The present research aims to address the system of judicial precedents and its applicability in the judicial system and its effectiveness in a judicial decision, with the light of the analysis of legal reasoning. In the current times the stare decisis has been introduced gradually in the system of civil procedures, it gives by approximation of the tradition common law to civil law . It is a doctrine with nuances that require the operator to some techniques needed for your application. Then, more and more importance has been added in this judicial precedents, but must be care to handle it, cos it can't be ignored the facts around it : The fundamental rights, constitutional norms and the Rule of Law and the arbitrariness of the state, for bot...