Today, Europe is in the process of creating a new common law; and to a certain extent this is not a new situation, but rather a return to how things used to be, as for many centuries a ius commune, a common law, dominated Europe. It may even be that future generations, looking back at our times, will see the nineteenth and twentieth centuries as nothing but a temporary interruption in the history of this common law of Europe.
The early Middle Ages:
The Romans excelled at two things: fighting and law making. The crowning achievement of the latter, however, arrived rather late. In the sixth century the Emperor Justinian had a compilation of Roman law made, the Corpus iuris civilis (the body of civil, that is, Roman, law). By then, Germanic tribes had overrun the west of the empire and they preferred their own customary law over the sophisticated Roman law of the Corpus. Likewise, the conquered Roman population had a law which was Roman in origin, but was just as primitive as the law of the Germanic tribes. Very few Germanic customs have been written down, and those that were, above all reveal the poor quality of the law at that time. When around 800 ad Charlemagne ruled an empire which incorporated a large part of western Europe, he tried to bring more legal unity, though without success. After all, the needs of contemporary society were best served by local and customary law.