There was a glorious story in an Australian-owned tabloid about two teachers meeting in Queensland, where brothels have just been legalised. One of them had gone as a customer; the other was working there in her spare time.

I don't know how the story got out. The woman was "counselled", but could not be sacked, and neither could the man. The anti-discrimination commissioner has announced that it would be illegal if either of them were to be sacked for engaging in sexual activity which is perfectly legal in itself. This seems to me to miss some important points about teaching, and the difficulties of maintaining classroom discipline if one's hobbies are unusual.

Anyway, I was thinking about the moral issues involved, for a worm's eye column, and realised that there are two grounds on which legalised prostitution can be defended. In a slave-owning society, or even on where women have no rights, then it is none of the state's business what happens to a slave. In a free society, individual consenting adults may into transactions with each other, and that's none of the state's business either.

The trouble with prostitution in modern societies is that as a matter fact it involves both free and slave labour. I have no idea whether Belle du Jour was real, but I'm pretty certain Tracy Quan was. Both of them qualify as free agents. There must be others like them. Somehow this makes the slavery aspects even worse.

It still seems entirely wrong that only one side of the deal should be criminalised, but whether both or neither should be is less clear. What's obvious when you think about it, though, is that slavery should be treated as murder, punished with mandatory life imprisonment, and investigated with as many resources as a murder is.