Hague Academic Press, a T.M.C. Asser Press imprint Self-defence may be used as a defence for the use of force in order to prevent crime against oneself, a fellow human-being or property. Although traditionally linked to the concept of armed attack, new forms of aggression, the concept of collective security and an increasing interaction between national and international law have forced a reassessment of self-defence. The first Hague Colloquium on the Fundamental Principles of Law on the topic of self-defence brought together experts from both academic and professional circles to debate the notion of self-defence. Both the Colloquium and this subsequent publication make a valuable contribution to the development of the law by recognising the sources of the principle of self-defence, and the theories behind it, by following its path of evolution and by reassessing its current status.