The police appear to have declared war on journalists. If this sounds more than a little far-fetched, consider the evidence.

Case one: in September, it emerged the Metropolitan police had used the Regulation of Investigatory Powers Act (Ripa) in order to covertly access the mobile phone records of the Sun’s political editor, Tom Newton-Dunn. He was responsible for the controversial Plebgate story in September 2012, which alleged the then government chief whip, Andrew Mitchell, had insulted police officers at the gates of Downing Street.

Case two: in October, it was revealed that Essex police had secretly used Ripa, also in 2012, to hack into the phone records of the Mail on Sunday newsdesk in order to discover how it obtained exclusive articles about the former cabinet minister Chris Huhne. In so doing, the police outed the paper’s source and the freelance journalist, Andrew Alderson, who acted as the go-between. The police did not even keep the details of the calls and emails between Alderson and the paper’s news editor, David Dillon, to themselves; they passed them on to lawyers.

Case three: two weeks ago, six journalists announced they were taking legal action against the Met after discovering officers had been recording their activities and movements on a database that monitors “domestic extremism”. They are Jules Mattsson, a Times reporter; Mark Thomas, the comedian-cum-journalist; three photographers - Jess Hurd, David Hoffman and Adrian Arbib - and Jason Parkinson, a freelance video journalist. Parkinson was astonished to find the police had detailed his movements in 130 entries, including his attendance at demonstrations as a member of the press.

The six, represented by the National Union of Journalists, have launched a legal challenge to the surveillance along with a demand that the Met destroys the files held on them. Some of the group complain that, quite apart from being monitored, they have been persistently stopped, searched and assaulted by police officers. Five of them have successfully sued the police in the past, winning damages or apologies from the force. These frontline confrontations have something of a history, but they are also suggestive of the growing antagonism between officers and journalists.

Case four: last week, the Times reported that the police had examined the phone records of 1,757 staff, including journalists and lawyers, working for the Times, Sunday Times and Sun after the material was mistakenly sent to them by Vodafone. It enabled officers to scrutinise the records to the extent of conducting data analysis and building a spreadsheet before, after several months, they eventually lodged “a formal error report”.

Those four separate incidents certainly go a long way to suggest the police are at war with the hacks. In addition, we should not overlook the matter of the arrests of 25 Sun journalists for alleged illegal payments to public officials, which followed the News of the World phone-hacking drama. Indeed, it was the Met’s embarrassment after being exposed for having failed to carry out a comprehensive investigation into hacking that engendered the opening of hostilities with the press.

It triggered an inquiry, led by the former parliamentary commissioner for standards, Elizabeth Filkin, that registered official concern about the nature of the relationships between police officers, from the highest to the lowest ranks, and journalists. Her inquiry ran in parallel with Lord Justice Leveson’s inquiry into press practices. But Filkin’s report appeared almost a year before Leveson’s and heralded a split between Scotland Yard and Fleet Street. She contended that the previous informal relationships had caused “serious harm”, that information was passed to journalists “inappropriately” and warned of the need to terminate socialising.

The former Daily Mirror crime reporter, Jeff Edwards, said at the time that Filkin’s report appeared to “have taken a sledgehammer to crack a nut”. He foresaw the likely outcome, and it came to pass very quickly. Although her report dealt only with the Met, the Association of Chief Police Officers (Acpo) took the opportunity to publish “guidance” for all police forces in England and Wales. For guidance read rules, which virtually outlawed easy contact between police and journalists. Officers were under no illusion that speaking to the press could cost them their jobs. “All contact,” sad Filkin, “should be available for audit.”

Just as significant was the transformation in internal police culture. It had begun to change with the increasing use by police forces of professional press officers as a buffer between officers and reporters. The chill, as crime correspondents confirm, soon became a deep freeze. Journalists are not getting information and, as one former Guardian crime reporter said, the loser is the public. People are not getting to know as much as they should.

The police have also been subject to criticism in several high-profile cases over the past five years, all of which have resulted in hostile headlines. Among the controversies were the Hillsborough disaster cover-up, the 2009 death of Ian Tomlinson during the G20 summit protests, and the 2011 death of Mark Duggan that resulted in inner-city riots. To add to the toll of negative coverage came Plebgate itself.

Not speaking to journalists is very different, however, from treating journalists as criminals or using their private phone conversations as ways of investigating crime. As many reporters have pointed out, the result will be to scare off whistleblowers. Who will dare to speak to journalists who cannot ensure the confidentiality of their calls and emails? Stories that should be told will not see the light of day. In effect, therefore, the war the police have launched on journalists is really a war on the public’s right to know.