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Jieiken no Kisou (The Right of Self-Defence in International Law: From the Caroline Incident to the United Nations Charter)


MORI Tadashi


336 pages, A5 format




March 24, 2009



Published by

University of Tokyo Press

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Jieiken no Kisou

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The primary purposes of this book are to examine a long-standing dispute regarding the prerequisite for the exercise of the right to self-defence, by taking a historical perspective on the development of that concept from the mid-19th century to 1945; and to offer a possible better alternative for interpreting the significance of the precondition provided for in the Article 51 of the United Nations Charter.

Article 51 of the Charter provides that ‘Nothing in the present Charter shall impair the inherent right of individual or collective self-defence if an armed attack occurs against a Member of the United Nations.’ Although that prerequisite for the exercise of the right seems here to be set forth definitively (i.e. the occurrence of an armed attack against a state), there has in fact been a long-lasting dispute over the precondition, between the restrictive and the permissive interpretations. This dispute is sometimes even called a ‘confusion.’

In order to clarify this issue, the book discusses the function of the right to self-defence in that period, i.e. what the right justified, as well as the prerequisite for it. Focusing on the function, it is argued that the concept of the right to self-defence in the period may be divided into two main types, each with a different prerequisite: the ‘policing’ concept and the ‘counter-war’ concept. The former first emerged, in the pre-World War I era; and the latter, in the inter-war era, through the development of the outlawry of war in the 1920s. However, the latter did not negate the former; rather, these two types of self-defence coexisted during the inter-war era.

The ‘policing’ concept of the right of self-defence could be exercised in the circumstances in which State A was attacked by private persons, such as armed bands or terrorists, operating from within the territory of State B or from ships on the high seas under the flag state jurisdiction of State B. Military operations would then be carried out against those private persons, rather than against State B. However, in an inter-state relationship, the right justified State A’s violation of the territory or of the jurisdiction of State B; the right of this type could be exercised only when State B could not prevent private persons from attacking State A.

The ‘counter-war’ concept of the right of self-defence, whose function is the justification of the use of force, can be further subdivided into two types: collective and individual self-defence. Although collective self-defence has often been regarded as a new notion established by the United Nations Charter, a precursor of that right can in fact be seen in the inter-war era.

In the inter-war era, collective and individual self-defence differed in both function and prerequisite. Collective self-defence would authorize non-attacked states to use force in order to assist another state under attack; and individual self-defence would permit the use of force exclusively to a state under attack. The prerequisite for the former was the occurrence of an armed attack and for the latter was the use of force, including the use of force short of an armed attack. This differentiation in prerequisites was regarded as essential because collective self-defence was considered a potential cause of conflict with the collective security system, and even of world war.

This distinction in the prerequisite between collective and individual self-defence is not explicit in the provisions of the Charter; but it can be found in its travaux préparatoires. What the founders of the Charter intended was to restrict the prerequisite for collective self-defence without limiting individual self-defence to the occurrence of an armed attack. Nor is the ‘policing’ concept of the right of self-defence negated by article 2 (4) of the Charter. It is suggested that this is the significance of the precondition provided for in the Article 51 of the Charter.

Thus this book defines the right of self-defence as understood in and before 1945. However, clarification of that concept in contemporary international law requires an analysis of state practice since 1945, which is itself beyond the bounds of this book. On the other hand, such an analysis could be based on a framework employing the typology suggested here, which represents the strata of the concept. Thus the present book will hopefully contribute to the current debate regarding the right of self-defence.

(Written by MORI Tadashi, Professor, Graduate Schools for Law and Politics / 2017)

Related Info

English version:
"Origins of the Right of Self-Defence in International Law: From the Caroline Incident to the United Nations Charter" is published by Brill, on Feb 12, 2018
The 42nd Adachi Mineichiro Memorial Prize  (Adachi Memorial Foundation  Nov 2009)
Book Reviews:
Reviewed by MATSUDA Takeo  (“KOKUSAIHO GAIKO ZASSI – The Journal of International Law and Diplomacy” Vol.109, No.1  May 2010)

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