Under the conditions of legitimization of the constitutional process, constitutional subjects seek to improve the method of decision-making and privilege a certain type of argumentation. Although there are many tools to achieve this, the purpose of this contribution is limited to the study of evidence as a tool of legitimation. On the one hand, legal evidence, as it is an irreplaceable means of achieving a certain truth, and on the other hand, it is legitimized, as it involves an evidentiary procedure that guarantees the right of each participant in the legal process to have his case heard by a judge. If the evidentiary regime, whose function is to demonstrate the truth of the facts, is sometimes a pole apart from that which has the function of obtaining community approval, these two functions contribute to the same goal of legitimizing the constitutional process. Evidential legitimation does not correspond to a natural process, but rather consists of a discourse that treats the evidence in certain ways, or rather in different ways, in order to increase the legitimacy of the constitutional judge's decisions. If it falls under the specific field of comparative constitutional jurisprudence, the contribution appeals to the context of the general theory of evidence and, in particular, to the recently conceptualized functions of evidence. It follows from this that in the process of depoliticization or jurisdictionalization of the review of constitutionality, constitutional subjects strive, on the one hand, to improve the way of decision-making, and on the other hand, to privilege a certain type of argumentation. Although there are many tools to achieve this, the purpose of this contribution is limited to the study of evidence as a tool of legitimation. More specifically, the process of legitimization by evidence can be conceived as a process initiated by legal entities in order to gain authority among different audiences. The main function of evidence is to verify the production of facts that are decisive for the resolution of the dispute and to which the law attributes legal consequences. This function of proof consists in determining the truth of statements that describe the occurrence of these defining facts. However, it is important to note that this contribution is not intended to position itself on the content of the truth in the judicial process.