This work examines how the classical Roman jurists solved the problem of the justification of their decisions. Thus, it shows their usual silence and the scarce references to dogmatic and non-dogmatic fundaments; all this, in special connection with the concept of Strict Liability. From here on, the research is carried out with diachronic and synchronic elements, exposing the different modern doctrines on the fundament of this liability to judge its possible adequacy to the cases presented in classical Roman Law. The foregoing allows us to conclude that there is no single basis in classical Roman law for all the hypotheses of Strict Liability; however, those that have been identified can be grouped under two categories: economic and material fundaments.