This book provides a comprehensive analysis of collective self-defence in international law, a topic which the book's author claims has garnered limited attention. Indeed, previous scholarship on the broader topic, such as the Oxford Handbook on the Use of Force in International Law (2016), contains no chapter on collective self-defence, and existing literature on collective self-defence focuses on specific aspects of the concept rather than engaging with it holistically. This book aims to address the fundamental questions on the content of the right based on a detailed examination of the existing jurisprudence. In the eight chapters, the author raises seminal questions on collective defence and provides responses through a solid theoretical underpinning and based on State practice and the International Court of Justice's (ICJ) observations in the Nicaragua case which laid the foundation for collective self-defence.
The analysis seeks to challenge assertions concerning the limited usage of collective self-defence and its historical links. Chapter 1 seeks to delineate the notion of collective self-defence in international law and examines whether it is an inherent right before considering what constitutes an act of self-defence, including whether lesser forms of support such as providing weapons or logistical support trigger collective self-defence. Chapter 2 probes the origins of collective self-defence prior to 1945, examining how they contributed to the modern concept of collective self-defence which has now attained customary status.
The subsequent chapters examine the legal requirements for the exercise of collective self-defence. Chapter 3 outlines the criteria for exercising collective self-defence, which are shared with the individual right of self-defence, before examining how the criteria operate specifically in the context of collective self-defence actions. Chapter 4 examines the two additional criteria unique to collective self-defence outlined by the ICJ in the Nicaragua case: the requirements that the State ‘declare’ it has been attacked and that it ‘requests’ aid in its defence. The author argues that the first requirement has no legal basis, but the latter is binding, supported by opinio juris and the subsequent Oil Platforms and Armed Activities cases.
Chapters 5 and 6 examine the contours of the request requirement. The first key point is that it is the State which must request aid; there cannot be collective self-defence of a non-State actor. Chapter 5 considers how the de jure Government of the State can be identified for the specific purpose of issuing a collective self-defence request. The author contends that effective control cannot be the sole factor, but instead, multiple factors must be considered, including the democratic credentials of the requestor and external recognition. Chapter 6 addresses the manner and the form of the request, considering aspects such as whether it can be open-ended or must be targeted at particular States, the form in which it is made, and whether it needs to be made publicly, as well as the timing, noting that the request must be issued prior to the commencement of the use of force.
In Chapter 7, the author studies the various treaty arrangements on collective self-defence in the post-United Nations (UN) era to map common themes. Chapter 8 analyses the relationship between collective self-defence and military assistance on request (counter-intervention), which has rarely been explored by scholars. In many ways these concepts are similar, and they do overlap, with States often blurring the distinction. However, it is important to note that they differ at the conceptual level, as military assistance implicates the right of a State to not have another State using force in its territory, whereas in collective self-defence the situation is complex as the rights of at least three States are involved. Also, an act taken in exercise of collective self-defence remains prima facie a legal wrong, albeit with a valid defence, whereas military assistance is not a wrongful act. From a practical standpoint, States argue in favour of the possible use of force both as collective self-defence and military assistance on request. The remainder of the chapter examines the various legal requirements applicable to each doctrine, in order to highlight the similarities and differences in the operation of the two concepts.
In summary, the book provides a descriptive study of the contours of collective self-defence, which has received very limited scholarly attention. It debunks the misconception of collective self-defence as a mere post-UN development, tracing the historical events that contributed to the progressive development of the doctrine. Since collective self-defence has the potential to escalate any ongoing tensions, legal regulations ensure its legitimate application. Whilst the book is a useful contribution to scholarship, its value would have been greater if it engaged more with collective self-defence vis-à-vis non-State actors, which better reflects modern-day conflicts. Additionally, some discussion of the motives for States to trigger collective self-defence, beyond the strict confines of the legal provisions, would have enabled a more holistic appraisal of the doctrine.
