Gratian's Decretum and the Text That Made Canon Law an Academic Discipline

Canon law existed as scattered conciliar decrees, papal letters and patristic rulings for a thousand years before it became a discipline anyone could actually study as a coherent body of law. The change is usually dated to around 1140, when a teacher working in Bologna named Gratian compiled the Concordia discordantium canonum, the Harmony of Discordant Canons, later known simply as the Decretum, a systematic collection that did not merely gather earlier rulings but applied a dialectical method borrowed from the scholastic study of theology, setting apparently contradictory texts against one another and working out principles for reconciling or ranking them rather than leaving the contradictions standing.

Bologna already housed a flourishing school of Roman civil law, and Gratian's Decretum let canon law claim a parallel academic footing there, taught, argued and glossed by professional canonists using the same scholastic techniques civil lawyers applied to Justinian's Corpus Juris Civilis. Later medieval popes issued further authoritative collections building on Gratian's model, eventually gathered together as the Corpus Juris Canonici, the body of canon law that governed the Western church for centuries afterward and that the 1917 and 1983 Codes of Canon Law both descend from in method if not in wording. Gratian is still called the father of the science of canon law for exactly this reason: he did not write the rules the church already had, he gave the study of those rules a method rigorous enough to be taught as a university subject in its own right.