RESEARCH OBJECTIVE: A brief exposition is presented on the origins and developments of Roman Law, taking as starting point the idea of a Law of Jurists that becomes a Law of Autocrats (the emperors), with changes in the sources and in the sustenance of the same ones. The ultimate result is the codification of that Roman Law in the times of Justinian and the ancient (not modern) meaning of the notion of Code. THE RESEARCH PROBLEM AND METHODS: It is a purely informative, synthesis and exposition work for which it has relied on the most recent and the most traditional bibliography and sources, analyzing one and the others. RESEARCH RESULTS: The two great moments (classical and postclassical) of the Roman era are presented, from the legal perspective, to show how this slow and painless transition from an open and plural system to another monotone, dominated by the emperor in both what the new Law refers to as old Law. The Code is the final recapitulation of this Roman intellectual and cultural world. CONCLUSIONS, INNOVATIONS, AND RECOMMENDATIONS: Rome manages to evolve, without betraying itself and without abandoning its oldest sources; rather, assembling all the materials and creating a method in which medieval and modern jurists will then be inspired. In the final Code and Codification they manage to incorporate all that Law and the main guidelines for its interpretation. [ABSTRACT FROM AUTHOR]