Moral justification for the execution of criminals of war?

[bennyboy]

People may also feel a certain way about it.  They may desperately want to kill that person.  Unfortunately, the "no killing" rule doesn't state "unless you really wanna"...and so, while a person may understand that it's a good rule for society..they also understand they may find themselves personally unsatisfied by it.    

I can't imprison you, either. I have to petition the government to do it on my behalf.
Nor can I take your property at a whim. If I think I'm owed, I have to petition the government to do it.

If I desperately want to kill a person-- well, I might just do it, knowing the legal consequences, and I wouldn't consider it immoral. But generally speaking, I'd have to petition the government to do something like that, since I cannot legally do it myself.