It's a principle, nothing else The things people call it, or the things they derive from it is a second thing. But it's not to say that that is the thing that will be the case.

For instance a private DEFENSE company may be something that follows but it's not a given. It could just as well be a neighbourhood watch or a defense organization with volunteers, or maybe someone says; I defend myself.
Or I defend my family.

Again it's a principle not a system,not a fixed code, not a human protocol, I've seen some people think of it like a constitution, or someone who wants to make a contract and let everybody sign it. Some think it's a law that needs to be implemented. It's a principle nothing else.