There is a great book that you might want to read, which gets at the thought process at the individual level. It's about a cop who stood up to corruption in his

There is a great book that you might want to read, which gets at the thought process at the individual level. It's about a cop who stood up to corruption in his precinct. The movie is good too: http://en.wikipedia.org/wiki/Serpico http://en.wikipedia.org/wiki/Serpico I'm sure there are lots of reasons, but idealistic people like this must be one of the factors.