Biblical Foundation
Gratian's Concordia Discordantium Canonum ('A Harmony of Conflicting Canons,' c. 1140), universally known as the Decretum, is the foundational systematisation of medieval canon law. Its biblical roots run throughout the text. The Decretum opens with a definition of natural law derived directly from Scripture: 'The human race is ruled by two things, namely natural law and customs. Natural law is what is contained in the Law and the Gospel, by which each person is commanded to do to others what he wants done to himself and forbidden to do to others what he does not want done to himself.' The Golden Rule of Matthew 7:12 ('Do to others what you would have them do to you') is athe foundation of Gratian's entire jurisprudential project - connecting the biblical commandment to the natural law tradition of Cicero and Augustine.
Deuteronomy 17:8-13 - the provision for a supreme court of priests and judges to adjudicate difficult cases in Israel - provided Gratian with a biblical model for hierarchical ecclesiastical jurisdiction. The passage prescribes a system of appeal from local judges to a central tribunal for cases that cannot be resolved at the lower level, with binding authority over the whole community. Gratian interpreted this as a divine warrant for the hierarchical structure of canon law, in which local bishops' courts gave way to provincial councils and ultimately to papal authority - a structure mirroring the Deuteronomic judicial hierarchy.
Matthew 18:15-17 - 'If your brother or sister sins, go and point out their fault, just between the two of you... if they will not listen, take one or two others along... if they still refuse to listen, tell it to the church' - provided a biblical procedure for ecclesiastical discipline that Gratian incorporated into his treatment of judicial process. The stages of Matthew 18 - private admonition, witnessed confrontation, community judgment - became the canonical basis for the Church's disciplinary procedures, including the trial of clerics. Romans 13:1-4 provided the theological basis for Gratian's treatment of the relationship between ecclesiastical and secular authority.
Historical Transmission
Gratian wrote in Bologna around 1140, benefiting from the same intellectual environment that produced the revival of Roman law under Irnerius and his successors. His method - citing conflicting canonical authorities on each question, then resolving the conflict through rational distinctions - was the dialectical method applied to law, drawing on Abelard's Sic et Non as a model. The result was not a mere compilation but a systematic science of law: Gratian created the discipline of canon law as an academic subject, giving it the rigour and coherence that would make it the model for subsequent European legal systematisation.
Harold Berman, in Law and Revolution (1983), identifies the Gregorian Reform of the late eleventh century and the Decretum as the beginning of the Western legal tradition proper. Berman's argument is that the Decretum, by systematising the Church's law into a rational, self-contained legal science, created a model that secular legal systems subsequently imitated and that established the idea that law is a coherent, developing, rational body of rules separate from politics and custom. The common law of England, the Roman law revival of continental Europe, and the subsequent development of civil law traditions all reflect the influence of Gratian's canonist model.
The canonists trained in Gratian's tradition - the Decretists, followed by the Decretalists who commented on subsequent papal decretals - became the most skilled lawyers in medieval Europe. They staffed royal chanceries, served as judges, negotiated treaties, and advised rulers. Through these professionals, canonical learning shaped secular law far beyond the formal jurisdiction of Church courts. English common law absorbed canonical procedure, evidence rules, and substantive categories through canonist-trained royal judges and through the ecclesiastical court system that operated alongside the secular courts until the Reformation.
Modern Application
The influence of Gratian's Decretum on Western law is pervasive and largely invisible - the water in which modern legal thought swims. The adversarial model of judicial proceedings, the requirement of proof beyond reasonable doubt in serious cases, the distinction between criminal and civil liability, the concept of equity as a corrective to strict positive law, the idea that law must be consistent and that conflicts between legal rules must be resolved by rational principles - all these derive substantially from the canonist tradition Gratian inaugurated.
The Decretum's specific biblical roots - Matthew 18's three-step disciplinary procedure, Deuteronomy 19:15's two-witness rule, the Golden Rule of Matthew 7:12 as natural law foundation - are the biblical arteries supplying the canonical body of law that shaped Western legal thought. Where contemporary law reflects commitment to fair procedure, protection of the accused, hierarchical review of lower court decisions, and the idea that law participates in a higher moral order, it reflects - through many layers of mediation - the biblical legal theology that Gratian made central to the Western legal tradition. John Witte Jr.'s work on canon law and Western legal history documents this inheritance in scholarly detail, demonstrating that the story of Western law cannot be told without the story of the Bible's reception in the canonical tradition.
Gratian and the Scientific Method in Law
Gratian's contribution to legal history extends beyond the specific substantive rules he derived from Scripture. His dialectical method -- presenting conflicting authorities and resolving them through principled distinctions -- established a model of legal science that influenced both canon law and the common law tradition. The method assumed that apparent contradictions between authoritative sources could always be resolved through rational analysis: by attending to the precise meanings of terms, the specific contexts of different rules, and the hierarchical relationships between different authorities. This assumption -- that law is a rational, coherent system rather than a collection of unrelated commands -- is one of the most consequential intellectual commitments in the history of Western legal thought.
The model of Gratian's Decretum -- a systematically organised, comprehensively annotated collection of legal materials, with learned commentary that addresses conflicts and provides principled resolutions -- influenced every subsequent attempt at legal codification. Justinian's Corpus Juris Civilis (534), which Gratian knew and used, had provided a Roman model for legal systematisation; Gratian Christianised and modernised the model, applying it to the accumulated ecclesiastical legislation of twelve centuries. The result was the first genuinely scientific legal textbook in European history, and it served as the model for legal education and legal scholarship across Europe for the next four centuries. The tradition of legal scholarship that Gratian inaugurated -- rigorous, systematic, critical -- is the direct ancestor of the modern legal academy.