Canon law is the West’s oldest continuously working legal system
Legal history asks how rules evolve inside civilizations. Egyptian Ma’at ideals reach toward 3000 BC; Ur-Nammu’s Sumerian code by the twenty-second century BC is among the earliest surviving casuistic law lists. Catholic canon law, though younger than Rome’s, is the West’s oldest continuously functioning system.
Around 1760 BC Hammurabi had Babylon's laws carved on stelae and set up across his kingdom for anyone to read; British Assyriologists found the best-preserved copy in the 19th century. Greek had no single abstract word for law, separating divine law, human decree and custom, yet Greek cities pioneered democratic constitutions. In India the Arthashastra and the Manusmriti, whose tolerant, pluralist outlook was cited across South East Asia, served as authoritative guides; later the Mughal emperor Aurangzeb sponsored the Fatawa-e-Alamgiri, before British rule installed common law.
Roman law, shaped by Greek thought, relied on lay judges called iudices, and precedents went unreported. In the 6th century Justinian consolidated Rome's legal mass into the Corpus Juris Civilis, keeping about a twentieth of the earlier texts. The West never officially received it: post-Roman rulers used the Theodosian Code for natives and Germanic custom for newcomers, settled orally by lawspeakers. Charlemagne centralised royal courts, but after his realm fractured, law became local and customary until 11th-century crusaders brought Byzantine texts home and Bologna's scholars began applying Justinian to their own customs.
Islamic jurists developed hawala, an informal value-transfer system mentioned as early as the 8th century that later influenced the French aval. Canon law, younger than Roman law but older than modern civil codes, mixed with secular law to form the jus commune. Merchants meanwhile built the Law Merchant on Scandinavian customs and the Hanseatic League, stressing freedom of contract.
After the Norman conquest, English royal judges built the precedent that became common law. Henry II ran courts from Westminster with travelling judges, and his Assize of Clarendon in 1166 expanded jury trial at the expense of trial by combat. Continental Europe instead turned to codes: the Napoleonic Code and Germany's Bürgerliches Gesetzbuch proved easy to export. Japan modernised largely on the German model, late-Qing China followed Japan, and Taiwan still keeps closest to those codes.
Source: Legal history
