Ancient Rome's legal tradition is one of its most durable contributions to Western civilization. Roman law, developed over centuries of practical jurisprudence and compiled in Justinian's Corpus Juris Civilis (6th century AD), forms the basis of most of the world's civil law systems.

The early Roman legal tradition was customary and restricted: the Twelve Tables (450 BC), the earliest Roman legal code, were a written version of customary law published to make it accessible to plebeian Romans who had been subject to arbitrary patrician interpretation. The concept that law should be written and public — not just known to specialist interpreters — was a democratic demand.

The jurists of the classical period (1st–3rd centuries AD) developed Roman law into a sophisticated intellectual discipline. Gaius, Papinian, Ulpian, and Paul worked through abstract principles with considerable analytical precision, developing concepts — the distinction between public and private law, the legal personality of corporations, the doctrine of good faith in contracts, the principle that the accused is innocent until proven guilty — that passed into Western legal tradition.

Justinian's compilation, carried out from 529–534 AD, systematized the accumulated jurisprudence of 1,000 years into the Digest (juristic opinions), the Institutes (a teaching manual), and the Code (imperial legislation). The rediscovery of the Digest in medieval Bologna in the 11th century was the foundation of the academic study of law in Europe and the source of the legal concepts that still govern private law across most of the world.