Cell site: Is there another evidence scandal on the Horizon?.

30 April 2024

The Evening Standard recently reported that a major investigation into the use of faulty mobile phone data in criminal cases has been launched by the Home Office. The problem, which has not yet been resolved, relates to phone data provided to police by O2 and is understood to date back to mid-2022. The issue is reportedly with information relating to a phone’s unique International Mobile Equipment Identity (IMEI), which is a number used to identify individual handsets, and could also impact location data. This should be of great concern to investigators, prosecutors, and defence lawyers throughout the criminal justice system given the widespread use of mobile phone evidence in criminal cases and the risk created by faulty or uncertain evidence being put before the jury.

Cell site in Trials

Many criminal trials involve evidence relating to or derived from mobile phones. Investigators request network providers to provide information relating to particular phone numbers, SIM cards, and even individual handsets, which are identified by their unique IMEI number. Call data records will list the date, time, numbers contacted, type of contact, and the cells that were used to make the contact. Types of contact include SMS, MMS, phone call, or GPRS/internet data use. Mobile phone downloads include the information extracted from the phone itself, such as text messages, images, and information from any apps installed on the phone.

In recent years, the technology of mobile phones has developed almost beyond recognition, and smartphones have the capability to contain hundreds of communications applications which must all be downloaded separately, generating hundreds of thousands of pages of evidence. Technology and law enforcement are in a constant battle for progress, with each trying to anticipate and evade the other. Many high-level criminal groups have turned away from traditional phone technology to the use of encrypted apps, such as Signal and Telegram, and encrypted systems such as Encrochat and SkyECC. Since the French and Dutch authorities independently infiltrated the Encrochat system in 2020, the use of such evidence has been repeatedly challenged in the courts on the grounds of admissibility and reliability. So far, the admissibility of Encrochat evidence has been upheld not only by the domestic courts, but by other jurisdictions including the French Court of Cassation and the European Court of Human Rights.

At trial, investigations into mobile phones translates to, for example, call data records showing contact between co-conspirators, schedules of messages showing discussion of criminal activity, and cell site evidence showing the approximate location of a particular phone at a given time. Such evidence is often analysed against other evidence, such as observations or ANPR, to build a full picture of what a particular individual was doing, where they were going, and their contact with others at a given time. If the wrong information about the IMEI or the location is given, it could mean that criminal conduct is wrongly attributed to the wrong mobile phone and the wrong user. This is very concerning for obvious reasons.


For any evidence to be used in court, it must be relevant and admissible. The burden of proof in criminal proceedings is on the Crown, and the standard is a high one – the Crown must make the jury sure of the defendant’s guilt in order for conviction to follow. There will now be a question mark over all cases involving phone data obtained from O2, the reliability of such evidence, and the safety of any resulting convictions.

The extent of the problem and the number of cases affected has not been disclosed at this time, but it is potentially a huge number given O2’s status as the United Kingdom’s second largest telecommunications provider. On a practical level, it is anticipated that this issue could result in delays to cases, disclosure applications, applications to stay or dismiss, applications to exclude evidence, and appeals against conviction. There is a very real risk of miscarriages of justice, and all parties to criminal cases should be alive to how this issue progresses going forwards.

Libby Anderson.
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