Unlawful detention constitutes a violation of fundamental individual freedoms and differs from the detention of innocent individuals; unlawful detention involves a clear breach of laws and regulations, whereas the detention of innocent persons typically results from errors or insufficient evidence. This study aims to comparatively examine the conditions and cases of unlawful detention in the legal systems of Iran, the United States, and France, and to analyze the protective mechanisms in each country. The research employs a descriptive-analytical method, focusing on legal provisions including Article 57 of the Iranian Code of Criminal Procedure and Article 32 of the Constitution of Iran, the Fourth and Fourteenth Amendments of the U.S. Constitution and the right to a judicial review for release from unlawful detention, as well as Articles 6 and 7 of the European Convention on Human Rights and Articles 144 to 147 of the French Penal Code. The findings indicate that in Iran, restrictions on detention without judicial order and the establishment of legal conditions have significantly reduced the occurrence of unlawful detention, though ambiguities remain in protecting citizens against the detention of innocent individuals due to insufficient evidence. In the United States, judicial oversight and the right to judicial review provide an effective protective framework, while in France, the combination of domestic regulations and the European Convention guarantees lawful detention and the possibility of compensation. The study concludes that establishing effective legal and criminal safeguards against unlawful detention in Iran,