Leading article: There is no excuse for this attack on civil liberties

The Government won a division on the creation of a new offence of "glorifying" terrorism by one solitary vote. Labour's 66 majority all but evaporated. It is a sign of the times that John Denham, the former chairman of the Commons Home Affairs Select Committee, led the charge against this new offence. This robust stance by one of Mr Blair's former allies in defence of civil liberties makes the absence of two Liberal Democrat MPs, Vincent Cable and Alan Beith, from Wednesday's debate all the more reprehensible. Protecting civil liberties is supposed to be the raison d'être of the Liberal Democrats. Had these two MPs voted, the Government might have been defeated. If, as has been suggested, Mr Cable has aspirations to lead his party, he will need to raise his game. Also notable by his absence was the Respect MP George Galloway. One might have expected this avowed critic of Tony Blair to have relished inflicting a defeat on the Government.

But in any case, this near miss was enough to prompt the Government to retreat over its proposed 90-day detention period for terror suspects. There is now talk of a compromise. The Home Secretary, Charles Clarke, has promised to present revised proposals to the Commons next week. One proposal is to allow the police to hold suspects for just 28 days. But even that is too long. The fact that suspects can presently be held for two weeks without charge in Britain is already exceptional in Europe. Any extension of this will effectively create internment. The effect of this will be the alienation of communities and an increase in support for fanaticism. The great danger is that whatever is settled upon as the maximum detention period will, in fact, become the standard. What incentive will the police have to release someone before they are legally obliged to?

Mr Clarke has been trying to win support for his Bill by arguing that these new powers will only be used "in a tiny number of cases". This is not comforting. Parliament has a duty to scrutinise each piece of legislation purely on its merits. MPs cannot be expected to accept guarantees that new powers will be used responsibly. Even if they do trust the Government of the day, a future administration might not be so responsible.

It is heartening to see that the Commons has realised the folly of outlawing the "glorification" of terrorism. This part of the Terrorism Bill is badly drafted, illiberal nonsense. It turns out that it would affect anyone who advocates violent resistance to despotic regimes around the world. It could even be retrospective, criminalising - in theory- someone who had expressed support for the actions of the African National Congress during apartheid.

In the end, the Bill - minus the glorification clause and with a reduced detention time - may get past the Commons with Tory support. But this would be very damaging politically for the Prime Minister. And it is, in any case, unlikely to get past the House of Lords.

We must accept Mr Blair and Mr Clarke at their word when they claim to have been persuaded by the police and the security services about the need for these new laws. But that does not make these restrictions on our civil liberties justified. Nor does it mean that the security forces are necessarily right. The new powers created by this Bill are likely to be - at best - an irrelevance to our society's efforts to defeat terrorism. At worst, they could make the job much more difficult.