They deal mostly with the office and duties of a Christian bishop, the qualifications and conduct of the clergy, the religious life of the Christian flock (abstinence, fasting), its external administration (excommunication, synods, relations with pagans and Jews), the sacraments (Baptism, Eucharist, Marriage); in a word, they are a handy summary of the statutory legislation of the Early Church.
[1] The original Greek text claims the Apostolic Canons are the very legislation of the Apostles themselves, at least as promulgated by their great disciple, Clement.
Nevertheless, the Catholic Encyclopedia considers their claim to genuine Apostolic origin is "quite false and untenable" despite the fact that they are "a venerable mirror of ancient Christian life and blameless in doctrine".
Dionysius made three versions of the Apostolic Canons; it is the second of these versions which obtained general European currency by its incorporation as the opening text of his famous Latin collection of canons (both synodal decrees and papal decretals) known as the Dionysiana Collectio,[a] made public in the first decade of the 6th century.
borrowed from him; the text passed into Pseudo-Isidore, and eventually Gratian included (c. 1140) some excerpts from these canons in his Decretum, whereby a universal recognition and use were gained for them in the law schools.
At a much earlier date Justinian (in his Sixth Novel) had recognized them as the work of the Apostles and confirmed them as ecclesiastical law.
[1] The influence of the Apostolic Canons was greatly increased by the various versions of them soon current in the Christian Church, East and West.
They were also translated (more or less fully) into Syriac, Arabic, Coptic, and Armenian; in general they seem to have furnished during the 5th and 6th centuries a large element of the ecclesiastical legislation in the Eastern Church.