Collective Self-Defence in International Law

Collective self-defence can be defined as the use of military force by one or more states to aid another state that is an innocent victim of armed attack. However, it is a legal justification that is open to abuse and its exercise risks escalating conflict. Recent years have seen an unprecedented increase in the number of collective self-defence claims. It has been the main basis for US-led action in Syria (2014-) and was advanced by Russia in relation to its full-scale invasion of Ukraine (2022-). Yet there still has been little analysis of collective self-defence in international law. This book crucially progresses the debate on various fundamental and under-explored questions about the conceptual nature of collective self-defence and the requirements for its operation. Green provides the most detailed and extensive account of collective self-defence to date, at a time when it is being invoked more than ever before.

Provides the most detailed and extensive account of collective self-defence at a time when it is being invoked by states more than ever
Employs a methodology focused heavily on analysis where conclusions are grounded in an extensive study rather than being purely rooted in legal theory
Reaches new conclusions regarding the legal status and requirement for collective self-defence