Music documentaries are hard to tell, but I think they're an amazing vehicle to look at racism, our attitude to sex, the way we judge drugs. There's the ability to get a big audience because of these incredible, iconic, charismatic people. You can look at a number of issues - the challenge is to make sure you choose something that has all those issues. Popular music is like a mirror of culture, of who we are.

You know so many documentaries now are very carefully scripted before you start, and then people are sort of put in chairs which are beautifully lit, and they tell their stories and you do that with another 10 people and you then construct a story from what they say. You do a sort of paper thing, and then you put some images in-between, and that's your film. And that's so not what I think is a good documentary. It can be so much more than that, it should be much more of an adventure and much more uncertain... like real things are.

Cocaine and crack are essentially the same thing. Cocaine is a middle-class drug. Crack is a poor person's drug, which carries a felony conviction for possession. And once you get this felony conviction, which given that the whole community is pretty much strung out on it, you become basically sidelined into an alternative kind of lifestyle. You become completely marginalized. You can't get public housing, you can't get a lot of jobs, you can't vote. You have a real problem doing anything to get you out of the rut that you're in. You become basically a non - person.

I studied law before I became a filmmaker, and I actually have a great belief in the justice system and the rule of law. I think it's the thing that separates us from animals. I really believe in the rule of law because it's an attempt to bring rational accountability to human behavior, which has a great capability of becoming irrational.

I've spent a lot of time in L.A., it's always reminded me a bit of Jo'burg, which is a deeply segregated city. And L.A. is really like an apartheid city; white people just don't go to South Central. It's just a different world.

I think if people give you their time and they haven't got any money then they deserve to get something. Not so that you bribe them to say things that they wouldn't otherwise say.

For some reason, politically there's a distinction between cocaine and crack. Cocaine is not a felony conviction because it's used by middle class and wealthy people. Crack, which is used by people in South Central, carries a felony conviction.