Various authors of different nationality and different professional backgrounds – a political scientist, diplomat, lawyer, historian and philosopher – all internationally recognized in their specific domain, attempt to find an answer to this question in this book. They discuss whether the Judeo-Christian doctrine of the just war is still valid today. They attempt to draw often contrasting conclusions from the interventions in Kosovo and Iraq. They debate counter-terrorism and wonder whether it should be recognized as war. They examine the ambiguous role of the UN and of international legal system. Finally, they pose the question of international legitimacy and the norms which govern it at the most general level. They call for code of ethics, a policy and provisional institutions in a time of crisis, a time when power without authority and authority without power abound.