Good governance is achieved based on specific indicators, among which the existence of lawful and just legal frameworks is of utmost importance. Accordingly, all citizens are subject to the law and accountable for their actions. One of the laws that guide societies toward good governance is criminal law. Among criminal law provisions, determining the minimum age of criminal responsibility is a particularly crucial issue that requires a clear, explicit, and just statute. In this thematic domain, a comparative study of the laws of two countries reveals how criminal legislation contributes to the realization of good governance. The determination of the minimum age of criminal responsibility in the criminal law systems of Iran and England, which are selected here as case studies, is examined in comparison with international instruments, which serve as models for standardizing juvenile criminal justice. This standard varies across societies and individuals due to factors such as climate, race, and socio-environmental conditions. Such diversity in the criteria for establishing criminal responsibility among children has hindered the formation of a unified legal approach in different societies regarding a specific age threshold. Hence, various international instruments recommend that member states determine a "minimum" age of criminal responsibility and adopt a gradual responsibility system in dealing with children and juveniles in conflict with the law. Clearly defined age thresholds for criminal responsibility can serve as indicators of good legislative governance. In this regard, the primary question of this research is: How do the criminal law systems of Iran and England, in determining the age of criminal responsibility, affect the process of achieving good governance? It appears that the legal systems of both countries have undergone numerous legislative reforms and to some extent align with international instruments and standards. In Iranian Islamic Penal Code, this is reflected in the distinction between the "age of puberty (bulūgh) for criminal liability," "age of criminal responsibility," and the classification of crimes into those requiring ḥadd or qiṣāṣ punishments and those resulting in ta‘zīr penalties. This study utilizes data analysis to explain the role of criminal law in Iran and England and its impact on good governance. Findings indicate that the minimum age of criminal responsibility in international instruments and in the United Kingdom is 18 full years, and individuals under 18 are considered children. In Iran, the age of puberty is 9 lunar years for girls and 15 lunar years for boys. Nevertheless, regarding criminal responsibility, if an individual under 18 commits a crime punishable by death, such a person shall not be executed; the execution is to be deferred until reaching the legal age. Criminal laws aligned with the principles of good governance contribute to enhancing the political legitimacy of the system and increasing public satisfaction. Promulgating such laws raises public awareness about their rights and duties and thereby promotes sustainable human development.