Here's a link to an article that may not be the final word, but it looks like an essential place to start. It's an interview with David Scheffer,
the Mayer Brown/Robert A. Helman Professor of Law Director, Center for International Human Rights, at Northwestern University School of Law.
Scheffer, the U.S. Ambassador at Large for War Crimes Issues from 1997 to 2001, is author of the forthcoming book, "All the Missing Souls: A Personal
History of the War Crimes Tribunals." (Princeton University Press.) He teaches international human rights law, international criminal law, and
corporate compliance and the social mandate.
He discusses the attack on Osama Bin Laden, but I suppose the analysis could apply to any other "terrorist."
inthearena.blogs.cnn.com...
rimes-issues-weighs-in/
Whether the United States violated international law in the killing of Osama bin Laden depends not only on how one defines what has been going on
since September 11, 2001, but also how this particular operation was carried out on Pakistani territory.
The popular and patriotic narrative is that the United States is at war with Al Qaeda; Osama bin Laden commands Al Qaeda; thus under the law of war
bin Laden is a legitimate target for a lethal assault regardless of his personal situation (armed or unarmed, awake or sleeping) at any particular
time.
The more complicated view is that bin Laden is under federal indictment for terrorist attacks against U.S. civilians and government personnel on U.S.
territory and at diplomatic and military targets in various parts of the world—attacks that violate federal antiterrorism law—and as a matter of
law enforcement should be captured and brought to trial, preferably before a federal criminal court in the United States.
Despite the certainty with which proponents of either view argue their respective policies, the fact is that the United States has been pursuing both
agendas for almost a decade: waging war and enforcing antiterrorism law. The Afghan and Iraq wars and various military strikes in Pakistan and Yemen
testify to the logic of a war.