Der Einfluss der Kanonistik auf die Europäische Rechtskultur, Bd. 6: Völkerrecht ed. by Orazio Condorelli, Franck Roumy and Mathias Schmoeckel (review)

One of a generation of medievalists who, in the aftermath of World War II, researched and held positions with equal facility on both sides of the Atlantic, Peter Landau (1935-2019) left a powerful legacy not only of critical editions, articles, monographs, and textbooks but of scholars trained in legal history. A prolific writer who engaged not only with the medieval legal tradition (civil, canon, and natural law) but Protestant and modern law and history, Professor Landau also played key roles in associations devoted to legal studies, including the Max Planck Institute for the European History of Law and the Stephan Kuttner Institute of Medieval Canon Law. The weighty collection of essays on canon law's impact on international law under review here (in a journal co-edited by Professor Landau for decades) is therefore fittingly dedicated to his memory.

The modern world's globalized culture means that international law is more relevant than ever before, as increasingly international governance and alliances determine not merely war and peace but economies and environmental welfare. The twentieth and twenty-first centuries have thus far been dominated by the tension between residual national, ethnic, and religious loyalties and international collaboration, by Axes and Allies, the League of Nations, NATO, the Warsaw Pact, NAFTA, OPAC, the World Bank, RPEC, the European Union, and Brexit. In order to understand the expectations concerning international law which those cultures heavily shaped by European legal traditions brought and still bring to the bargaining table, a consideration of canon law's effect on medieval and early modern international law is essential. But what falls under the purview of international law and what are its bases? The Roman advocate and politician Cicero and other Roman jurists viewed the ius gentium (literally: law of the peoples), as stemming from human consent, as equal in primacy to natural law, and as truly independent from civil law (ius civile), which applied only to individual countries.

However, as the introduction (v-xxii) and Peter Landau's article (xxiii-xxv) explain, most pre-modern canon lawyers adopted their definition of international law from Isidore of Seville's vastly influential Etymologiae. As a bishop, Isidore hybridized Christian morality with the Roman legal tradition and concepts of universal human obligations. He defined the ius gentium as an universal collection of rules originating from human nature, not legislation; international law was used by nearly all peoples to limit strife and uncertainty and therefore dealt with occupation, construction of fortifications, weapons, warfare, prisoners, slavery, the right of return, peace treaties, armistices, the inviolability of ambassadors, and the prohibition of marriage between those of different origins. Isidore's definition was incorporated into the foundational textbook for medieval canon law, Gratian's Decretum. His list of topics therefore provided canonists with focal points for discussion and could well serve as the table of contents for this volume, which also compares medieval concepts of international law to those of other periods (vi-vii).

Contracts Must Be Observed But Can Be Broken

The volume proper begins with Franck Roumy's investigation of the canonical origins of the clausula rebus sic stantibus (the ability to cease observing or to revise a contract or treaty should the circumstances under which it was originally formulated change to the significant detriment of either party). As Roumy notes, James Muldoon and many others have elucidated the ways in which rules and principles established by medieval canon lawyers influenced modern international law. The particular clausula discussed here was adopted by the pioneering Italian jurist Alberico Gentili (1552-1608), who argued that juridical principles governing private contracts were transferable to conventions between powerful sovereigns. After Gentili, common opinion decreed that the clausula applied to every accord...