The row about Abu Qatada's extradition raises the question: what exactly is the function of the law?

We could regard it as a set of prohibitions, which is why so many people want the Home Secretary to follow due process. But there is another way of thinking about the law - to see it as merely a price list. So life in prison is the price we pay for murder, 10 years for armed robbery and so on.

This economistic conception of the law, embodied in the title of Gneezy and Rustichini's paper (pdf), 'A fine is a price' - is inspired by Gary Becker:

I began to think about crime in the 1960s after driving to Columbia University for an oral examination of a student in economic theory. I was late and had to decide quickly whether to put the car in a parking lot or risk getting a ticket for parking illegally on the street. I calculated the likelihood of getting a ticket, the size of the penalty, and the cost of putting the car in a lot. I decided it paid to take the risk and park on the street.

One could regard the decision on whether to deport Abu Qatada in the same way. Rather than ask: 'is it legal?' the Home Secretary should follow Becker and weigh the costs of (possibly) breaking the law against the benefits of doing so.

And here's the thing. This cost could be small. Worse violations of rights than in Mr Qatada's case have elicited only smallish fines - 'just satisfaction' - upon governments, for example:

- being raped by policemen. Fine '23,000.

- being 'systematically beaten and tortured, at least six times, with electricity'. Fine '21,825.

- being 'beaten, blindfolded, stripped naked, hosed with water and subjected to falaka (beating on the soles of the feet)'. Fine '43,000.

Those are for violations of article 3 of the ECHR, prohibiting torture - which you'd think would carry especially heavy penalties. Violations of article 6 (the right to a fair trial - the one relevant to the Qatada case) - have yielded smaller fines.

This poses the question. Given such low costs, why not simply deport Mr Qatada, have a whipround and pay the fine?

I don't think it is the case that the costs are in fact greater; it has been suggested that non-compliance with rulings might led to suspension from the Council of Europe, which some think a bad thing. Breaking a law and paying the price to do so is, in one sense, complying with the law; refusing to pay the fine would be non-compliance.

I suspect the answer is that this issue is not merely a matter of solving a problem; that could be done by bundling Mr Qatada onto the next plane to Jordan. Instead, it is about politicians' desire to reveal themselves as particular types of characters. They want to appear like upright law-abiding citizens rather than as Beckerian economistic calculators. Sometimes, though - and not just in this case - this preference can be a positive obstacle to problem-solving.