The Corse are not so much Unlawful as Semi-Unlawful. They are like modern day Mafias. Sure, they are known to do tons and tons of illegal actions and are watched closely, But they do said actions secretly most of the time. You -can- see a mafia member stroll down the street without 5 cops trying to arrest him/her simply because he hasn't been caught doing anything wrong. Same case here.
