This study aims to analyze the constitutionality of the current regime of provisional protection of unavailability of assets, sanctioned in the Brazilian legal system by Law n. 14,230/2021. The methodology used in the investigation was descriptive-exploratory, with emphasis on the analysis of the legal arguments built over the last 20 years by doctrine and jurisprudence. Firstly, the contours of administrative impropriety in the national order and the jurisprudential, doctrinal and legal aspects related to the precautionary measure of unavailability of assets in actions of improbity were presented. Next, the essential characteristics of precautionary measures within the scope of Civil and Criminal Procedure were discussed, which contributed to the analysis of the constitutionality of the current regime of provisional protection of unavailability of assets. Finally, in the last topic, an analysis was made of the constitutionality of the new regime of provisional protection of unavailability of assets in actions of administrative improbity, concluding that the new legal device, which demands the presence of the double requirement of precautionary measures (fumus boni iuris and periculum in mora), is the one that best conforms to the legal principles in force in the Brazilian normative system.