Crime & Punishment

Each settlement or kingdom has its own sets of laws and its own methods of law enforcement and justice.
Characters who break local laws and are caught will gain notoriety and possibly trigger law enforcement action. A score of 1-3 is limited to the area of the crime and only relevant within that area, achieving a score of 4-5 will mean you are wanted regionally, a score of 6 will make you an enemy of the entire kingdom you are in. A score of 7-8 will make you an enemy of all kingdoms on the continent. A score of 9-10 will make you an enemy of the entire positive plane and all of its denizens.
When a character goes to jail, they roll a d20 with no modifiers, if the result is 16-20, they will get to play in character that session, interact with their surroundings, and potentially seek freedom. If the result is 1-15, the character will remain in prison and the player will be either be provided with a party follower, NPC or a new character to play for that session. At the start of each session, for the duration of the prison term, the character may roll a d20 again for a chance to play as their main character. While in prison the character does not receive any experience and any loot found by the player whilst using a back up character will remain with that character (not to be transferred back to the player's main character upon their release). 
There are 4 levels of notoriety which are determined by the amount of notoriety points each character has;
1-2 points - Troublemaker Unlike lawbreakers or criminals, being a known troublemaker is more about reputation than restitution. As such it can be hard to lower the score without actively working to improve that image or letting time pass. Score will reduce by 1 point for every six months that go past without incident.
Guards are likely to keep a close eye on you and you will be on the list of suspects for any crimes committed in the area.

3-4 points - Lawbreaker Being known as a lawbreaker can have unfortunate side effects but it is not an iredeemable condition. Paying fines 150-500gp, serving weeks in prison, repairing damage, turning oneself in or even finding the right connection can reduce the score.
There is a good chance there is warrant out for your arrest, the further you are from the site of the crime the less likely that is. A competent disguise and a low profile is usually enough to get by without notice. Once recognised however law enforcement will consider it a priority to apprehend you and have you stand trial. 
Lawbreakers are wanted alive by local or regional law enforcement.

5-6 points - Criminal Having passed the point of hard return reducing notoriety at this level requires either serving years in prison, clear their name, or gain a pardon from a powerful party.
The hammer comes down when you are considered a criminal, wanted posters are hung in public and your description is circulated. Your places of resort and associates are being watched carefully. Rewards for your capture are signficant and when someone comes after you they will do it in force. Worse still your associates, friends and family are often heavily scrutinised or harrassed
Criminals may be regionally wanted alive (5) or nationally wanted dead or alive (6).

7+ points - Enemy of the State
Only possible ways to expunge this level of notoriety is a full royal pardon, divine intervention or a display of utterly epic heroism. Even then some crimes may never be forgiven.
Each character's level of notoriety will impact their public perception, law enforcement, punishments and methods to reduce their score.
At this point, soldiers and guards have memorised your details, there are dedicated teams of agents tracking you, authorities will coordinate efforts and information and unless granting asylum, they will extradite you to the region your score is highest. Famous adventurers and bounty hunters seek to make a fortune from your death or capture. Your disguises and deceptions must be masterful and if you show the slightest amount of resistance, pursuers will not hesitate to kill.
Enemies of the State are wanted dead or alive.