Ignorance of the law is among the concepts whose exculpatory effect on criminal liability has long been a subject of debate among criminal law scholars. The presumption of inadmissibility of claims of ignorance of the law (ignorantia juris) or the inexcusability of legal ignorance has historically held considerable certainty. However, an absolute application of this presumption may lead to unjust consequences, thereby undermining criminal justice. The assumption of the impossibility or inability to become aware of the law raises the question of how the criminal justice system should address negligence in cases of legal ignorance. Answering this question requires an examination of the criminal legislator’s stance toward this type of ignorance. Imami jurists have also distinguished between negligent ignorance (jahil-e qasiri) and culpable ignorance (jahil-e muqassir) in assessing the permissibility of punishing an ignorant individual, prescribing distinct rulings and consequences for each. This distinction highlights the necessity of differentiating between various types of ignorance and further examining the assumption of the impossibility of legal awareness. Accordingly, this study employs a descriptive-analytical method to examine criminal negligence in jurisprudence and Iranian criminal law, aiming to provide a relatively comprehensive answer to the question of the status of negligence and its effects on criminal liability. The conclusion is that the Islamic Penal Code of 2013 (Article 155), for the first time, has recognized excusable ignorance (jahil-e qasiri) as an exception to the presumption of inadmissibility of claims of ignorance of the law, in line with the prevailing opinion among Imami jurists who exclude such ignorance from the scope of liability. Thus, criminal negligence is considered one of the grounds for excluding criminal liability.