The dissertation analyzes the state of scientific development of the problem of medieval canon law, the main directions of modern research and the latest approaches to the interpretation of legal monuments. The contribution of ‘national schools’ to the study of church law in the study of canon law of the classical Middle Ages is established. The impact of external factors on the development of the history of canon law is noted.
The main categories of sources that provided Gratian with materials for the “Decretum” are identified: canons of church councils, papal decretals, penitentials, patristic texts, Roman law, Carolingian capitularies, as well as part of forged legal texts, theological and non-canonical sources of the previous eleven centuries. The justification, nature and details of citing biblical texts and pseudo-apostolic literature in the form of the so-called ‘canons of the apostles’ are analyzed. It is noted that the texts of early church law entered the modern codification of the law of the Catholic Church only thanks to Gratian's “Decretum”. The available data and historiographical tradition regarding the personality of Gratian are analyzed: his name, origin, place of birth, education, membership of the black or white clergy, scientific qualifications, place of work and writing of his works, date of creation, sources of borrowings and stages of composition of the text of the “Decretum”, dates and places of death of the canonist.. The direct sources of Gratian's work have been clarified – pre-Gratian canonical collections, namely: “Panormia” and “Collectio Tripartita” by Ivo of Chartres, “Collection of Canons” by bishop Anselm of Lucca (1036–1086), “Polycarp” (ca. 1111–1113) by the cardinal-deacon Gregory with the title of St. Chrysogonus, “Collection in Three Books” (1113-1120), “Liber de misericordia et Justitia” by Alger of Liège, “Etymologies” by Isidore of Seville, “Sentences of Magister A.”, probably by Elmer of Canterbury. The structure and content of the “Decretum”, Gratian's research method, further development of canon law as a university discipline within the framework of decretistics and decretalistics, post-Gratian decretal ‘collections’ that were included in the “Corpus of Canon Law” are analyzed. It has been established that the main stages of the formation of the "Corpus of Canon Law" are: 1) the writing by Gratian of the “Concordia discordantium canonum” or “Decretum” (c. 1240); 2) publication in 1234 of the “Decretales” or “Liber extra” of Pope Gregory IX (1227–1241), the author of the ‘collection’ was the dominican Raimondo da Peñafort; 3) law-making activity of three Roman pontiffs of the late 13th–early 14th centuries: “Liber sextus decretalium” of Pope Boniface VIII (1294–1303), “Clementinae” or “Constitutions” of Pope Clement V (1305–1314) and “Extravagantes” and “Extravagantes Communes” of Pope John XXII (1316-1334).
