Think of it as the dilemma of 24. In the TV thriller, hero Jack Bauer has 24 hours to avert a catastrophe - say, to prevent terrorists detonating a nuclear bomb over Los Angeles. Over the course of 24 hour-long episodes we urge Bauer, from the edge of our seats, to do whatever it takes to stop the killers. As we watch, our nerves taut, there is no ethical corner we don't want Bauer to cut, if that's what he has to do to prevent murder and mayhem. In one series, our man cuts off the head of a villain with a hacksaw - and we're glad he's done it.

That's fiction, but it seems a version of Jack Bauer syndrome operates in real life too. Almost three-quarters of us are happy to give up civil liberties in order to make us safer from terrorist attack, according to Monday's Guardian/ICM poll. Having seen the all-too-real threat of the July bombings, 73% are ready to pay the price, ready to let our protectors do whatever has to be done.

That will bring cheer to Tony Blair, whose parting words before he left for his Barbados holiday were a declaration that "the rules of the game are changing", accompanied by an aggressive 12-step programme for combating terror. Since then the government has been consulting on some of those steps and later this week, perhaps tomorrow, Charles Clarke will announce what action he plans. If our poll is right, and Jack Bauer syndrome really does apply, he will face little public resistance.

But perhaps he should. For the trouble with a 24 approach to policy-making is that it relies too heavily on the gut - and too little on the head.

Start with Blair's first step, the deportation of the small number of foreign nationals deemed to be fostering hatred or advocating political violence. Some of these "preachers of hate" - the men who praise the killers of 9/11 and 7/7 as "magnificent" - would be kicked out of the country, never to return. Good riddance, says the 24 viewer in each of us.

Then we think practically for a moment. Given that terrorism is a global business, are we that much safer if a hatemonger is moved abroad rather than here? Wouldn't it be better if he were out of circulation altogether and behind bars? Deportation simply relocates the problem; it does not solve it.

The principled objection centres on the nature of the countries in which these extremists would be dumped: Jordan, Egypt, Algeria, Morocco and Tunisia, places where the newly arrived expellee from Britain could expect to be greeted by the torturers of the local secret police. Who cares, says Bauer. Maybe a little pressure on the bad guys will get them to talk. But most of us, on reflection, do not really believe that. We draw the line somewhere - and that somewhere is state-sanctioned torture. Our own Human Rights Act bars us from sending anyone to face such a fate.

The government has got round that by asking receiving countries to sign "memoranda of understanding", promising to respect the human rights of any deportees. Clarke says we can rely on those promises just as we trust the US when it says it won't execute people it extradites from Britain. To see any difference between, say, Egypt and the US is, insists Clarke, "latter-day imperialism".

But Liberty, the human rights advocacy group, points out a key difference. The US admits it implements the death penalty; its policy is entirely in the open. None of the countries on Blair's list admits it practises torture; so what value is a commitment from a foreign government to refrain from doing something it denies in the first place?

Blair also wants action on homegrown "preachers of hate", those who cannot be deported. They will be put under control orders - facing curfews, wearing electronic tags, their use of telephones and the internet restricted and their right to meet others curbed. Given what some of these hardliners believe, my heart will hardly bleed if they now find it a bit harder to log on to killallwesterners.com.

But whether I sympathise with such people is not the issue. The trouble with control orders is that they are too harsh on the innocent and too soft on the guilty. For the former, they count as a form of punishment without trial. For the latter, a control order can only slow down a determined terrorist from doing his worst.

The solution is obvious. If the authorities suspect someone is involved with terrorism, that person should be prosecuted and jailed. Too tricky, says the government; we can't get the evidence. But if that's the problem, then we need to change the rules on what counts as admissible evidence - allowing wiretap transcripts, for example, as most other countries already do. If the suspect has not yet done anything wrong, but it's feared he might, then stalk his every move. Put him under 24-hour surveillance until we know what he's planning - and then charge him. But that costs big money, says the government. No problem, take the money out of the black hole that is identity cards.

The key point here, and it applies to almost all of Blair's 12-step programme, is that while these new plans might give us a brief, Bauer-style rush of blood, they are either misguided or unnecessary. If they're not wrong in principle, they're wrong practically, or where they're right, their objectives could be met just as well by laws we already have.

So Blair wants to crack down on those guilty of "justifying or glorifying terrorism". That will be tricky - unless he plans on prosecuting his wife for saying Palestinian suicide bombers had "no choice but" to kill Israeli civilians. Or perhaps he fancies the prospect of a show trial starring George Galloway. What Blair surely wants to get at is incitement to terrorist acts - and that's already against the law.

Blair's programme includes a ban on hardcore Islamist organisations such as Hizb-ut Tahrir and al-Muhajiroun. I oppose everything that these groups stand for - but I feel the same way about the BNP, and no one is calling for it to be banned. Democracy forces you to accept that even the most repulsive opinions have a right to be aired somewhere. Besides, what quicker way to turn these fringe extremists into heroes than by declaring them off limits?

Closing down mosques deemed hotbeds of extremism is similarly wrong-headed. That will alienate the very Muslim community whose cooperation the police and intelligence agencies need so badly. The sight of a dawn raid on a house of worship, police armed with padlocks, will confirm every lurid extremist claim about a state war on Islam. Again, anyone guilty of incitement can be charged under existing law.

Almost all of the Blair proposals are like that - superficially appealing, but on closer inspection either flawed or unnecessary. This is a minefield, one we all need to step through carefully. This is not TV, this is real life - and it's much more dangerous.

freedland@theguardian.com