In Western culture, canon law is the law of the Roman Catholic and Anglican churches. The Eastern Orthodox concept of canon law is similar to but not identical to the more legislative and juridical model of the West. In both traditions, a canon is a rule adopted by a council (From Greek kanon/κανον, for rule, standard, or measure); these canons formed the foundation of canon law. In the official Church of England, the ecclesiastical courts that formerly decided many matters such as disputes relating to marriage still have jurisdiction of certain church-related matters; their jurisdiction dates back to the middle ages. In contrast to the other courts of England the law used in ecclesiastical matters is a civil law system, not common law.
In the Roman Catholic church, the canons of the councils were supplemented with decrees of the Popes, which were gathered together into collections called decretals.
In the 20th century, the Roman Catholic Church began attempting to codify canon law, which two millennia of development had become a complex and difficult system of interpretation and cross-referencing. The first code of canon law was published in 1917. A revised code, the Codex Iuris Canonici (Code of Canon Law, CIC) was published in 1983. Canon law within the Catholic Church is a fully developed legal system, with all the familiar trappings of courts (including lawyers); the highest degree of education in canon law is the J.C.D. (Juris Canonis Doctor, Doctor of Canon Law).
The Eastern Catholic Churches have a separate code of canon law. The first attempt to codify Eastern law under the name Codex Iuris Canonici Orientalis (Code of Eastern Canon Law) was partially completed when Pope Pius XII promulgated portions of the canons in 1948. However, when the project neared completion in 1959, Pope John XXIII suspended work as the expected conciliar reforms would affect the code. The Codex Canonum Ecclesiarum Orientalium (Code of Canons of the Eastern Churches, CCEO) was promulgated in November 1990. The majority of canons correspond closely to the Roman code, but incorporates certain differences in the hierarchy, administration and other areas.
The Orthodox Christian tradition is generally much less legalistic, and treats many of the canons more as guidelines than as absolute laws, adjusting them to cultural and other local circumstances. Some Orthodox canon scholars point out that, had the Ecumenical Councils (which deliberated in Greek) meant for the canons to be used as laws, they would have called them nomoi/νομοι (laws) rather than kanones/κανονες (standards).
Greek-speaking Orthodox have collected canons and commentary upon them in a work known as the Pedalion/Πεδαλιον (rudder--so called because it is meant to "steer" the Church). However, this is not a codification, but simply a compilation of one tradition of interpretation of the canons.