Laws on Walls between the Rabbis and Rome

The Roman Empire left many things to the West, from marble columns to an ineffectual Senate, the names of days and months, and a certain martial ideal of masculinity. Perhaps the most important imperial export, and one of pointed import for the birth of Judaism, was the law. Roman law was a marvel, and Rome was committed to both the fact and the idea of legal justice as a central component of their successful ruling strategy. But in a world lit only by fire, how did people get their laws?