Bruce Anderson: The Government is pursuing the 42-day law for the basest of party political reasons

Ministers are assuring rebels they needn't vote against as the Lords will reject the new powers

Isaiah Berlin came out with the phrase which tells us most about the era we live in: "The great goods cannot always live together." Nowhere is this more apparent than in the area of law and order. The two words trip easily off the tongue – especially a Tory one – as if they were synonymous. Far from it: to assess their competing claims requires unending intellectual debate.

It is true that they were conceived in the same womb, at the dawn of history, as men began to live like humans rather than anthropoid apes, and that they have remained inter-dependent. But as civilisation evolved, so did law and the concept of human rights. The rule of law came to protect the subject from the arbitrary actions of his rulers. Englishmen had rights before they had votes, and it could be argued that rights are more useful.

A vote gives you a tiny power to help elect a government which might seize someone else's property. A right gives you the power to protect your own. Today, Russians have the vote. But we will know that they have made an irrevocable breach with their tyrannical past when the ordinary Russian has the right to a fair hearing in a legal action against his government.

But rights still depend on order. After the right to life, the right to order is the second most important human right. None of the others, including the right to life, could be securely enjoyed in its absence. Oakeshott wrote that civilisation is only a collective dream. Without a well-made bed of order, such sweet dreams would quickly turn into nightmares.

Men cannot procure order for themselves. In order to attain it, they must cede some of their rights to Leviathan, the state. In an implicitly contractual relationship, they trade rights for order. Which rights, what order: how can we constrain Leviathan from unnecessary encroachments on freedom? Those questions are influencing the current disputes on 42-day detention.

The opponents have a powerful point. Such a measure is not consonant with that great, moving and harmonious theme: the liberty of the subject. The proponents have an equally powerful rejoinder. Nor are suicide bombings. But there is one proposition which might command general assent; that no such steps should be taken unless the justification is overwhelming. As regards 42 days, this is far from true. The two principal arguments in favour are deeply flawed, almost as much as the Government's motives.

Those who advocate 42 days tell us that even if it has not been necessary in the past, it may be in the future. So it would be useful to have the legislation on the books, just in case. This is doubly nonsensical. In the event of an emergency which merely required detention, an Order in Council could be promulgated with instant effect, to be followed by a quick Bill. In a more complex emergency, additional detention might not be sufficient. But to envisage every possible contingency would require a measure as sweeping as the old Northern Ireland Special Powers Act, which brought Unionist Ulster into such disrepute (it will probably be revived in the next Queen's Speech, for the entire UK).

There was one eventuality which does merit consideration, although no one wants to think about it, for obvious reasons: torture and the ticking bomb. We catch a terrorist. The authorities think that he knows the whereabouts of a nuclear device whichcould be exploded within hours. What are we entitled to do to him in order to extract information which might save tens of thousands of lives?

It is to be hoped that this problem never arises. It is to be feared in the course of this century that it could do so. The ticking bomb scenario is not suitable for instant legislation and requires forethought. As that would be of no use to the Government's spinners, it is unlikely to happen.

The second argument for 42 days is not only nonsense; it is dangerous nonsense. We are told that terrorists might have complicated computers with information encrypted in Arabic, among other hazards. That is credible. What is incredible is the complacent assumption that we could allow ourselves 42 days to master the material.

If a terrorist suspect is worth detaining for four days, let alone 42, we need to know everything about his plans in hours, if not minutes. His arrest might provoke his associates – uninterested in their own survival – to accelerate their atrocity. If MI5 needs another £100m to ensure that captured information is analysed as fast as possible, no money could be better spent.

Forty-two days has a further hazard. Those who have worked to deadlines – that includes every journalist – understand the consequences of long ones. The edge goes off the urgency. Anyone who believes that today's policemen are so adamantine in devotion to duty that this could never apply to them should be working as Sir Ian Blair's spokesman.

At present, it is possible for the police to arrest a terrorist suspect, hold him for 28 days, charge him with a lesser offence, ensure that he is denied bail - and continue to investigate him. That is enough, and there is a further point. If all the experts in counter-terrorism were assuring us that the Government was right, one would defer to their judgement. But there appears to be little enthusiasm for this measure even among those whose lifetime's experiences in protecting the country have surely emancipated them from naive libertarianism.

So why is the Government pressing ahead? For the lowest of reasons, as advocated by the worst of Home Secretaries. The Spectator magazine has recently taken up pygmy-ology, the study of Labour ministers who might succeed Gordon Brown. In pursuit of this, it interviewed Jacqui Smith, the Home Secretary. One might have thought that she would have tried to rise to the level of events, dignifying a grave matter with weighty arguments. Not a bit of it: she sounded like a junior member of the Whips' Office, solely interested in the machinations of arm-twisting and vote-getting. Her shallowness was only rivalled by her interviewer's sycophancy. At one stage, he puts words in her mouth, to which she is happy to assent, describing Peter Goldsmith, Tony Blair's final Attorney-General, as a "tosser".

If our Home Secretary wants to be taken seriously, this is no way to talk about Attorneys-General. To be fair to Jacqui Smith, there is no evidence that she does want to be taken seriously or even knows what the word means. At the recent Police Federation Conference, she was given a rough time over misdemeanours in her student days. The coppers were missing the point. It does not matter that she was a silly undergraduate. It does matter that she still is.

The Government introduced 42 days in the hope of making the Tories seem weak on terror. Ministers are now assuring potential Labour rebels that they need not vote with their conscience, because the House of Lords is bound to reject the new powers. In other words, Labour is happy to see this supposedly vital proposal stifled, as long as David Cameron cannot revel in their defeat. Any government which can approach national security questions in such a frivolous and cynical spirit has lost all contact with morality, and that is Gordon Brown's fault, even more than Jacqui Smith's.