Whether States, coalitions of States or inter-governmental organizations can engage in humanitarian intervention lawfully without the UN Security Councils authorization has been debated at length. Following NATOs intervention in Kosovo in 1999, the international lawgiver had to act. The result was the concept of the responsibility to protect. But the fundamental question of the legality of humanitarian intervention remained. This book takes a new approach by combining legal theory and international law. Legal theory enables the concept of legal validity to be better understood and permits the...