Gordon Brown's standing as a serious-minded and principled politician was thrown into some doubt by the fluffed opportunism seen in the abolition of the 10 per cent tax rate.
But his attempt to force through a counter-terrorism bill that would allow suspects to be held without charge for forty-two days represents a new and unprecedented nadir in his record.
It is a piece of unprincipled and pointless political symbolism, offensive to the central tenets of liberal democracy.
There are a number of arguments that can be made against the extension of detention without charge. Some of these arguments are addressed to the likely consequences of allowing 42-day detention. The simplest objection is that allowing 42 days detention without charge is simply unnecessary, and would do no good.
Ministers admit that there has not yet been a case where police claim that they needed more than the current 28 days in order to charge a subject. So the move to 42 days may well be completely useless in terms of promoting security.
And what of those who are not charged after over a month in police custody? Innocent people could face the Kafkaesque prospect of having their careers and lives ruined, even though they are never charged with a criminal offence.
As a further consequence, support for the police and the security services would only be undermined if lengthy detention without trial became commonplace. One can look at the experience of internment in Northern Ireland in the early 1970s to show that, as soon as the actions of the powers-that-be demonstrate contempt for due procedures, communities withdraw their support from the police.
With these concerns in mind, it is a curious fact that, in public debate on this issue, one often hears the claim that we have to "strike a balance" between liberty and security. Indeed, the metaphor of "striking a balance" has come to be an unquestioned dogma of much thinking about civil liberties and terrorism.
But more careful examination shows that this metaphor is deeply misleading. If reducing liberties through extending pre-charge detention does not help the police, ruins innocent lives, and alienates minority communities, then there is no corresponding gain in the purported balance of liberty against security. Instead of a balance, we have a loss of both liberty and security. Who would be in favour of that?
But the talk of "striking a balance" is misleading in more ways than just this one. We can deny that gains in one always create losses in the other. But, even in cases where a reduction in civil liberties did promote our security, we can still deny that we should think in terms of how best to balance them against each other.
Instead, we might think that certain liberties - like the freedom from detention without charge - are simply too fundamental to be traded-off against gains in our personal security. This is because personal security may itself only be truly worthwhile as long as these liberties are protected. It may do us no good to be kept safe from harm if it is at the cost of living in a country that is no longer a civilized liberal democracy.
Most importantly, it is a fundamental error to think that, in a democratic society, the central task of government is to keep us safe.
The life of free individuals in a democratic society is inherently risky. Good laws and good policing can reduce some of those risks, but only by a certain degree.
Criminals and terrorists can exploit the openness of a free society in order to cause us harm. But we have always known that this is so: it is simply the price we pay for living the way we live. Knowing that we live under unavoidable risk is no reason to sacrifice our way of life or to give up our fundamental freedoms.
In a discussion of the image of "balancing" liberty and security, the political philosopher Jeremy Waldron has raised a number of other problems with overly simple ways of thinking on these issues. For one, we shouldn't forget that, insofar as we care about our security to live our lives free from interference with our bodily integrity or freedom of movement, we should be concerned with our rights against over-zealous or misdirected policemen, and not only with our security from terrorists.
We should also bear in mind that, even when restrictions on liberty do bring gains in security, not all of those who benefit pay the price.
Even if extending detention without charge did bring gains in overall security, a very high price would be paid by any innocent individuals who found themselves at the sharp end of mistakes by the police. (And mistakes do happen: remember the 250 armed police who invaded the home of two innocent men, Mohammed Abdulkahar and Abul Koyair (shooting Abdulkahar in the process), at Forest Gate in June 2006.)
It is difficult to avoid the suspicion that Brown, as well as other Labour ministers, realize that the extension of detention without trial would be oppressive, illiberal and counter-productive. So why do they pursue this policy? Presumably because, in a haze of bad judgement and wishful thinking, Brown believes that this kind of empty symbolic politics can enhance his reputation for toughness, and play well to middle-England.
It is a cruel irony that doing the unprincipled thing on detention without trial is, contrary to Brown's belief, also very bad politics.
Brown allows the Tories to sound like the voice of civilized reason on this issue, while making his own party sound shabby, insincere and opportunistic. Hopefully there will be enough Labour MPs with sufficient self-respect to block this disgraceful surrender of political principle.
If the extension of detention without charge is defeated, one can only hope that Brown will draw a line under this sorry episode and move on.
He may discover that, as well as being the right thing to do, a return to a more principled politics could also start to lift the air of drift and dishonesty that has come to settle on his government.
If, on the other hand, the Bill passes in its current form, it will be a disastrous day for liberal democracy in this country.