The beginning of canon law may be seen in the New Testament (see Acts 15; 1 Corinthians 11). During the 2nd and 3rd centuries a number of Church orders (for example, the Didache and the Apostolic Tradition) described as normative certain customary practices of the community. Canon law in the sense of enacted legislation originated in the 4th-century regional councils held in Asia Minor. The enactments of these councils (Ancyra, Neocaesarea, Antioch, Gangra, and Laodicea), together with those of the ecumenical councils of Nicaea (325), Constantinople (381), and Chalcedon (451), formed the nucleus of subsequent collections. They dealt with the structure of the Church (the provincial and patriarchal organization), the dignity of the clergy, the process of reconciling sinners, and Christian life in general.
The oldest Greek canonical collection preserved in the original text is the Synagoge Canonum (around 550) in 50 titles by Johannes Scholasticus. Instead of a chronological arrangement, the canons are grouped systematically according to subject matter. Another innovation was the accordance of canonical authority to rulings of Church fathers, especially St Basil. The Council of Trullo (692), in giving formal approval to the preceding conciliar legislation and patristic writings, established the basic code for the Eastern Churches that is still normative for the Orthodox.
In the West, the most important canonical collection of the early centuries was made in the 6th century by Dionysius Exiguus. He translated into Latin the canons of the Eastern councils and added 39 papal decretals. The rulings of the popes were thus put on a level with conciliar law. After the disintegration of the Roman Empire, canon law developed independently in the different kingdoms. National collections were made in which local legislation, intermingled with elements of Germanic law, were added to the ancient code. Because conciliar activity was particularly intense in Spain, the collection known as the Hispana (later called the Isidoriana after St Isidore of Seville) proved to be outstanding. Of great significance for the future was the institution of the practice of private penance by the Irish monks.
Collections made at the time of Charlemagne (in around 800) and the Gregorian reform in around 1050 reflect the attempt to restore traditional discipline. Great confusion persisted, however, insofar as certain practices accepted in the Germanic law and the penitentials (for example, remarriage after adultery) were in conflict with the programme of the reformers. Ivo of Chartres prepared in about 1095 a set of rules and principles for interpreting and harmonizing texts. The actual work of harmonization was done in about 1140 by Gratian, who is called the father of the science of canon law. Shortly after the revival of Roman law studies at the University of Bologna, Gratian collected all the canon law from the earliest popes and councils up to the Second Lateran Council (1139) in his Decretum, or Concordance of Discordant Canons. With its appearance the period of the ius antiquum came to a close.
The scientific study of law stimulated by the Decretum encouraged the papacy to resolve disputed points and supply needed legislation, thus inaugurating the ius novum. Over the next century thousands of papal decretals were issued and gradually collected in five compilationes. Compilatio Tertia, consisting of decretals from the first 12 years of his reign, was ordered by Innocent III in 1210 to be used in courts and law schools, thus becoming the first collection in the West to be officially promulgated. Gregory IX commissioned Raymond of Peñafort to organize the five compilationes in one collection, which was promulgated in 1234 and became known as the Extravagantes. Two other official collections were made later: the Liber Sextus (1298) of Boniface VIII and the Constitutiones Clementinae (1317). The Extravagantes of John XXII and the Extravagantes Communes were privately compiled. In 1503 the legist Jean Chappuis printed and published in Paris, under the title Corpus Iuris Canonici, the Decretum of Gratian and the three official and two private collections of decretals. The Corpus, along with the decrees of the Council of Trent (1545-1563), remained the fundamental law of the Roman Catholic Church until the Codex Iuris Canonici appeared in 1917. After the theological updating of the Second Vatican Council (1962-1965), it became necessary for the Roman Catholic Church to undertake a thorough revision of the 1917 code. A special commission was established in 1963, which in 1980 presented the draft of a completely new code. Pope John Paul II, after making a number of revisions, promulgated it on January 25, 1983; it took effect on November 27, 1983.
The Corpus continues to have some validity for the Church of England, which issued its first complete, free-standing Code of Canons in 1603. The medieval law is presupposed except where it has been affected by contrary statute or custom in England. These canons stood virtually unchanged until the mid-19th century, when a process of amendments began. The Convocations of Canterbury and York in 1964 and 1969 promulgated a fully revised code that nevertheless maintained the same understanding of the relationship between the present and the medieval tradition. Each of the national churches of the Anglican Communion (for example, Australia, the United States, and Canada) has its own canons, which may or may not directly reference those of the Church of England, though they are similar in format.
Plans have been under way for more than a quarter of a century for the first Great Synod of Eastern Orthodoxy to be held since the 8th century. Among the topics for further study is the codification of the Holy Canons. Current canon law developed largely in response to the Great Schism of 1054.