The legal history of the Catholic Church is the history of the oldest continuously functioning legal system in the West much later than Roman law but predating the evolution of modern European civil law traditions. The history of Latin canon law can be divided into four periods: the jus antiquum, the jus novum, the jus novissimum and the Code of Canon Law. In relation to the Code, history can be divided into the jus vetus (all law before the Code) and the jus novum (the law of the Code, or jus codicis). Eastern canon law developed separately.
The most ancient collections of canonical legislation are certain very early Apostolic documents, known as the Church Orders: for instance, the Didache ton dodeka apostolon or "Teaching of the Twelve Apostles", which dates from the end of the first or the beginning of the 2nd century; the Apostolic Church-Ordinance; the Didascalia, or "Teaching of the Apostles"; the Apostolic Canons and Apostolic Constitutions. These collections have never had any official value, no more than any other collection of this first period. However, the Apostolic Canons and, through it, the Apostolic Constitutions, were influential for a time in that later collections would draw upon these earliest sources of Church law.
It was in the East, after Constantine I's Edict of Milan of toleration (313), that arose the first systematic collections. We cannot so designate the chronological collections of the canons of the councils of the 4th and 5th centuries (314-451); the oldest systematic collection, made by an unknown author in 535, has not come down. The most important collections of this epoch are the Synagoge kanonon, or the collection of John the Scholastic (Joannes Scholasticus), compiled at Antioch about 550, and the Nomocanons, or compilations of civil laws affecting religious matters (nomos) and ecclesiastical laws (kanon). One such mixed collection is dated in the 6th century and has been erroneously attributed to John the Scholastic; another of the 7th century was rewritten and much enlarged by the schismatical ecumenical patriarch Photius (883).