What did they do?

In 2012 Detective Inspector Tony Rock was instructed to conduct an investigation into leaks to the media by then-chief constable Jacqui Cheer. There were three leaks, one regarding an internal grievance, one regarding a confidential report regarding racism within the force, and another which related to information about a murder - information which had not even come from a police officer.

He used the RIPA law to look at the calls and text messages of six individuals, including two Northern Echo reporters, Graeme Hetherington and Julia Breen, a national newspaper journalist Jeremy Armstrong (although the force had in error submitted his number under a third former Echo reporter's name, Chris Webber), two serving officers, Mark Dias and Steve Matthews, and a solicitor. The seven RIPA applications, made over a four-month period, were signed off by the force's current head of crime, Detective Superintendent Peter McPhillips.

The Northern Echo:

Mark Dias

Why was it unlawful?

RIPA as a law gives police and other public bodies special powers to look at communications data – but it was only designed for use in investigating terrorism and other serious crime and should not be used lightly.

Cleveland Police claimed they had legal advice from the force's solicitor Julia Hatton which said that a crime of misconduct in public office had been committed if the serving officers were found to have leaked the information to the Echo.

However, judges found that the email from Julia Hatton did not constitute official legal advice. They also argued Cleveland Police should have looked at other ways of investigating the leaks before resorting to seizing phone records.

The Northern Echo has also discovered that the Crown Prosecution Service emailed DI Rock on July 16 advising him there was no further action to be taken in a criminal investigation against Mr Dias. Yet over the next week, another two RIPA applications were authorised. The investigation into Mr Matthews was ongoing until 2013 – but some of the applications related to the leak Mr Dias had already admitted being responsible for. It also emerged that DI Rock himself admitted he was "unsure" if any criminal offence had been committed as he applied for RIPA.

DS McPhillips, "contrary to what we would expect from a competent and properly trained designated person", judges said, had not considered the European Convention on Human Rights namely the right to privacy and the right to freedom of speech which offers special protection for journalists.

Which officers were responsible?

There were 47 officers in the Professional Standards Department at Cleveland Police at the time, but not all were involved. Detective Constable Geoff Cox, now retired, was tasked with making the RIPA applications by DI Tony Rock, also now retired, the officer investigating the leaks. Cleveland Police's current head of crime Detective Superintendent Peter McPhillips, the "designated person" had authority to sign them off, which he did. However, it emerged yesterday that Chief Constable Jacqui Cheer ordered the investigation, and was being briefed on its progress, although there is no clear evidence she was aware of the unlawfulness of the RIPA authorities.

Will there be a criminal investigation?

Cleveland Police said it was bringing in another police force to investigate whether there was any criminal or misconduct matters. However, retired officers cannot be brought back to face misconduct proceedings, so if no criminality is found, they will not face discipline.

Could Cleveland Police still be monitoring journalists' phones?

A change in the law in 2015 means police forces now need a judge's approval to look at journalists' phone records in an attempt to find a source. Chief Constable Iain Spittal has said there has been no use of RIPA legislation since he joined the force in 2013 to identify the source of leaks to the media, or to target journalists going about their work.