Abstract: Considers the international law controversy provoked by the NATO campaign in Kosovo. The central question addressed is whether the constraints imposed by international law on the non-defensive use of force are adequate for the maintenance of peace and security. In response, considers the legality of NATO's forceful humanitarian intervention by reference to both jus ad bellum (recourse to war) and jus in bellum (lawfulness of conduct in war), and argues on behalf of legitimacy by way of an emergent framework of principled humanitarian intervention. A pre-legal proposal is made to move in the direction of establishing a legal doctrine of humanitarian intervention that balances the clams to protect peoples against the importance of restricting discretion to use force in international relations.

Keywords: humanitarian intervention, international law, jus ad bellum, jus in bellum, legitimacy, NATO, use of force,