Just war theory can be meaningfully divided into three parts. These parts are: 1) jus ad bellum, which concerns the justice of resorting to war in the first place; 2) jus in bello, which concerns the justice of conduct within war, after it has begun; and 3) jus post bellum, which concerns the justice of peace agreements and the termination phase of war.
The rules of the first, jus ad bellum, are addressed, first and foremost, to heads of state. Since political leaders are the ones who inaugurate wars, setting their armed forces in motion, they are to be held accountable to jus ad bellum principles. If they fail in that responsibility, then they commit war crimes. In the language of the Nuremberg prosecutors, aggressive leaders who launch unjust wars commit “crimes against peace.” What constitutes a just or unjust resort to armed force is disclosed to us by the rules of jus ad bellum. Just war theory contends that, for any resort to war to be justified, a political community, or state, must fulfill each and every one of the following six requirements:
1. Just Cause
2. Right Intention
3. Proper Authority and Public Declaration
4. Last Resort
5. Probability of Success
6. Proportionality
Just war theory insists all six criteria must each be fulfilled for a particular declaration of war to be justified: it's all or no justification, so to speak. Just war theory is thus quite demanding, as of course it should be, given the gravity of its subject matter. It is important to note that the first three of these six rules are what we might call deontological requirements, otherwise known as duty-based requirements or first-principle requirements. For a war to be just, some core duty must be violated: in this case, the duty not to commit aggression. A war in punishment of this violated duty must itself respect further duties: it must be appropriately motivated, and must be publicly declared by (only) the proper authority for doing so. The next three requirements are consequentialist: given that these first principle requirements have been met, we must also consider the expected consequences of launching a war. Thus, just war theory attempts to provide a common sensical combination of both deontology and consequentialism as applied to the issue of war.
Osama bin Laden failed to meet -- defiantly so, the requirements of Just War Theory.
Orend, Brian, "War", The Stanford Encyclopedia of Philosophy (Fall 2008 Edition), Edward N. Zalta (ed.),
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http://plato.stanford.edu/archives/fall2008/entries/war/>.