In this chapter, the influence of Hellenistic philosophy on Roman law is discussed in terms of method: with the help of the Stoic dialectical methods of classifying and defining the Roman jurists could start to systematise the organically grown output of their civil law and turn the resolution of disputes into a scientific enterprise, producing systematic overviews along the way. In the 6th century CE, the Roman Emperor Justinian took the influential decision that an updated version of one of these accounts itself be given the status of law.