Neither Warfare nor Justice
What shall we call the bin Laden slaying? For it seems to be neither warfare nor justice.
One of my friends called it "expediency", which sounds about right, and it fits Barack Obama to a T. Or you could euphemize it as "irregular warfare".
Another of my friends said "he needed killing." This too sounds about right, and it fits Osama bin Laden to a T. Or you could euphemize it as "justified homicide".
So what you call Obama's killing of Osama depends on if you have Obama or Osama in mind. This sort of semantic relativity is what to expect from a boundary case. My first friend took the Superego's point of view, my second friend took the Id's.
Bin Laden's gang of theocratic nihilists spread terror in the Middle East, much more than they ever did in the States. So call it frontier justice or irregular warfare or imperialist hubris or karma, bin Laden was targeted for assassination.
(And by the way, that wife was amazing. She approached a Navy SEAL on an assassination mission! Wow. Loyal indeed.)
Capturing bin Laden would have been better, from a constitutional point of view, and also better symbolically to treat him as criminal rather than warrior or martyr; but perhaps this is too subtle a point to be worth the risk and cost. As is, what we got was too brutal, and sets a bad precedent; but it ended his menace conclusively, and it gave primal satisfaction to some, and warning to others.
I see no fully satisfactory solution, given that is this is a boundary case, between crime and war. Terrorists are too big to be criminals, with rights, and too small to be heads of state, with privileges; so they lack protection. The real crime of the terrorist is that merely by existing, the terrorist reveals the continuity between crime and war.
Bin Laden's assassination is part of the USA's psycho-historically irreversible transition from Competent Empire (because successfully disguised as a Republic) to Incompetent Empire (because unmasked, even to itself). Next ahead; 90% chance of Incompetent Republic within my lifetime, and a 50% chance of Competent Republic within my daughter Hannah's lifetime.