The nature and status of criminal maturity in the Iranian legal system has long been one of the most contentious issues, especially after the enactment of Article 91 of the Islamic Penal Code in 2013, which triggered widespread debate.  This article aims to clarify the relatively new approach of the legislator by describing and analysing scholarly sources and closely examining the Islamic jurisprudential foundations on which Article 91 is based.  The research concludes that, under Article 91, the legislator regards attainment of puberty merely as a rebuttable presumption of criminal maturity; there is no necessary connection between the two concepts. What truly matters is proof of discernment and understanding as the foundation of criminal responsibility, not simply reaching the age of puberty.  Another finding of the study is that, according to scientific sources, legislative materials, and international instruments, there is serious doubt about the criminal maturity of individuals who have reached puberty but are under 18 years of age. Therefore, pursuant to Article 91, hudud and qisas punishments—just like full ta’zir punishments—are lifted from such persons. They will instead be sentenced to security and corrective measures or punishments of a similar nature in these offences, unless the complete mental maturity of the accused is conclusively established by experts relying on scientific evidence.