The authorities and their opponents are fighting a phoney war over anti-terror laws, in which liberty is already the loser.

Our elected leaders are once more doffing their caps to a man in a police helmet. Gordon Brown and his ministers have indicated they will support extending the time limit for detention without charge beyond 28 days. Two weeks ago Sir Ian Blair, the Metropolitan Police chief, gave the Government its cue by demanding powers to hold suspects for at least 50 days. In how many cases had police found 28 days inadequate? Sir Ian admitted that the total is – none. Since the limit was extended to 28 days in 2005, only 11 people have been held for longer than 14 days, and eight of them were charged.

So is the proposed change in the law designed to get the other three blokes?

No, said Sir Ian, the point is that “at some time in the future 28 days is not going to be sufficient. If you can see an epidemic moving towards you, you take precautions before it arrives.” He raised the spectre of the summer’s failed car bombings to support his call. Presumably security reasons forbade him from explaining exactly how a 50-day detention would have prevented those surprise attacks.

The only “epidemic” in evidence is one of fear, being spread by officials via worst-case “what if?” scenarios. The panicky Government grabs at new anti-terror laws like a security blanket to give it a sense of being in control. Mr Brown made clear that he supported longer detention limits even before he became Prime Minister. Not at all like that nasty Mr Bair, is he?

Two years ago the civil liberties lobby claimed victory when MPs rejected Mr Blair’s plans for 90-day detention and voted “only” for a 28-day limit. Now the Government’s opponents talk as if defending 28 days is the height of civil liberties in Britain. But if the possibility of being locked up for four weeks without charge is the definition of a free society, then the right of habeas corpus is already a corpse.

Worse, these opponents can seem as guilty of fear-mongering as the Government, as they speculate about how longer detentions will spark more terror attacks by alienating Muslims. Shami Chakrabarti, of Liberty, even concedes that the limit could be extended if policing was brought to a “standstill” by multiple terror plots. A whiff of fear emanates from all sides. And as experience should teach us, that invites further attacks from the parasitic forces of terror that feed off our insecurities.

Benjamin Franklin suggested that “those who would give up essential liberty to purchase a little temporary safety deserve neither liberty nor safety”. In which case, those fighting a phoney war over whether it should be 28, 50, 90 or 500 days look likely to get exactly what they deserve.

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