Because bourgeoisie law does three things. Firstly it protects capital against individuals. Secondly it protects itself against individuals so it can maintain "order". Finally, it prevents capital against itself, to prevent it devouring itself in competition or sucking hard enough to create a revolutionary populace. Protecting individuals against each other or against capital is not the purpose of law enforcement, much less protecting people from war criminals. (Btw if anyone can find the parenti lecture this was based off, please tell me because i forget)