Easiest to understand would be crimes of passion. Someone who kills without pre-meditation is usually considered to have committed a lesser crime than someone w

Easiest to understand would be crimes of passion. Someone who kills without pre-meditation is usually considered to have committed a lesser crime than someone who planned it. Then you have more complex situations. Killing an intruder in your home for example. The details are crucial to understanding if it's justified or not. Even more complex are the rules of engagement in war. Was the bombing of Dresden justified, etc. Every society grades and judges violent acts in context.