Seventeen people were wrongfully arrested or had their homes searched last year as a result of serious errors made by the police and security services after they had accessed confidential web and phone data, an official watchdog has revealed.



More than 760,000 items of communications data, which track an individual’s phone and web use, were acquired by police or security services in 2015, according to the annual report of Sir Stanley Burnton, the interception of communications commissioner.

The report, published on Thursday, reveals 1,119 errors made by public authorities in their use of communications data in the calendar year – a 20% increase on 2014.

The watchdog found 23 cases involving serious errors, including nine “technical system errors” that led to 2,036 “erroneous disclosures”. The remaining 14 serious cases were the result of human error.

Burnton’s annual report says the serious errors led to 17 cases in which people who were unconnected to a police investigation were either arrested or had property searched that had nothing to do with the inquiry.

A further six innocent people were visited by police as a result of errors and there were delays to welfare checks on seven vulnerable people.

The watchdog also identified four cases in which communications data was acquired to identify a journalist’s source without judicial authorisation. In one high-profile case, the watchdog found that Police Scotland had acted recklessly after the individuals concerned complained to the investigatory powers tribunal.

In the other three cases the commissioner ruled that the conduct was “not wilful or reckless” and “did not adversely affect any individual significantly”.

Burnton says 145 public authorities had access to confidential data in 2015; 93.7% of applications were made by police forces and law enforcement agencies. The security services were responsible for a further 5.7% of requests and local authorities and other public bodies for the remaining 0.6%.

The report criticises the prison service for not having an adequate translation strategy in place to monitor the calls and correspondence of prisoners using foreign languages. “This was particularly relevant to those prisons with a high proportion of foreign national prisoners where a small number of inspections revealed that staff were being directed to listen to a large number of calls made in foreign languages but were not being provided with any guidance as to whether the calls should be translated,” Burnton said.

“Consequently no benefit was being derived from the monitoring, which undermines the necessity and proportionality for it as the exercise cannot meet the objective for which monitoring was authorised.”



The 761,702 “items of communications data” include “identifiers” such as mobile or landline numbers, email addresses or bank or credit card details. A request for incoming and outgoing call data on a particular mobile phone over 30 days is counted as one item of data.

The watchdog also received 62 reports of errors related to the 3,059 interception warrants, which allow the police and security services to access the content of calls, emails, and other messages.

These ranged from “over-collection and unauthorised selection or examination of material to the interception of the wrong communications identifier or failure to cancel an interception”.

The prime minister, Theresa May, said Burnton’s report – and a second from the intelligence services commissioner – recognised the diligence and rigour of those who use investigatory powers to keep Britain safe. “Both reports contain details of the recommendations that the commissioners have made to continue to improve the way that these powers are used. The public authorities who have received these recommendations will be giving careful consideration to them and how to further improve their processes,” she said in a written statement to the Commons.