The military intervention in Libya by the United States and NATO offers new evidence that the just war theory stands in need of rethinking. The theory is fine as far as it goes. The problem is it doesn’t go far enough.
 
People who say the just war theory should be scrapped because modern warfare makes it irrelevant miss the point. Even nuclear war is unthinkable, though not thereby impossible, precisely in light of just war principles like proportionality (the force used should be reasonable in light of the military goal) and discrimination (don’t kill noncombatants by using indiscriminate force).
 
But military conflicts like the one in Libya do raise questions that classical just war theory simply did not envisage. Some of the current confusion over the rationale and goals of the intervention may reflect that fact. Hence the need for fresh thinking aimed at developing the theory.
 
For example: the typical case assumed by just war analysis is one in which a nation is weighing whether to take up arms to defend itself against what it regards as unjust aggression. Here principles come into play like just cause, competent authority, efforts to resolve the situation peacefully, right intention, reasonable probability of success, and good results proportionate to the harm the use of force will bring about.
 
The basic question raised by Libya comes, of course, right at the start. Moammar Gadhafi was not attacking or threatening to attack the United States or its allies. Instead the Libyan tyrant was in the process of gunning down Libyans who’d had the temerity to rise up in protest against his tyrannical regime. Thus the grounds for intervention were said to be humanitarian: preventing the slaughter of Libyan civilians.
 
Many Americans respond favorably to this rationale, and very likely with good reason. Without much tweaking of the principle, military intervention to protect innocent people from being massacred can well be seen as covered by the just war principle of resisting unjust aggression. But that only points to further questions. Here are a few.
 
Should humanitarian intervention go beyond halting the violence and extend to regime change—toppling the tyrant? There seems to be no agreement on that at the upper levels of the American government, much less within the NATO coalition. And if the correct answer is sometimes but not always, the question then becomes: when? 
 
Even an authoritarian government has a right, and sometimes a duty, to use force when necessary to maintain or restore public order. But when does this use of force become unjust and merit outside intervention? Should the United States be prepared to intervene in a civil war on behalf of the side it favors? If so, when and under what conditions?
 
Most people would agree that, generally speaking, intervention should first of all take the form of steps like sanctions and blockades, with direct military action employed only when and if it becomes necessary. But clearly there are exceptions—times when military action must come first. What are they? 
 
Just war thinking requires that the decision to go to war be taken by the competent authority. But who is that today?

In Libya, America and its allies took the precaution of getting a green light from the U.N. Security Council. Is that step always necessary now, or should it sometimes be set aside in the interests of greater goods? And for the White House to ponder: Isn’t it in the spirit if not the letter of the Constitution to consult Congress before the shooting starts?