The Scope of Mental Disorder Defense in the Criminal Systems of Iran and the United States of America

One issue that can challenge the criminal justice system is the claim of mental disorder at the time of committing a crime. Acceptance of this defense reduces the punishment or leads to the acquittal of the accused. Mental disorders encompass a wide range of brain disorders, with the most severe being insanity, which is recognized as a factor that removes criminal responsibility in various legal systems, including those of Iran and the United States of America. Therefore, if a person commits a criminal act but lacks the necessary capacity to discern the rightness or wrongness of their actions, the attribution of responsibility to the perpetrator is lost, and they will not be held accountable. Article 149 of the Islamic Penal Code of 1392 states, "If the perpetrator is mentally disturbed at the time of committing the crime in such a way that they lack volition or discernment, they are considered insane." In American law, the concept of insanity is rooted in common law, and regulations governing insanity differ across different states in the country. American legal professionals believe that mentally ill individuals who commit crimes should undergo psychiatric treatment before facing punishment. At the same time, the legal rights of these mentally ill criminals must be respected, but concerns about public safety and preventing the frequent dangers posed by these individuals must also be taken into account. The goal is to strike a balance between the patient's right to treatment and the responsibility to ensure public safety.
This study aims to explain the concept of insanity, the conditions required for its verification, and its effects on the criminal justice systems of America, Iran, and Imami jurisprudence. It seeks to answer the following questions: What are the conditions to prove insanity in the legal systems of Iran and America? What is the stance on diminished responsibility in the criminal justice systems of Iran and America? Are milder mental disorders than insanity also recognized as an obstacle to criminal liability?
Methodology: This study employs a descriptive-analytical method and relies on a library collection tool.
Discussion and Conclusion: The principle of acquitting individuals with insanity from criminal liability is generally accepted in Imami jurisprudence and the criminal laws of Iran and America. Jurists consider it necessary for a person to possess the legal capacity to be held responsible, and the general conditions of religious obligation form the basis of criminal responsibility and the legitimacy of imposing any type of punishment that society implements on a criminal for committing a crime. Insanity has an impact on criminal liability in the laws of Iran and America. Article 149 of the Islamic Penal Code, approved in 2012 and based on the McNaghten criteria and the Model Penal Code, establishes that mental disorders leading to a decline in volition or discernment remove criminal responsibility. Criminal responsibility or non-responsibility is absolute in the Islamic Penal Code. Consequently, many individuals with mental disorders are deemed fully criminally responsible. The need to consider diminished responsibility in the context of insanity rules is evident and requires attention and revision to ensure fairness. Recognizing this necessitates focusing on two aspects related to the issue of insanity: the legal aspect and the psychiatric aspect. Psychiatry has shown that there are intermediate states between sanity and insanity that do not lead to a deterioration of criminal responsibility like insanity, yet the accused does not possess complete mental and psychological health to be considered responsible for their actions.
Diminished responsibility comes into play when an act has been committed, and the law prescribes punishment for the act, but due to specific circumstances, the primary punishment cannot be applied, and a lighter punishment is imposed instead. In the United States, the "guilty but mentally ill" act has recognized diminished responsibility since 1957. In cases where the perpetrator exhibits impaired discernment or volition but does not lack them entirely, they are considered guilty but mentally ill, and a reduced sentence and rehabilitation are taken into account. The purpose of this law is to both remove dangerous individuals from society and provide treatment for mentally ill individuals. This means that mentally ill patients who have not reached the point of insanity are not sentenced to the original punishment for the crime committed but rather receive a lesser degree of punishment. In American law, according to the McNaughten rule and the Model Penal Code, if mental retardation leads to a decline in discernment, the person is not held criminally responsible. The Eighth Amendment of the United States Constitution considers the death penalty for mentally retarded individuals as an unjust punishment, but lighter punishments are applied to such individuals. In Iranian law, Article 38 of the Islamic Penal Code includes illness as a mitigating circumstance. However, when the defendant's illness is not deemed effective in committing the crime, the judge has the power to reduce the punishment based on the clarity and combination of the two aforementioned articles.