Helping to reduce the likelihood of witnesses reporting information they have not directly observed.
Witness separation – guideline
Officers and staff should separate witnesses to take initial accounts and make sure they are out of earshot of other witnesses, unless this is not possible.
Sixteen studies tested the effects of a discussion between co-witnesses on recall accuracy. These studies were predominantly conducted in university laboratories using student samples. Fourteen of those studies found that witnesses were significantly more likely to report information they had not directly observed during an event when they were exposed to co-witnesses during or before giving their own account. There was also some evidence to suggest this exposure can lead to an overall reduction in accuracy.
The benefits of witness separation
Separating witnesses can reduce the likelihood of them reporting information they have not directly observed. While this is established practice at the formal statement stage and specifically in relation to domestic abuse incidents, this should also apply to initial accounts generally. It is acknowledged that separation might not always be possible, for example in a street fight involving a group of people where it might not be practical to speak to everyone separately, or where an officer is single-crewed and one or more of the parties is not cooperative. In such circumstances, it may be worth reminding the witness to report only what they have witnessed themselves. However, where possible, separation is likely to be beneficial for the investigation process.
Where all relevant witnesses have yet to be identified, the importance of separating witnesses may be a factor in considering where to take the account, and/or who will be present alongside the witness during it. Persons offering to support the witness during the account may themselves be witnesses. Any person supporting the witness should not be a witness in the case and must not be allowed to prompt or speak for the witness.
Witness separation is also relevant where the account is being taken over the phone, as the caller may be with additional witnesses. The officer or staff may wish to check with the witness at the beginning of the conversation and ask them to move away if they are with someone who also witnessed the event, explaining the reasons for this request.