Only the intervention of the Home Secretary or the Mayor of London will deter the Metropolitan Police from legal action to force journalists to reveal sources connected to phone hacking investigations.
Civil rights groups say they will continue to lobby Scotland Yard into reversing what has been called an assault on press freedom, but political and legal sources consulted by The Independent – who asked not to be named – said the Met would not back off, unless ordered by Theresa May or Boris Johnson.
Lawyers acting for the Met are planning to use the Official Secrets Act at an Old Bailey hearing on Friday that, if successful, will require The Guardian to hand over evidence identifying sources of key documents used in the newspaper's phone hacking coverage.
Leading legal figures said The Guardian may have been "caught in the crossfire" generated by the Met's new commissioner, Bernard Hogan-Howe who last week said the relationship between police and media had "gone too far". The court action, according to one senior judicial figure, was "an inevitable consequence of the Met being accused of being too close to the media".
He said: "The allegation levelled against the Met ... on phone hacking is that they were too close, too cosy with the News Of The World. The legal question now being asked is this: does the same not apply to The Guardian about information they may have been given?"
Others suggested a court ruling would test "if the law here is consistent and that ethical standards have been consistently applied".