More than half the world’s population lives under legal systems derived substantially from Roman law. This is not a figure of speech or a vague cultural influence — it is a specific claim about the transmission of particular legal concepts, doctrines, and analytical frameworks from the Roman jurists of the classical period through Justinian’s sixth-century compilation, through the medieval universities where that compilation was taught, and through the national codifications of the eighteenth and nineteenth centuries that carry Roman legal doctrine in modified form to the present day. The French Civil Code of 1804, the German Civil Code of 1900, the Italian Civil Code of 1942, the Spanish, Portuguese, Dutch, Belgian, Swiss, Japanese, Korean, Brazilian, and hundreds of other civil law codes: all of these are Roman law filtered through historical transmission and adapted to modern conditions.