An examination of the scope of States' right of self-defence under Article 51 of the UN Charter in the post-9/11 security environment.

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.

Introduction; 1. The methodological debate and the quest for custom; 2. Conditions of self-defence; 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?