Leading article: The steady erosion of our civil liberties

The return of the discredited methods of stop and search to British policing is most disturbing. Home Office figures show that the number of people being stopped and searched has risen twentyfold in six years. Last year some 100 people were being stopped each day. Why has a technique so long associated with heavy-handed policing - and widely blamed for exacerbating racial tension - been allowed to return? For the answer we must look to the Government's creeping authoritarianism and the opportunity afforded to illiberal ministers by the heightened terrorist threat.

Since the end of the old "sus" laws, the police must have a reasonable suspicion that someone has committed an offence before they can stop and search them. But the Terrorism Act, passed in 2000, shifted the ground back again. This grants police the right to stop anyone in an area designated as being under threat of terrorism, regardless of whether there is any reason to suspect that person of a crime. Senior police officers can authorise the use of such powers in specific areas for up to 28 days. More than 1,000 orders to establish such areas have been given the go-ahead in the past six years. Ministers, in fear of terrorist attacks, have even encouraged the police to exercise these new sweeping powers, particularly since the July 7 bombings in London.

The result is that numbers of stop and searches has risen sharply. And unsurprisingly, ethnic minorities are being disproportionately targeted again. One in five of those stopped last year was black or Asian.

If stop and search was succeeding in apprehending terrorists, a defence of the tactic might be mounted. But there is no evidence that this is the case. Only 455 people, out of more than 35,000 stopped and searched, were arrested last year through these powers. A small number of these arrests were for terrorism-related offences. But no terrorists themselves were stopped in this way. And there is certainly no reason to believe that major plots have been foiled by these methods. A large number of the arrests were for motoring offences. The reality is that stop and search has become a way for the police to harass innocent members of the public.

This law has been abused in other ways too. There are disturbing indications that it has been used to suppress legitimate political demonstrations. A stop and search zone was used to disrupt protests at an international arms fair in east London in 2003. And we should not forget the treatment of Walter Wolfgang, the pensioner who was arrested under this law after he heckled Jack Straw at last year's Labour conference.

No one would dispute that the police need some discretionary powers, but they cannot be as broad-brush as this law allows. Even Lord Carlile, the Government's independent adviser on terrorism legislation, believes that the use of stop and search could be halved without reducing public safety. Today the House of Lords will, rightly, try to tighten the legislation to limit the power of police to authorise blanket stop-and-search operations.

In recent years we have also seen the surreptitious creation of a DNA database and an explosion of anti-terrorist legislation, and now we are facing a national ID card scheme. Lord Falconer has let slip that the Government wants such cards to become compulsory. All this, combined with the powers of stop and search, means we could soon find ourselves in a position where we have to justify our existence to the state, rather than the other way round. This cannot be tolerated.

A tension between national security and civil liberties is to be expected. But the Government is taking this country down a road that will not only leave us less free, but less safe as well.