Roman law is the legal system of ancient Rome, and the legal developments comprising more than a thousand years of jurisprudence from the Twelve Tables (c. 439 BC) to the Corpus Juris Civilis (AD 529) ordered by the emperor Justinian I. The historical importance of Roman law is reflected by the continued use of Latin legal terminology in legal systems influenced by it.
The Twelve Tables and the Corpus Juris Civilis - Subpoena, habeas corpus, pro bono, affidavit—all these terms derive from the Roman legal system, which dominated Western law and government for centuries.
Justinian I was a Byzantine emperor from 527-565. During his reign, Justinian sought to revive the empire's power by reconquering the lost western half of the historical Roman Empire. 1 of the most important figures of late antiquity & possibly the last Roman emperor to speak Latin as a first language, Justinian's rule constitutes a distinct epoch in the history of the early Middle Ages. The impact of his administration extended far beyond the boundaries of his time & domain.
Fascinating click-through article: "10 Innovations That Built Ancient Rome" -- Shown: "Bound books: Romans streamlined the medium by creating the codex, a stack of bound pages that is recognized as the earliest incarnation of the book"