The decision by Gordon Brown's government to push through 42-day detention without charge was wrong on so many counts that it must rank as one of the worst of the many bad decisions taken since New Labour came to power. At 28 days the UK was already by a wide margin top of the league of established democracies in the length of pre-charge detention. No evidence has been provided that this further extension is needed for anti-terrorist investigations, or that those responsible for those investigations are calling for it. On the contrary, it is likely to further alienate the communities whose cooperation is most needed for preventing terrorist atrocities, as the history of detention without trial in Northern Ireland demonstrated.
The measure was only pushed through the Commons by massive arm-twisting of Labour MPs, playing on their fear that defeat would destroy Brown's remaining authority, and by the shabbiest of deals with the Democratic Unionists. And it has demonstrated the bankruptcy of the Blairite tactic of making up policy to wrong-foot the Tories, which has sunk Brown's credibility since the autumn.
David Davis's decision to resign his seat and fight a by-election on the issue was variously described as maverick, wrong-headed, self-indulgent and a waste of public money. It won support across the political spectrum, however, for two main reasons. The first is that it chimes in with a widespread feeling that our distinctive liberties are being eroded across the board, with Labour's restrictions on freedom of expression and assembly, the extension of mechanisms of surveillance, invasions of privacy, development of databases of all kinds, the plan for biometric ID cards and so on.
No doubt there are arguments to be made to support aspects of these developments. Jill Saward decided to stand against Davis on the platform 'The liberty to live without fear', especially women in fear of rape, and argued that the national DNA database and CCTV surveillance have provided essential tools in the fight against serious crime. Yet we should resist the extension of the DNA database to the whole population, as she has proposed, and demand much more effective safeguards to ensure that surveillance is not used for trivial or improper purposes.
Again, no threat to liberty may be entailed in the idea of identity cards as such, carrying basic personal information. I still have the identity card issued to me in the second world war, number LFZF 324/3, later transferred to my national health card. I carry such cards for identification in all kinds of situations - passport, driving licence, bus pass, European medical card and so on. What is wrong is trying to roll all these into one for administrative and personal convenience, and adding a whole lot of personal information, which no one can trust the government to gather correctly, to keep safe when gathered or not use for improper purposes.
So we need to get the balance right, and David Davis has tapped a widespread concern that the government has got the balance wrong, even though we may not agree with him on every detail.
A second concern that Davis has tapped into is the widespread distrust of parliamentarians and the political class as a whole. They are seen as unprincipled, more concerned with holding onto power and its personal benefits than doing what they believe to be right. The methods by which a Commons majority was achieved for the 42-days law epitomised these failings - and won support for Davis as someone prepared to sacrifice future cabinet office for a principle he believed in.
However, what Davis has not said, because as a Tory he is unable to do so, is that for the past 25 years parliament as an institution has proved a broken reed in defending the liberties of the subject in the face of executive encroachment. It was for this reason that the Labour government in 1997 found it necessary to introduce the Human Rights Act and give UK courts the power to enforce it against the executive and to caution parliament itself against potential legislative breaches.
The Tories have not been backward in accusing judges who do so of acting undemocratically, and have proposed to amend if not abolish the Human Rights Act. Yet the independence of the judiciary is an essential component of a democratic system, especially when it is defending the basic rights and freedoms necessary for citizens in a democratic society.
If Davis's action serves to strengthen the liberal tendency in a future Conservative administration, then it may have served a useful purpose. But don't hold your breath.
David Beetham is associate director, Democratic Audit