Merriam-Webster Collegiate Dictionary - roman law

 noun  Usage: often capitalized R  Date: 1639 the legal system of the ancient Romans that includes written and unwritten law, is based on the traditional law and the legislation of the city of Rome, and in form comprises legislation of the assemblies, resolves of the senate, enactments of the emperors, edicts of the praetors, writings of the jurisconsults, and the codes of the later emperors