What's called "Roman law" in Europe derives from the Justinian Code, which was nominally a codification of but in many respects a radical reinterpretation of late roman law. Prior to the Justinian Code, and especially Scholastic era glosses, Roman law was arguably more like a very rigid style of common law; that is, requiring judges to hew closely to precedent rather than applying abstract legal principles.

It was the rediscovery of the Justinian Code during the Scholastic age which kickstarted a blossoming of legal theory in Europe. But they didn't understand that the Justinian Code wasn't a reflection of Roman law so much as a reflection of Emperor Justinian's reforms, which were in part an attempt to reassert control over and simplify the legal system.