I have never had time for privileged people in safe countries who announce that they cannot see the difference between democracy and dictatorship. I gave up on Amnesty International when it said that Guantanamo Bay, in which the guards killed no one, was the modern equivalent of Stalin's Gulag, through which the secret police killed millions. Tory writers strike me as hitting similar peaks of vacuity and delirium when they claim that New Labour is 'Zanu Nu-Lab'.

Can we agree that Britain is not Zimbabwe and then say: 'So what?' The unelected Robert Mugabe is worse than the unelected Gordon Brown, but that does not excuse the assaults on the rights of Parliament and the freedom of the press. Indeed, the descent into hyperbole plays into Brown's hands and allows him to dismiss valid criticisms as hysteria.

We should learn from the great Zimbabwean journalist Trevor Ncube, who argued that the defining feature of Zanu-PF leaders was the secret knowledge that they were political bankrupts. It produced a desperate anger, he said. 'And in their desperation, they are trying to find scapegoats; they're hitting out at anybody.'

The rage of frustrated rulers unites Britain and Zimbabwe rather than political methods. The state went for Damian Green, not because there were serious allegations of corruption against him, as there were against Labour officials, but because the Conservatives had made serious accusations of incompetence against the Home Office.

The outrage that followed has been heartening - did David Normington, the Home Office's Permanent Secretary, and Assistant Commissioner Bob Quick of the Met not know that Charles I lost his head after sending troops into Parliament? But it missed a wider threat.

On the same day anti-terrorist officers deigned to release a leading opposition politician from nine hours of house arrest, Mr Justice Southwell threw out the police case against Sally Murrer, a journalist on the Milton Keynes Citizen - a fine local newspaper, but not one which ever expected to be on the front line of the battle for British liberty.

Like Green, they went after her for exercising freedoms previous generations took for granted. Like Green, they accused her of 'aiding and abetting misconduct in a public office', the catch-all the Crown Prosecution Service has invented to get round statutory protections for whistleblowers who bring news Parliament and the public need to hear. Unlike Green, however, her prosecution makes no sense.

The government's critics think they have a rational explanation for the behaviour of Normington and Quick. A source in the Home Office had told Green that officials had cleared illegal immigrants to work as guards at government buildings. Admittedly, when anti-terrorist officers arrested him, it was the first time they had held a suspect for trying to protect national security. But their motive was clear. Green had embarrassed the Home Secretary and made Home Office civil servants look idle fools. He and his source had to pay.

The accusations against Sally Murrer, on the other hand, were incomprehensibly trivial. The state said that Mark Kearney, a police officer and Murrer's co-defendant, had given her the story that Thames Valley Police did not intend to prosecute the star striker of the MK Dons after a fight in a hotel. It also alleged he had passed on a tip that a man who had been murdered in the town had a conviction for drug dealing.

Journalists in free countries receive similar steers every day. Yet the police bugged her phones, ransacked her home and office, confiscated her computers, interrogated her, humiliated her with a strip search, separated her from her daughters and handicapped son and left her with the threat of a prison sentence hanging over her for 18 months.

She has a conspiracy theory for the mayhem they brought to her quiet life that also touches on the rights of Parliament. She is convinced that the police and CPS were trying to intimidate Kearney into silence because he had protested about his superiors ordering him to bug conversations between Sadiq Khan, the Labour MP and lawyer, and a jailed terrorist suspect.

I find the alternative as grim. It may be that Labour ministers, police and prosecutors regard the release of any unauthorised information, however inconsequential, as a crime and are determined to persecute sources and the politicians and journalists they speak to. The state wants potential trouble-makers to ask themselves once, twice, 100 times if taking on the government is worth the trouble.

Optimists will point out that the judge stopped the trial. But Southwell did so on a technicality and with evident reluctance. He grumbled about being 'forced' to release the accused because he was 'effectively bound' by European law. Then, for no understandable reason, he banned the press from reporting what he had done for three days.

As I have said before, the judiciary is no longer a guarantor of liberty. One of the first acts of President Obama will be to sign a bill from Congress that prevents the verdicts of British libel judges being enforced in the States. American politicians and writers of all political persuasions have been outraged by the behaviour of Mr Justice Eady, who merrily agrees to the banning of books that have never been published in this country and orders the fining of foreign authors. So, too, has the United Nations.

Yet the unprecedented spectacle of America, a fellow democracy whose legal system has roots in the English common law, deciding that Britain is no friend to freedom of speech, has passed without comment from officialdom here.

Such silences are becoming an ominous feature of bureaucratic life. Listen as hard you like, but you will never hear a Law Lord tell Eady that he cannot censor writers at the behest of plutocrats, or New Scotland Yard and the Home Office tell Quick that he cannot arrest opposition MPs, or the CPS tell Thames Valley detectives that they cannot harass an innocent reporter.

No one in authority ever seems to say to the bewigged authoritarian or uniformed goon: 'This isn't Zimbabwe, you know. This is Britain and you just can't do that here.'