The British do like to ban things. It is one of our national vices.

And the things we often like to ban are what other people get up to. We tend to believe that our moral disgust or ideological certainty about what other people do converts easily into legal prohibitions. To ban something, we seem to assume, is to eliminate it. Writing out a new page in a statute book is seen as somehow having the same effect as casting a spell: if we use just the right form of words, and are sufficiently solemn in doing so, we believe we can change reality.

Political debates can thereby be limited to whether something "should be banned". Rarely addressed are the more important questions of whether something can be "banned" and what may be the unforeseen consequences of having a ban. These are seen as second order concerns. It does not seem to matter how or whether the ban will work in practice: the deplored activity must be prohibited. It shouldn't be allowed.

However, to "ban" something is not to eliminate it; it merely means that future incidents of it may be attended by different legal and other consequences than it otherwise would have.

There is no one explanation as to why the clamour to ban things has such a central role in our political discourse. One possible reason is that the progressive widening of the franchise, and the attendant development of our democratic culture, was in respect of control of the legislature, and not the executive directly. Politicians could gain support by promising to make laws rather than actually doing things: "vote for me and I can ban this for you". Another possible explanation is the latent Puritanism in our national culture has long mixed with that popular deference to the rule of law which EP Thompson traced back to the early 1700s: so when we do not like something, we instantly think of the law as the best way to stop it.

This is not a simple left/right issue. Both conservatives and radicals want to ban things: different things, of course, but the political reflex is very much the same. Only the topics vary: fox-hunting, smoking, abortions, pornography, sado-masochism, recreational drug use, and so on. Everyone seems to want to ban something which other people do.

And so the news last week that the government is again thinking of criminalising those who pay sex workers comes as no great surprise.

Indeed, it seems our government is again "looking to Sweden" in respect of how to deploy the criminal law in the context of sex work, as if invoking the name of a Scandinavian country is enough to cloak an illiberal and grubby initiative with the soft glow of freshly-fallen Nordic snow.

In fact, our domestic laws regarding sex work are a complete mess.

Their general effect is to marginalise sex workers socially and to surround them with those whose conduct is at instant risk of criminalization. This is neither sensible nor safe for the sex workers.

Threats of criminal convictions are more likely only to deter someone from detectable types of behaviour than to deter them from refraining from the deplored behaviour altogether.

Criminalization really needs to be taken out of sex work, unless there is evidence of trafficking. (And the purported evidence for widespread trafficking has been discredited by Nick Davies and Dr Belinda Brooks-Gordon amongst others).

A wiser approach to the law and policy of sex work was last week shown by a female Canadian judge, in a 132-page judgment which is both beautifully-written and a superb exercise in progressive jurisprudence.

Judge Susan Himel of the Ontario Superior Court of Justice struck down a range of prohibitions related to sex work policy. She came down on the side of the "right of prostitutes to express themselves in an effort to protect their personal safety". Furthermore, she notes "by increasing the risk of harm to street prostitutes, the [provision banning communications for the purposes of prostitution] is simply too high a price to pay for the alleviation of social nuisance".

This judgment of Judge Susan Himel is humane and refreshing. It applies the law in a liberal and proportionate way. It takes seriously the concerns and interests of sex workers. It is a judgment which should be read by every person with an interest in the topic. One only hopes it will not be appealed.

David Allen Green is a lawyer and writer. He was shortlisted for the George Orwell blogging prize in 2010. On 18 October 2010 he will be chairing a talk at Westminster Skeptics by Dr Belinda Brooks-Gordon (with a reply to be given by Dr Brooke Magnanti) on the Law and Policy of Sex Work.