Here is an excerpt from the Wealth of Nations on greed and self-interest (in the story of the butcher, baker, and beggar). And here is a piece on the economics of crime (and how judges' incentives matter). An excerpt:

Steven Landsburg, an economist at the University of Rochester, has suggested one way of doing that. A judge would get a fat bonus for every suspect he released, and a stiff financial penalty if the suspect machinegunned anyone. The fatter the bonus, the more the judge will want to risk releasing subjects, and the more the system will favour liberty over public safety. Whether the bonus is small or large, however, the judge has a strong financial incentive to think carefully about which suspects are worth the risk to society - and his bank account.

But what Professor Landsburg may not have realised is that his wacky-sounding idea is already used in most states in America, albeit in a disguised form.