trial interview will normally meet these tests and - subject to the application of public interest immunity - the recording of the interview will be supplied automatically to the defence as unused material. The defence should be required to sign the undertaking.

No transcript will be prepared, unless in rare cases, this is necessary for PII purposes because the tape cannot be disclosed to protect the identity or safety of the witness or others.

Security and archiving

Logging and storage

One of the two audio recorded tape cassettes should be designated as the master tape and sealed using the printed label. It should be stored in a secure cabinet until required at court or the conclusion of the case (including any appeal period). A log should be maintained of all audio/video tapes. All CPS Areas have secure cabinets for the storage of child witness video cassettes and other sensitive material and these should be used for this category of tape. 

Where the PTWI has been visually recorded, the master video tape should also be sealed, logged and retained in the secure cabinet.

Retention and destruction

With regard to retention, the master/copy tapes and log entry need to be retained for the same period as the file itself.  With the exception of Long Term Interest cases/double jeopardy cases, tapes should be marked with the appropriate destruction date and continue to be retained separately from the file for the relevant period.  Disposal of tapes should be handled by Iron Mountain Secure Destruction who can provide a special service.  Under no circumstances should the tapes be disposed of as documentary waste or by being manually broken up.

On conclusion of cases categorised as Long Term Interest, the tapes should be sealed in a bag and securely attached to the case file for transmission to the Records Management Unit.  In relation to files categorised as potential double jeopardy criminal cases as per the retention schedule (from April 2008) and stored locally, again the tapes should be sealed in a bag and attached to the case file for retention for the requisite 25 year period.  Upon final review the tapes should be manually extracted and appropriately disposed of as outlined above.

Transmission of tapes

Transmission of tapes to Prosecution Counsel and/or Defence advocates should be approached by using the same secure methods of services using the guidelines relating to sensitive information.

Useful Documents

Pre-Trial Witness Interviews Code of Practice

Witness leaflet (English)

Witness leaflet (Welsh)

Template Letter to Witnesses

Referral Form

CPS/DTUS Protocol on Health and Safety

Flow Chart

Audio Tape Recording Guide

Master Tape Seal

Master Tape Control Log

Pre-Trial Witness Interview Aide-Memoire

Undertaking - Audio Recorded Interviews

Undertaking - Visually Recorded Interviews


Annex A - Flow Chart

Pre-trial witness interviews flow chart

Annex B - Detailed Guidance

Pre-trial witness interviews - detailed guidance for prosecutors on conducting interviews

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