There is an issue about the discrimination provisions because the Qur'an does say that women should have half the share of men. Again, in the seventh century perhaps that kind of made sense, but in the twenty-first it very often doesn't. But in the arbitration contract that won't arise. An inheritance dispute might arise after someone dies but the two sides have to come together consensually.

There's crucial distinction that has to be drawn between the Shari'a, which is this hugely expansive vision of cosmic order that I've been describing, and principles of Islamic law, known in Arabic as "Fiqh" - a word that means understanding. If you're a devout Muslim, you don't argue against the Shari'a; the Shari'a is the path that God has laid down. But what you can do, and what people are doing all the time, is arguing over the correct interpretation of the Shari'a, arguing over the Fiqh. That's something that has been going on throughout Islamic history.

I spoke to my father - my father's from Pakistan and he's also a lawyer - I said to him, "Well what does the Shari'a say?" And he said, "Well, of course it doesn't justify suicide bombs," but he didn't seem to know where the Shari'a came from or what it was all about. The more I asked people in my family as well as friends, the more I realized that there seemed to be widespread ignorance in the Muslim community. And that's something which I actually found to be the case over the next two and a half, three years I spent writing the book.

There were periods in Islamic history when things like apostasy and blasphemy were made punishable. So you know it kind of depends - there's no argument, quite apart from the question of the divine or otherwise nature of the Qur'an, that huge swathes of Islamic law are man-made. Clerics here - in maintaining their power, will often try to elide that and say "Well no, actually this isn't man-made at all. Stoning is part of the divine revelation." It isn't in the Qur'an but the way this has been done over the years is to take the Hadith.

The one fatwa that everyone here is probably familiar with is the Salman Rushdie fatwa, but a fatwa doesn't have to be a violent thing at all. A fatwa is simply a ruling on Islamic law; there can be fatwas on clothing.

My background is such that I am uneasy about religious laws, I think there's always a real danger when you start appealing to a higher authority. It's self-righteousness, it's not righteousness, it's self-righteousness that takes control. But I think that it's absolutely crucial that that's not confused with the debate that takes place over Shari'a law in Great Britain at the moment. Because as far as anybody is concerned, when you talk about Shari'a courts now you're talking about - I don't know what people think.

The first rules about Islamic law weren't even written down for a century and a half after the Prophet's death, and it was another five centuries, half a millennium, before they assumed anything like a definitive form. So there have always been huge arguments over what Islamic law actually requires. There are four main schools of law in Sunni thought and there's a separate school of law in Shia thought, so these arguments do take place.