This book examines the legality of the use of force by states against individuals and non-state groups located beyond its borders, in light of applicable international law. The issues discussed include force used in the 'war on terror', pre-emptive self defence, and targeted killings of individuals.

Provides a multi-perspective study of the international law on self-defence against non-State actors.

Since the adoption of the UN Charter in 1945, the use of cross-border force has been frequent. This volume invites a range of experts to examine over sixty conflicts, from military interventions to targeted killings and hostage rescue operations, and to ask how powerful precedent can be in determining hostile encounters in international law.

This is the first book to explore the concept of 'Grotian Moments'. Named for Hugo Grotius, whose masterpiece De jure belli ac pacis helped marshal in the modern system of international law, Grotian Moments are transformative developments that generate the unique conditions for accelerated formation of customary international law. In periods of fundamental change, whether by technological advances, the commission of new forms of crimes against humanity, or the development of new means of warfare or terrorism, customary international law may form much more rapidly and with less state practice than is normally the case to keep up with the pace of developments. The book examines the historic underpinnings of the Grotian Moment concept, provides a theoretical framework for testing its existence and application, and analyzes six case studies of potential Grotian Moments: Nuremberg, the continental shelf, space law, the Yugoslavia Tribunal's Tadic decision, the 1999 NATO intervention in Serbia and the 9/11 terrorist attacks.

This book comprises contributions by leading experts in the field of international humanitarian law on the subject of the categorisation or classification of armed conflict. It is divided into two sections: the first aims to provide the reader with a sound understanding of the legal questions surrounding the classification of hostilities and its consequences; the second includes ten case studies that examine practice in respect of classification. Understanding how classification operates in theory and practice is a precursor to identifying the relevant rules that govern parties to hostilities. With changing forms of armed conflict which may involve multi-national operations, transnational armed groups and organized criminal gangs, the need for clarity of the law is all-important. The case studies selected for analysis are Northern Ireland, DRC, Colombia, Afghanistan (from 2001), Gaza, South Ossetia, Iraq (from 2003), Lebanon (2006), the so-called war against Al-Qaeda, and future trends. The studies explore the legal consequences of classification particularly in respect of the use of force, detention in armed conflict, and the relationship between human rights law and international humanitarian law. The practice identified in the case studies allows the final chapter to draw conclusions as to the state of the law on classification.

States invariably justify using force extraterritorially by reference to their right of self-defence. In doing so, they accept that the exercise of this right is conditioned by the customary international law requirements of necessity and proportionality. However, these requirements are notorious for being normatively indeterminate and operationally complex. As a breach of either requirement renders ostensibly defensive action unlawful, increased determinacy regarding their scope and substance is crucial to how international law constrains military force. This book examines the conceptual meaning, content, and practical application of necessity and proportionality as they relate to the right of self-defence following the adoption of the UN Charter in 1945. It provides a coherent and up-to-date description of the applicable contemporary international law and proposes an analytical framework to guide its operation and appraisal. This book argues that necessity and proportionality are conceptually distinct and must be applied in the foregoing order to avoid an insufficient 'catch-all' description of legality or illegality. Necessity determines whether defensive force may be used to respond to an armed attack and where it must be directed. Proportionality governs how much total force is permissible and prohibits excessive responses. Both requirements are shown to apply on an ongoing basis throughout the duration of an armed conflict prompted by self-defence. Compliance with necessity and proportionality ensures that the purposes of self-defence are met, and nothing more, and that defensive force is not unduly disruptive to third party interests and to international peace and security.

In NATO Rules of Engagement, Camilla Guldahl Cooper offers clarity on a topic prone to confusion and misunderstanding. NATO rules of engagement (ROE) are of considerable political, strategic and operational importance, yet many of its concepts lack clarity. The resulting ambiguity may be detrimental for people involved and for mission accomplishment. Through a thorough analysis of the concept, purpose, development and use of NATO ROE, Cooper contributes to improved understanding and implementation of NATO ROE. The book covers all use of force categories and relevant law relating to the use of force during armed conflicts, including the complex concepts of hostile act and hostile intent, direct participation in hostilities, and the increasing reliance on self-defence during armed conflict.