Strictly defined, the term "Roman Law" refers to the legal system of ancient Rome, and its development from the founding of the city in the 753 BCE through the fall of the Western empire in 476 CE. The texts preserving this tradition begin with the Twelve Tables (c. 449 BCE) and end with the Corpus iuris civilis (529-534 CE). From a practical perspective, the term "Roman Law" also refers to the legal system of Western Europe through the early modern period. Modern civil law is a direct descendent of this system.

Portions of the Corpus iuris civilis remained in use through the early middle ages in one form or another, but the reintroduction of Roman Law in Western Europe dates to the late eleventh century, and coincides with the rise of the university and law schools. A new familiarity with Roman Law provided an opportunity to consolidate and refine the law to meet contemporary needs, and modern Civil legal systems owe much to medieval and early modern legal scholarship. For a period of several hundred years, the study of and reliance on Roman Law provided a sense of commonality for Civil Law countries.