Leading article: Undesirable and unproven

The prospect of 90-day detention without charge for terror suspects has made an unwelcome return to the political agenda. Three of the most senior members of the Government - Tony Blair, Gordon Brown and John Reid - have all indicated in recent days that they want to see a dramatic extension of the police's powers in this respect. Legislation is expected soon.

This is odd because no new justification for such an infringement of our civil liberties has emerged since the Government's failed attempt to push this draconian piece of legislation though Parliament last year. We have learnt of no instances in which the requirement for the police to charge or release a suspect within four weeks - the present limit - presented a potential danger to the public.

In the absence of any new security justification for the re-emergence of this issue, we are left with the unsavoury taste of a government exploiting the threat of terrorism for party political advantage. It is hard not to suspect that the scramble by senior ministers to profess their belief in the need for 90-day detention is an attempt to portray the Conservatives, who have consistently opposed the new police powers, as being "soft" on terrorism.

Even Lord Goldsmith, the Government's chief legal adviser, has admitted that he is not convinced of the need for 90-day detention. Lord Goldsmith is, however, in favour of granting the police new powers in other respects. He argues they should be allowed to interview suspects after they have been charged. This is a more complex proposition. Allowing for a greater degree of post-charge questioning for suspects would undoubtedly be preferable to extending their detention without charge. But it would still be undesirable.

Under the 1984 Police and Criminal Evidence Act, a suspect cannot be interviewed after they have been charged, except under special circumstances. There is a reason for this. There is a danger that suspects can be charged with relatively minor offences and then harassed by police to admit to graver ones. We have seen in the past five years how the police have arrested people under anti-terrorism legislation but eventually charged them with unrelated immigration offences. This should serve as a warning of how new police powers introduced in the name of combating terror can be abused.

Ultimately, handing sweeping new powers to the police is not the key to thwarting terrorism in Britain. Amid the growing political clamour, we must remember that those involved in plotting to murder their fellow citizens can be brought to trial in the traditional way - and under existing laws.