But Just War theory is approached from a different perspective. It isn't as individually focused but is more socially focused. How should societies (re: nations) react to aggression, belligerence, human rights violations, etc. It's a bit more complicated when viewed on a grander scale.
So far I've read a very good (and thorough!) book by Michael Walzer, Just and Unjust Wars. It's quite a read, but by the end gives as good an overview as one could imagine. I've moved on to Love and Justice by Reinhold Niebuhr to focus on Just War arguments during WW2 and beyond. My initial thesis was that WW2 led to a revision of Just War theory making it easier to go to war. Because I believe WW2 to be an exception and not a rule, this would have made theory LESS just instead of MORE just. The jury is still out on it though.
A different course I may take is to look at what other concepts are necessary to arrive at a jus ad bellum and jus in bello. What are the sine quibus non for Just War that may not pop into our heads as easily as aggressor identification and combatant/non-combatant status?
Three points have popped out at me and will most likely form the basis for my paper.
1) A well trained military is needed for a just war. Not only in technical aspects such as aiming (good aim, after all, could be the difference between hitting a combatant or a child), but also moral training in all the points that Walzer brings up. Just War theory is inherently casuist in nature--rules are made only after the fact and are fluid. Yet studying the historical cases is what ethicists do and these inform decisions for new cases. A soldier in the field is often expected to make a moral decision in a matter of moments. This can't happen in a vacuum. Moral training is necessary as well as all the other military training.
2) An open, national conversation must take place. This is most obvious in the time leading up to war (jus ad bellum), but is also important if any of the means used in the conflict become controversial (jus in bello). The decision to go to war cannot be made solely by politicians or military leaders. The entire public must be included in the discussion. I also feel that voluntary enlistment is the only way to go. If the case can't be made convincingly enough to raise a military voluntarily, then the case for war may not be just.
3) An accurate and free press. The conversation above cannot take place if there is not a free and high quality press. Conversation is based on facts as well as feelings and faith. If the facts are wrong, the conclusion may be wrong. The most blatant (and recent) example of this is the current war in Iraq. If the conversation was based upon Saddam Hussein's possession of weapons of mass destruction and affiliations with Al Qaeda, then the conclusion could be ill-founded. If the conversation were based on truth, we may have arrived at a different decision.
There is a lot more to be said about all three of these, but that's why it'll be a 20 page paper.
Other books on my to-read list:
And a bunch of journal articles I haven't gotten to yet. . .