Jurisprudence was defined differently by the Roman jurists who lived in the period of antiquity because the etymology of the word designates the "science of law" which included the legal phenomenon. This fact is contemplated by the definition that Justinian inserted in his legislative work: «Juris prudentia est divanarum atque humanarum rerum notitia, iusti atque injusti scientia» (Jurisprudence is the knowledge of divine and human facts, the science of what is just and unjust ) Over time, jurisprudence has moved away from this explanation and has attributed a truly different meaning to jurisprudence as a set of legal rules born from judicial activity. At the same time, the new definition of jurisprudence has introduced one of the main differences between the main legal systems. Consequently, on the one hand the family of Roman-Germanic law believes that "the judge is the mouth that speaks of the law", that is to say that he only has the competence to interpret the law, on the other there is the Anglo-Saxon family governed by "judge made law" principle. The reason for the existence of limits on the power of the judge in the French legislative system is to be found in the Enlightenment movement that sparked the spirit of the French Revolution. This reason consists in the idea that the judge is the representative of the king and the noble category who is not concerned with the Internet in general, but with maintaining the privileges of the aristocracy. The revolt against judges was so powerful that Robespierre believed that "the word jurisprudence of the courts should be erased from our language." becomes part of the community legal system. Consequently, decisions rendered by European courts contribute to the development of domestic law jurisprudence. However, the jurisprudence of the Court of Justice is substantially different from that which comes from national courts because they issue decisions that have only relative authority, i.e. that it applies to the case to be resolved and between the parties in the ongoing trial. On the contrary, the decisions of the Court of Justice are imposed into domestic law having legal force and therefore the jurisprudence of the Court of Justice becomes a source of law. From this derives the paradoxical character of jurisprudence: it is a source of law when it is the result of the judicial activity carried out by the European Court of Justice, but not when it is a national jurisdiction..