The present work aims to create in students and scholars of the Law an interest in the study, knowledge and deepening of the Forensic Sciences, derived from the importance they have and the contribution they make within the Justice System, as a necessary complement to the set of legal norms that make up the system. It also seeks to warn Judges, Magistrates, Prosecutors, Defenders and other participants in the Justice System, especially in the criminal field, about the risks that an overestimation and blind credibility of the expert evidence can produce; relegating the jurisdictional function and turning the experts into decision-makers of the cases, which is legally incorrect and even dangerous.