In procedural law, the role that the judge must play in the trial is discussed. On the one hand, an active judge; on the other, a guarantor judge who leaves the leading role to the parties, considering that in this way equality and impartiality materialize. For this reason, it was formulated as a research problem: What is the procedural system and the concept of purpose of the process that defines the role of the judge in the Colombian contentious-administrative process? It is proposed to analyze, from within the procedural institutions, the charges and duties of the judge and the parties, based on the hypothesis that there are no boundaries that allow the precise definition of the nature of the procedural system and the concept of purpose of the process to which the judge must attend to exercise his function. To this end, an exploratory-analytical study of the applicable standards was carried out. The result of such analysis is that the role of the judge in the contentious-administrative process is not defined by the procedural system or the concepts of the purpose of the process, but is due to the legal nature of the claim or means of control. © 2023 Fundacao Getulio Vargas, Escola de Direito de Sao Paulo. All rights reserved.