Under the Investigatory Powers Act 2016, nicknamed the 'Snoopers Charter', communications companies can be required to retain customers' communications data for up to 12 months. The government describes communications data as the who, where, when, how, and with whom of a communication, but does not include what was written or said.

But in December last year the European Court of Justice (ECJ) ruled that the powers of the UK's surveillance legislation were too wide and did not comply with EU law.

In response to the ECJ ruling, the government now plans to make a number of changes, such as introducing a new independent body to authorise communications data requests. Previously, senior police were able to authorise requests.