Last week the BBC reported that The Met was trialling a new system which enables officers to extract data stored on suspects' mobile phones at specially-designed terminals in police stations.
However, privacy campaigners have raised concern around the force's retention of that information, after The Met suggested that information collected from suspects is not necessarily deleted in circumstances where no charges are ever brought against those individuals.
Under the Human Rights Act individuals are guaranteed the right to privacy surrounding their communications other than if a public authority, such as the police, believe it necessary to interfere with that right "in the interests of national security, public safety or the economic well-being of the country, for the prevention of disorder or crime, for the protection of health or morals, or for the protection of the rights and freedoms of others".
In a statement sent to Out-Law.com The Met has said that the data extraction technology can only be used in select circumstances and that information is only stored about individuals for as long as can be justified in accordance with guidelines on the management of police information.
"The mobile phone reading equipment is only used to analyse phones of people in police custody who have been arrested on suspicion of committing an offence where it is suspected that the phone has been used in the commission of that offence," The Met said.
"The data recovered via the mobile phone readers is retained and only accessible on a restricted basis to a small number of accredited and trained officers, whose interactions with the data are audited and kept under review. Information and data recovered by police, which supports the investigation or prosecution of a crime will be retained in line with our statutory code of practice, namely the Management of Police Information (MoPI)."
"Holding and properly using intelligence is a key part of fighting crime, pursuing offenders and protecting the public. We acknowledge peoples' concerns about us retaining personal data but we reassure them that information held by the police is subject to our legal and moral duties; is safeguarded by strict guidelines and policy; is auditable, and subject to continual review," it said.
Under The Met's code of practice on the management of police information and related guidelines, information collected as part of police investigations can be held for as long as is necessary and proportionate for the force to retain it. Providing it is "necessary, adequate and up-to-date" personal records are stored for at least six years.
The guidance provides "presumption in favour of retention" of individuals' records as long as the retention of the data is not "excessive" and it is "necessary for a policing purpose, is adequate for that purpose and is up to date". An assessment must also be made about the risk of harm that individuals pose when determining whether it is legitimate for personal records to be retained, whilst the storage must also comply with the principles of the Data Protection Act (DPA). Those principles require, amongst other things, that personal data processed is not kept for longer than is necessary for the purpose for which it was first obtained.
Privacy group, Big Brother Watch (BBW), said it believes The Met's data retention plans when using the new technology is unlawful. It said it has asked the UK's data protection watchdog, the Information Commissioner's Office (ICO), to look into the issue.
"We have written to the ICO to urge them to investigate the data protection law implications of such technology being employed by the police and whether indefinite retention is, as we believe, an infringement of the law," Nick Pickles, director of BBW, said in a blog.
"The courts have clearly said indefinitely retaining personal information is not acceptable and it appears the Met are flagrantly disregarding the law. Where someone is not convicted of a crime it is absolutely wrong for the police to hang onto the contents of their phone," he added.
An ICO spokesperson told Out-Law.com that the watchdog is checking that The Met's practices comply with data protection requirements.
"Any personal information taken from an individual’s phone or other possessions and then held by the police during an investigation would have to comply with the Data Protection Act - including its requirement to process personal data fairly and lawfully, not hold excessive or irrelevant personal data or hold it for longer than necessary," they said. "We are currently making enquiries with the Metropolitan Police Service to ensure it complies with the Act."