'Armed Attack' and Article 51 of the UN Charter: Evolutions in Customary Law and Practice

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Cambridge University Press, Nov 25, 2010 - Law
This book examines to what extent the right of self-defence, as laid down in Article 51 of the Charter of the United Nations, permits States to launch military operations against other States. In particular, it focuses on the occurrence of an 'armed attack' - the crucial trigger for the activation of this right. In light of the developments since 9/11, the author analyses relevant physical and verbal customary practice, ranging from the 1974 Definition of Aggression to recent incidents such as the 2001 US intervention in Afghanistan and the 2006 Israeli intervention in Lebanon. The notion of 'armed attack' is examined from a threefold perspective. What acts can be regarded as an 'armed attack'? When can an 'armed attack' be considered to take place? And from whom must an 'armed attack' emanate? By way of conclusion, the different findings are brought together in a draft 'Definition of Armed Attack'.

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A monolith of legal analysis, this book exhaustively and thoroughly dissects and analyzes the concept of the "armed attack" within the meaning of Article 51 of the UN Charter. A comprehensive work, Ruys does an excellent job of highlighting and reminding the reader of his methodology and purpose, making sure to indicate where assumptions are being made, and what limitations his approach has. He makes it unequivocally clear to the reader what it is, exactly, he is trying to achieve, and recognizes the strengths and limitations of his approach.
A highly coherent, comprehensive, methodologically sound and logical work. It culminates in the draft "Definition of Armed Attack" - loosely modeled on the "Definition of Aggression" - which is an impressive and well-thought proposal. The most comprehensive, complete elucidation of the armed attack in contemporary international law is almost certainly found within this book.
Finally, it is a compelling read. Fluid writing with a constant awareness of methodology makes it easy for the reader to follow, so the "big picture" is never lost while delving into the details.
Highly recommended.


1 The methodological debate and the quest for custom
2 Armed attack and other conditions of selfdefence
3 The armed attack requirement ratione materiae
4 The armed attack requirement ratione temporis
5 The armed attack requirement ratione personae
6 What future for the armed attack criterion?

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About the author (2010)

Dr Tom Ruys is a lawyer with Stibbe, Brussels, and a senior member of the Leuven Centre for Global Governance Studies. He also teaches public international law and humanitarian and security law as a substitute lecturer at the Catholic University of Leuven.

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