One of the most constant presences in any campaign is the guard. They stand watch over the civilization and can define how many encounters and situations play out. For the GM, they can be a useful tool; a guard showing up at just the right moment can create a really fun scene. Conversely, the presence of crime can play similar roles. A crime-ridden city feels different from a heavily-policed one, and adding criminals to your story can create very engaging moments. So how do we define the variables--what are guards like, and what is crime like?
Answering those questions requires considering a number of factors. This guide will help you to address several ideas that will allow you to give questions of crime their best portrayal of your game. [You can read about my homebrew setting's situations with crime and punishment too.]