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Guidance on examination of mobile phones in sexual offence cases

In cases where offences such as rape or sexual assault are alleged, disclosure of the content of messaging (in particular) on the complainant’s mobile telephone often becomes a highly relevant issue. Allegations of this nature are often made by those in a relationship with the suspect or there may be significant dispute about consent. Those suspected of such offences will often wish to rely upon messaging between the parties, but also seek to establish whether there is other evidence on the phone which goes to the credibility of the complainant. Such cases often involve the consumption of alcohol and first-hand evidence of the witnesses on both sides can be sketchy. The Police routinely seize devices from those suspected of criminal offences and hence the value of such evidence (often contemporaneous messaging) should not be underestimated.

In R v CB and Sultan Mohammed [2020] EWCA 790, the Court of Appeal heard conjoined appeals by two Appellants convicted of sexual offences. In both cases, messaging on the mobile phones of the complainants was in issue in the case and the subject of grounds of appeal. The Court of Appeal took the opportunity to extract four issues of principle for application on the question of disclosure in cases of this nature:

1. Identification of the circumstances when it becomes necessary for investigators to seek access to a witness’ digital communications and the disclosure of any material extracted.

It was held that there must be ‘good cause’ to review digital material i.e. there must be reasonable grounds for believing that the mobile phone contains material relevant to the investigation. Effectively, the suspect must have raised an issue or issues which mean that extraction of such material is a reasonable line of enquiry. Thus, the importance of raising such issues during the course of an interview under caution and/or later in a detailed defence statement is paramount here. The Court stressed that “mobile telephones or other devices should not be obtained as a matter of routine by investigators from witnesses”.  Moreover, the test for disclosure is that set out in section 3 Criminal Procedure and Investigations Act 1996 namely whether the material is capable of undermining the prosecution case or assisting the defence case.

2. If investigation is necessary how should it be conducted?

The level of ‘intrusion’ into the telephone will again be determined by the facts of the case and the issues identified by the defence. Again, the importance of an early identification of the issues raised by the defence and a comprehensive defence statement should not be under-estimated. It is recommended that the investigating officer should look at the telephone to establish the extent of the review necessary. It may only be necessary, for example, to look at any messaging between the parties. However, if a more extensive enquiry is necessary then “the contents of the device should be downloaded with the minimum inconvenience to the complainant and, if possible, should be returned without any unnecessary delay. If the material is voluminous, consideration should be given to appropriately focused enquiries using search terms, a process in which the defendant should participate”.

3. The reassurance to be provided to the complainant

The Court stressed that “the complainant should be told i) that the prosecution will keep him or her informed as to any decisions that are made as to disclosure, including how long the investigators will keep the device; what is planned to be ‘extracted’ from it by copying; and what thereafter is to be ‘examined’, potentially leading to disclosure; ii) that in any event, any content within the mobile telephone or other device will only be copied or inspected if there is no other appropriate method of discharging the prosecution’s disclosure obligations; and iii) material will only be provided to the defence if it meets the strict test for disclosure and it will be served in a suitably redacted form to ensure that personal details or other irrelevant information are not unnecessarily revealed (e.g. photographs, addresses or full telephone numbers)”.

4. What happens if the complainant refuses to hand over the phone or deletes material?

In such circumstances, the Court will have to make an assessment as to the potential impact on the fairness of the proceedings. The Court retains an inherent power to stay proceedings as an abuse of process where it determines that defendant is unable to have fair trial. However, this is a power that is only used  in exceptional circumstances. The trial judge will need to weigh up the impact of the lack of availability of the subject material on the trial taking into account the evidence as a whole. If it can be rectified by suitable directions or cross-examination then the judge is likely to allow the trial to proceed so that the jury can assess the lack of availability of such evidence in its overall determination of whether the prosecution is able to prove its case to the requisite standard. The reasons for refusal and the potential significance of the material will be crucial here.


There is no automatic right for the defence to inspect the mobile telephone of a complainant in sexual assault or rape cases. The defence will need to establish a proper basis for the police to inspect the phone either through the provision of the parameters of the defence at interview or in a properly drafted detailed defence statement. If there are concerns about the destruction or deletion of material, requests to preserve it ought to be communicated to the police as soon as possible. The police will not be required to download the entire content of the telephone but will make an assessment of the extent of investigation necessary. Once material has been extracted, it will be subjected to a test of relevance and subsequently whether it is capable of undermining the prosecution case or assisting the defence case.


If you are being investigated or prosecuted for an allegation of sexual assault click here to find out how Brett Wilson LLP's specialist criminal litigation solicitors can assist you.


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Articles are intended as an introduction to the topic and do not constitute legal advice.