The myth of liberum ius ad bellum: Justifying War in 19th-century legal theory and political practice

Abstract

The proposition of so-called liberum ius ad bellum claims that European states in the 19th century were no longer bound by the moral criteria of just war (bellum iustum) but that they held a sovereign right to go to war. This thesis is widely accepted among scholars of the history of international law and international relations alike. Nevertheless, the realist perspective on international relations was challenged in 19th-century international legal discourse. Several contemporary international lawyers were in favour of the legalization of international relations in order to legally ban unilateral war. Not much attention has so far been paid to the controversial debate on liberum ius ad bellum, which appears particularly in late 19th-century legal treatises. In the present article, this dispute will be analysed by comparing different normative justifications and criticism of war in 19th-century international legal doctrine. As will be shown, by confronting legal doctrine with contemporary state practice, the narrative of liberum ius ad bellum constitutes a myth in the history of international law.