My campaign features a series of city states which supplement their income (and influence and military might) by selling letters of marque, in effect licencing mercenary (and adventuring) companies.
Well, a Letter of Marque allows someone to attack an enemy of the State, right?
What I was thinking about would be the rules that govern small local mercenary groups; the kind that might hire out 5 men to guard a rich merchants house. The State doesnt much care about this sort of thing, there are no national enemies involved. But they do want to see Law preserved.
I initially thought that the city wouldnt have any particular laws governing mercenary groups, but as soon as the killing started, I realized that standard english-system "murder" rules dont really apply.
Imagine this situation: two merchants get into a trade war and their mercenary groups end up facing off in the street. Who is responsible for the ensuing bloodbath from a legal point of view? The individual soldier who slew another? The captain of the mercenary group? The merchant who gave the order to attack?