Civs should have their own set of laws that special, and on more then one level of offence. You should be able to look up the laws of a certain Civ and make sure what your doing isn't illegal. There would be 4 levels of offence-
1. Minor - A simple crime, you won't get punished serverly, but the most you could get is a few days in jail... (Ex. Pickpocketing, fist fights, jaywalking, ect.)
2. Standard - A basic crime that pretty illegal, but not enought for the death sentence. (E.x. Tresspasing, stealing, Beating on someone, ect)
3. Major - Now things are getting interesting! At this point the guards will attack you, but they won't "try" to kill you. (E.x. Killing, arson, treson, rape, ect)
4. Extreme - Your going to jail for a long time, if they don't kill you first! Guards WILL try to kill you, but if you surrender, expect a long time in jail, if your lucky! (E.x. Assaination of important figure, destuction of important religous artifact, razing a town, ect)
Note that most of the crimes listed in the examples won't always be in that catagory, but they will be somewhere around that catagory (may need some extra programing however, becuase then we will have civs where "Killing = minor crime"). Also some places may have things legal where other places don't. Having done a crime major or higher in one civ and then escaping to another place will make you have "convict" status. In which civs who like the civ you came from or civs who live next to that civ will search for you. After a while (time depending on crime) your convict status will wear off.
What do you think?