In my opinion Punishment should be determined by the laws the players/npc in power set. Some places will have relaxed laws, other places will have strict laws. I do not believe the punishment of murder should be be a one size fits all by the developer. Be that short//long spark loss, actual imprisonment, execution, the seizure of property in compensation, etc. By allowing the people in power be that players/npc to make the choices of what laws are laws, what the punishment for those laws are, etc allows people more options to settle in areas they agree with the laws those have set.
On a side note. I do believe their should be a sort of on screen indicator of the Kingdom, Duchies, County, Settlement you are in. Each with a list of Laws enacted. This way when traveling all you have to do is look at the tab, review the laws before proceeding to either follow or disregard the law. This way there is no argument of not knowing what laws are on the book in any given area.
Plenty of people will have many different opinions on laws in terms of government from far left, to far right on the traditional spectrum and those people should have the ability (regardless of my personal opinion) to enact whatever type laws they want. Be that just or unjust laws, as many people will determine if the law is just or unjust by their own personal opinion.
If you know a certain law is over zealous in a certain area. You many look at it as a deterrent to not break that law or you may look at it as if I do the alleged crime I may want to make sure I do not get apprehended because the punishment is to harsh.