A Doctrinal Study on the Evolution of Self-Defence in International Law

This study explores the evolution of the concept of self-defence in international law, tracing its roots from ancient civilizations through theological interpretations to the contemporary legal framework established under the United Nations Charter.By examining historical doctrines such as the Just War Theory and the perspectives of thinkers like Cicero, Augustine, Aquinas, Vitoria, Gentili, and Grotius, the research highlights how the notion of self-defence has been shaped by philosophical, religious, and legal traditions.The work further evaluates the shift from natural law to positivist interpretations following the Peace of Westphalia, and the codification of self-defence as a right of states in response to imminent threats, particularly after the Caroline incident.Emphasis is placed on the interplay between necessity, proportionality, and immediacy as core principles governing the lawful use of force in self-defence.This doctrinal study ultimately illustrates how self-defence has remained a vital and adaptive principle of international law, balancing the imperatives of state sovereignty and global peace.