The ius commune law of war: Giovanni da Legnano's 'De bello' and the medieval origins of international public law

In the "calamitous" fourteenth century, to borrow Barbara Tuchman's phrase, a scholar at the University of Bologna fused existing Roman and canon law into a true ius commune law of war. Giovanni da Legnano (ca. 1320--83) was the first to deal systematically in a single work with legal questions arising from war and other forms of legitimized violence and this study demonstrates that he did so, in part, to reconcile legal theory with political and military changes that were taking place across Europe. This dissertation analyzes two of Giovanni's works (De bello and De represaliis), and argues that they not only summarized and systematized the work of previous medieval thinkers, they also formed the framework within which later writers constructed the early modern international law of war.; Scholars studying medieval legal theory will find that this work provides important information on the evolution of the law of war in the later middle ages. It is also a useful case study detailing the development of one aspect of the ius commune, both in Giovanni's equal reliance on Roman and canon law principles and in his reconciliation of the learned laws with local laws, customs and everyday practice. The analysis will be of interest to scholars studying the origins of public international law as well; more and more it is recognized that early modern and modern theories are part of a tradition that extends back into the middle ages. Little work, however, has been done on the late medieval texts which formed an important part of this earlier tradition. This dissertation, therefore, fills a gap in our knowledge about the origins of international law, and discusses in-depth for the first time two texts which provided an essential link between medieval theories on state sanctioned violence and those of the early modern and modern periods.