Roman law is an essential part of what makes us Europeans. It ought to remain as a foundation of our teaching law - due to the system, and to the lessons it offers in the history of development of law. This paper deals with the beginnings of one of the decisive periods of the evolution of roman law. These periods would be: archaic quiritarian law, edictal law development by magistrates having imperium, and the official development of law in the imperial era. The beginning of the second period was when - in order to alleviate the consuls - the praetor urbanus took over the iurisdictio that was part of the imperium. In this function the praetor ius dicit - informs about the law in force, addicit - establishes the power structure, and dat iudicem - at the request of the parties gives judicial power to third persons to judge their case. These ways the praetor developed the ius privatum, but with the clear aim of serving the utilitas publica, the common good.