May 31, 2024

Cell site evidence: challenging times?

Six years after the game-changer for cell site evidence that was R v Calland, the use of experts - or not - is finally having major repercussions for both sides of the criminal justice system.

Having the UK’s largest team of cell site experts gives us a privileged insight into what is happening right now in the courts when it comes to presenting cell site evidence.

We are seeing cases being put at risk of legal challenge by over-reliance on police analysts where, in fact, opinion evidence or evidence that draws an inference must be delivered by an expert witness. And that risk is real – 86% of our recent cell site instructions have come from defence teams.

We thought sharing the details of just such a case would be helpful in illuminating the realities on the ground.

In April 2024, CCL Solutions Group was brought in to assist in a complex defence case involving the supply of Class A controlled drugs, with cell site data key to the investigation. The prosecution alleged the defendant was involved in the offence due to a mobile phone (not accepted by the defendant) connecting to a cell site near to the defendant’s home address, and the same phone having been in contact with people known to the defendant.

A Police Investigator (not a cell site expert) produced several cell site exhibits and provided statements regarding the call data.

A CCL cell site expert reviewed the prosecution material, raising several issues including:

  • Maps and table presented with no indication of the limitations or uncertainties that are inherent to cell site analysis
  • Inferences made about the meaning of the call data from a person who was not qualified to do so - inferences are opinion evidence and as such must be given by experts
  • Opinions about the data were presented as factual statements

Our expert conducted their own analysis, with their report detailing the limitations, uncertainties and conflicts found in the prosecution material. After receiving the expert report and challenging the prosecution, the defence team later reported that the prosecution submitted no evidence, and the case was withdrawn.

Here at CCL, we serve justice by providing expert cell site witnesses both to the prosecution and defence. Acting impartially, we present the facts and offer expert opinion. In our view, this case offers up two key takeaways for consideration:

Law enforcement – Why jeopardise a prosecution by using analysts/investigators, who, even with the best intentions, are still not sufficiently qualified to comment on such matters? The stated case of R v Calland will be considered and may render your evidence inadmissible or at the very least undermine its credibility.

Criminal Defence/Law Firms – In utilising cell site experts you give your client an advantage by having the evidence thoroughly examined and any deficiencies brought to your attention.

Free CPD offer:

CCL is keen to help those working in the criminal justice system stay alive to the issues around cell site analysis. We offer free CPD sessions and workshops with some of the UK’s leading cell site experts, allowing participants to significantly enhance their knowledge of the subject.

For further information, get in touch with the team at

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