The Catholic Church runs the oldest legal system still working in the West
Catholic canon law has courts, judges, advocates, written codes and penalties, and it has operated without a break since long before European common law or civil law existed. By the nineteenth century it had swollen to some 10,000 rules, many contradicting each other, until a pope ordered a clean single-volume code.
Religious law covers the moral and legal codes of faith traditions: Jewish halakha, Islamic sharia, Hindu law, Christian canon law and others. Some apply only to believers; in certain states civil authorities enforce them on everyone. Buddhist monks and nuns follow the Patimokkha, a code of 227 rules. Baháʼí law, drawn from Bahá'u'lláh's writings, leans heavily on conscience, though it includes firm duties such as a daily prayer and a nineteen-day fast each March for healthy adults aged 15 to 70, and it forbids gossip and backbiting.
The word canon comes from Greek and Hebrew terms for a measuring rod or standard. The earliest canons were rulings of church councils, gathered from the first century onward and later supplemented by papal letters answering disputed questions, summed up in the maxim that once Rome has spoken the case is closed. A monk named Gratian produced the first truly systematic collection, and Pope Gregory IX issued the first official one in 1234. Later additions by Boniface VIII in 1298 and Clement V in 1317 joined Gratian's work to form the Corpus Juris Canonici.
Pius X launched a full codification to tame the accumulated tangle, and under Cardinal Pietro Gasparri the result was promulgated by Benedict XV, taking effect in 1918. After the Second Vatican Council closed in 1965, revision became unavoidable, and John Paul II issued a new code of 1,752 canons in 1983, followed in 1990 by a separate code for the Eastern Catholic Churches.
Canon law shaped secular law across Europe and Latin America, leaving marks on both civil and common law traditions. Church judges and certain officials still need advanced degrees in the subject, and its patron saint is Raymond of Penyafort, a Spanish Dominican who lived from 1175 to 1275.
Source: Religious law
