Police forces have begun trawling through crime and counter-terrorism intelligence reports after faulty mobile phone data is believed to have been submitted as evidence in criminal cases for over a year.
It is understood experts are now manually checking databases for information provided by O2, amid concerns the problem could cause trials to be further delayed or convictions challenged.
The telecoms provider, which is the largest in the UK with over 23 million customers, informed police chiefs that there were concerns about the accuracy of information it was providing to forces in February.
But the bug has been in the system for over a year and is understood to still not be fixed.
Lawyers have complained that they have not been formally told about the issue, despite the Home Office launching a major investigation.
The fault relates to a phone’s unique International Mobile Equipment Identity (IMEI) number, which can be used by police to track a handset even if the SIM card has been removed and swapped.
The problem could mean inaccurate information about calls a defendant made or received is presented to juries.
It could also impact the reliability of location data used to pinpoint where an accused person was when a crime was committed.
In 2020 the Home Office reported that communications data had played a role in all counter-terrorism operations over the past decade and is used in the majority of organised crime investigations.
Jessica Sobey, Barrister at Stokoe Partnership Solicitors, said: "Hot off the heels of the bullish prosecution of sub-postmasters in the Horizon scandal, reports of faulty mobile phone data being used as evidence in criminal cases for over a year demonstrates a systemic issue with the way in which digital evidence is treated in courts.
"With hundreds if not thousands of convictions hinging upon call data records and locations obtained from faulty software, the need for further scrutiny on the presumed reliability of computer based systems and the ‘evidence’ that they produce cannot be understated.
"Whilst it is not known at this stage how far reaching the recently announced Home Office probe will be, it is vital that it delivers results."
But the Criminal Bar Association (CBA), which represents barrister in England and Wales, said it had not yet been made aware of "any alleged deficiencies in data records made available by mobile phone network operators to police and prosecution authorities".
CBA chair Tana Adkin KC added: “Members of the independent criminal bar defend and prosecute a range of serious offences in our courts and rely on evidence served under strict rules of disclosure.
“The CBA looks forward to any updates from the relevant authorities, including the Home Office, on mobile phone data in criminal proceedings to ensure ongoing compliance with the disclosure rules."
Detectives require permission from a senior officer and the Office for Communications Data Authorisations (OCDA ) to access a person’s phone data, but do not require a warrant.
The OCDA approved more than 250,000 requests for communications data from forces in 2022, according to the Investigatory Powers Commissioner's Office.
A Home Office spokesman said: “We are aware of an issue involving a telecommunications operator which has affected the provision of communications data.
“We are working with the relevant organisations...an investigation is ongoing.”
An O2 spokesman said: "We take this matter very seriously and we have notified the relevant bodies, taken steps to help mitigate against a recurrence in the short-term and our teams are currently working to determine the facts and fully resolve any issues as a top priority.”
