Dominique Bauer 43 Ivo of Chartres, the Gregorian Reform and the Formation of the Just War Doctrine Dominique Bauer Senior Lecturer, Law Faculty, Tilburg University, Netherlands in cooperation with Randall Lesaffer Professor of Legal History, Tilburg University; Professor of Law, Catholic University of Leuven, Belgium 1. A Missing Link in the History of the Just War Doctrine Few will dispute that the just war doctrine historically has been among the most influen- tial and enduring legacies of the Late Middle Ages. Before the United Nations Charter of 1945, the doctrine formed the backbone of the ius ad bellum as it had been understood by writers and been paid lip service to by rulers since the Late Middle Ages.1 The just war doctrine obtained its classical outline during the thirteenth century. As in many matters of theology and political theory, Saint Thomas Aquinasʼs (1225-1274) synthesis gained canonical authority and outlived the ages as the common denominator for the doctrine. Of course, this did not mean that afterwards there were no variations on the theme. According to Aquinas, for a war to be just three conditions had to be fulfilled. First, the belligerent needed authority (auctoritas principis). In practice, this meant that only the Church or a secular prince who did not recognise a higher authority2 had the right to wage or authorise war. A ruler who did not enjoy ʻsovereigntyʼ could turn to his superior to have his rightful or supposedly rightful claim upheld. Second, a war had to be waged for a just cause (causa iusta). This could either be self-defence against prior armed ag- gression, the recovery of lost property or the restoration of injured rights. Some writers also recognised as just cause the meting out of punishment for injustice committed. Third, the belligerent needed to be righteous himself (recta intentio). His goal had to be the promotion of good and the avoidance of evil. In practice, this meant that the war had to aim at the restoration of justice and peace.3 While the first two conditions are of a more legal nature, the third one is of a moral nature. Over time, jurists would come to play down this third condition or treat it as irrelevant and void of any substance. The elaboration of the just war doctrine had already started during the Renaissance of the Twelfth Century (1070-1225). The synthesis Aquinas and other late-medieval 1 Randall Lesaffer, “War, Peace, Interstate Friendship and the Emergence of the jus publicum Europaeum” in Ronald G. Asch, Wulf E. Voß and Martin Wrede (eds.), Frieden und Krieg in der frühen Neuzeit, Munich 2001, 87-113, at 96-101. 2 “Superiorem non recognoscens” as the great commentator Bartolus of Sassoferrato (1314- 1357) would have it; Tractatus de reprisaliis, 3, 2. Journal of the History of International Law 7: 43–54, 2005. ©2005 Koninklijke Brill NV. Printed in the Netherlands. 44 Journal of the History of International Law scholastic writers made was rooted in three textual traditions: that of the theologians, the Roman civil lawyers and the canon lawyers. Although they were three autonomous disciplines, which had developed their own intellectual establishment and institutions, the three traditions certainly had not developed completely independently from one another. Between the three traditions, the canonist logically held the middle ground and had played a central role in the development of the doctrine of the just war. In modern historiography, the honour of having laid down the first consistent and the first truly legal doctrine on the just war is by and large attributed to Gratian, the author of the Concordia Discordantium Canonum, better known as the Decretum Gra- tiani (around 1140).4 The Decretum forms the oldest part of what was, in the sixteenth century, to become the Corpus Iuris Canonici, the authoritative text of canon law, and it forms the starting point of classical canon law.5 As he did with all the questions he treated, Gratian, in the formulation of his just war theory, made use of a wide range of biblical, theological and canonical sources. As most modern students of the just war doctrine have indicated, Gratian particularly referred to the Church Fathers Saint Augustine (354-430) and Saint Isidore of Seville (560-636). In contemporary scholarship, the common view is that they, together with the Roman orator Marcus Tullius Cicero (106-43), are the main authors who developed some relevant thought about the justice of war prior to Gratian and that the latter has constructed a consistent theory out of their disparate and loose remarks. Gratianʼs is also the merit of having formulated – at least partly – the just war in legal, and not in moral or theological terms. Although most surveys of the history of the just war doctrine acknowledge that some older canonical collections, such as those of Burchard of Worms (ca. 1012), Anselmus of Lucca (ca. 1083) and Ivo of Chartres (ca. 1095), include frag- ments relevant to the just war and that Gratian has made use of those,6 their ʻjust war doctrinesʼ have not been thoroughly studied in their own right.7 By consequence, the assessment of their true significance for the evolution of the just war doctrine remains 3 Peter Haggenmacher, Grotius et la doctrine de la guerre juste, Paris 1983, 167-168; Frederick H. Russell, The Just War in the Middle Age, Cambridge 1975, 268-271; Joachim von Elbe, “The Evolution of the Concept of the Just War in International Lawʼ, American Journal of International Law, 33 (1939) 665-688, at 669. 4 Esp. C 23 q 2. – Haggenmacher, Grotius et la doctrine de la guerre juste, 84-91; Maurice H. Keen, The Laws of War in the Late Middle Ages, London 1965, 66; Russell, The Just War in the Middle Ages, 55-57. 5 On the Decretum Gratiani, Anders Winroth, The Making of Gratianʼs Decretum, Cambridge 2000. 6 Mostly so by Haggenmacher, Grotius et la doctrine de la guerre juste, 28-29, and Georges Hubrecht, “La juste guerre dans le Décret de Gratien”, Studia Gratiana, 11 (1955) 159-177, at 163. 7 Most relevant studies concerning the period before Gratian are on the theme of the holy war and the crusades, e.g. James Brundage, Medieval Canon Law and the Crusader, Madison etc. 1969, and idem, The Crusades, Holy War and Canon Law, Aldershot 1991. .