The concept of "dangerous state" (or dangerousness) is a contentious issue in criminal law and criminology, as its assessment involves predicting future behavior and may serve as the basis for measures that restrict individual liberty. The central challenge lies in balancing the necessity of crime prevention with the protection of individual rights and freedoms, ensuring that the mere likelihood of committing a crime does not replace the requirement to prove the commission of an offense or become an independent basis for unfettered state intervention. Employing a descriptive-analytical method and a comparative approach, this article examines the concept of dangerousness and its legal manifestations in the United States, France, and Iran. In U.S. law, pretrial detention and civil commitment under specific statutes exemplify interventions based on risk assessment. In France, Law No. 2008-174 of February 25, 2008, establishes a mechanism for "security detention" (*rétention de sûreté*) subject to strict legal conditions. In Iran, Article 150 of the Islamic Penal Code (2013) is significant, addressing specific situations involving insanity arising after the commission of a crime and the detention of the individual in compliance with legal requirements. Research findings indicate that these examples differ in their underlying rationales, objectives, and conditions of application, and thus cannot be regarded as instances of a single, unified legal institution. Despite these differences, the necessity of a clear legal basis, individualized and reasoned assessment, adherence to the principle of proportionality, and the availability of oversight and judicial review constitute fundamental criteria for the legitimacy of liberty-restricting measures based on future risk.