The Sadiq Khan affair has killed stone dead the thesis, beloved of Tony Blair and Gordon Brown, that any accretion of power to the state is sustainable because ministers are in control. Whether this applies to phone tapping, bugging devices, ID cards, NHS records, childcare computer systems, video surveillance or detention without trial, it is simply a lie. Nobody can control this torrent of intrusion. Nobody can oversee a burst dam.

Khan, an MP and government whip, was allegedly targeted by the police for having been a "civil rights lawyer" and thus a nuisance, though the recording of his meetings with a constituent in prison was supposedly directed at the inmate. Either way, the bugging destroyed the "Wilson doctrine", that MPs cannot be bugged. It appears that they can if ministers, or the police, so decide.

Security machismo claims that in the "age of terrorism", real men bug everyone and everything. The former flying squad chief and BBC dial-a-quote, John O'Connor, implied this week that it would be negligent of the police not to bug anyone they - repeat they - thought a threat. The Blair thesis that "9/11 changes everything" has been a green light to every security consultant, surveillance salesman and Labour minister wanting to flex his - or her- muscles in the tabloids.

Years ago a lawyer gave me unassailable evidence that a call with a client had been tapped by the police and handed to the prosecution. Such tapping allegedly required a personal warrant from the home secretary who, when tackled on the subject, flatly denied it could have happened without his approval, which he would never give in such a case. I checked back with a police chief, who roared with laughter. "The home secretary is absolutely right. He must authorise all taps sent to him for authorisation. But not, of course, the rest." Orwell's cuttlefish were squirting ink.

The grim reality of the past week alone is that it has seen a substantial section of the British establishment allowing itself to believe that private dealings between lawyer and client, and between MP and constituent, should no longer be considered immune from state surveillance. A cardinal principle of a free democracy is thus coolly abandoned. It is not a victory for national security. It is a victory for terrorism.

The monitoring organisation Privacy International now gives Britain the worst record in Europe for such intrusion, indeed the worst among the so-called democratic world and on a par with "endemic surveillance societies", such as Russia and Singapore. The Thames Valley policeman, Mark Kearney, who bugged Khan's conversation in Woodhill prison, claims to have protested that it was "unethical" but was overruled and placed under "significant pressure" from the Metropolitan police. He has since had to leave the force. The saga reads like a script from the film about East German espionage, The Lives of Others.

Britain's poor record is the result of government weakness towards the security apparat. Even among supposed liberals, the response is to demand not less surveillance but more oversight. David Davis, the Tory spokesman, said yesterday: "It's got to be controlled; it's got to be accountable." Civil rights champion Liberty wants "simpler and stronger surveillance laws, with warrants issued by judges, not policemen nor politicians".

People have been saying this for years. Britain has a Kafkaesque oversight bureaucracy ranking with the one it purports to oversee. Some six separate surveillance monitors trip over themselves. All operate in secret and appear to be one gigantic rubber stamp. The distinction drawn by the justice secretary, Jack Straw, between "intrusive" and "directed" bugging, illustrates the prevailing mumbo-jumbo. The chief surveillance monitor, Sir Christopher Rose, has been asked by Straw to investigate the Khan affair, which appears to be a failure by the chief surveillance monitor. Is this to be taken seriously?

When the council can bug you for fly-tipping, when prisons can record conversations with defence lawyers, when any potentially criminal act can justify electronic intrusion - and when ministers resort to the dictator's excuse, "The innocent need not fear" - warning bells should sound.

There is no "balance" to be struck between civil liberty and national security. Civil liberty is absolute, security its handmaid. Measures are needed to protect the public, but a firm line needs to be drawn round them. The line must accept a degree of risk, or a police state is just around the corner.

A quarter of a million surveillances in Britain are beyond all power of politicians or overseers to check. It is state paranoia, justified only by that catch-all, the "war on terror". In truth it is not countering terror, but promoting it. Mass surveillances one of the poisons that the terrorist seeks to inject into the veins of civil society.

It is clear the overseers have gone native. Even the "independent" security watchdog, Lord Carlile, has bought 42-day detention. More oversight will not cure surveillance but mask its spread. The extension from terrorism to benefit fraud, fly-tipping and trading standards demonstrates how the official mind flips to Stasi mode at the least excuse.

To claim that Britain is a police state insults those who are victims of real ones. But I have no doubt that feeble ministers are slithering down just this road, pushed by the security/industrial complex. It is not oversight that must be increased, but rather the categories and boundaries of surveillance that must be drastically curbed.

Of course there are people who want to explode bombs in Britain. Taxpayers spend a fortune trying to stop them. But how often must we remind ourselves that the bomber need not kill to achieve his end when we appease his yearning for the martyrdom of repression? The amount of surveillance in Britain is grotesque. It is a sign of the corruption of power, and nothing else.