There's a fairly active debate around the world about whether regulation should be more rules-based, as it is, for example, in the United States, or whether it should be more principles-based as, for example, the FSA, the Financial Services Authority in the United Kingdom, has pushed for. Now even under a principles-based system, you still need some rules. So I wouldn't want to make an overly stark comparison.
But I think the idea of a more principles-based system is that in a world where markets are evolving rapidly and the situation can change over time, it may be difficult to keep detailed rules up-to-date, whereas a more principles-based system—for example, with general principles around disclosure, as opposed to having detailed line-by-line rules—puts some responsibility on the industry players that they have certain principles they should have to live up to.