The two largest and oldest Christian denominations in the world today are the Roman Catholic Church (approximately 1.3 billion adherents) and the Eastern Orthodox Church (approximately 300 million adherents). Besides their core religious mission, both churches have complex, multi-layered systems of governance to help manage their geographically and culturally diverse communities of followers. A key aspect of these systems for the two churches is the administration of religious justice, known in the Christian tradition as ‘canon law’, to regulate church hierarchy, to settle disputes that fall outside the realms of civil or criminal law, and to provide a moral framework for believers’ lives. In the contemporary era, both Catholics and Orthodox have their own canonical courts, legal source-texts, and academically trained experts. However, the roots of these distinctive systems only began to emerge in the Middle Ages (especially c.1000–1300), a time when there was not yet any clear division between the two churches. Most Christians in medieval Eastern and Western Europe believed that they belonged to a single community until at least the thirteenth century. During this key period, relations between Western Christians under the spiritual leadership of the Roman papacy and Eastern Christians under the Byzantine Church of Constantinople degenerated into outright war, culminating in the Fourth Crusade of 1204.
This interdisciplinary project aims to build upon the work that I am currently undertaking as part of an RGC ECS grant on the relationship between developments in legal scholarship and religious identity in the Byzantine Empire during the 11th–13th centuries. While the subject of the ‘Great Schism’ between Western (Catholic) and Eastern (Orthodox) Christians in the Middle Ages has traditionally been studied from the perspective of theological and political ‘rupture points’, I approach the subject from the perspective of legal and institutional history. My hypothesis is that the parallel emergence of distinctive legal systems and religious identities in the two churches was not a coincidence; rather, the systematisation of separate judicial structures in Rome and Constantinople created a fundamental institutional incompatibility that heightened the sense of separate identity. The main output will be a substantial monograph, at least one peer-reviewed article, and three conference presentations.