Introduction: One of the cases of intentional crimes in the Islamic Penal Code is typically lethal behavior which the exact criteria have not been explained for its identification. Failure to provide identification criteria in practice has led judges to try to use the views of forensic experts to assess the perpetrator's behavior, as the case may be. Despite the efforts made, we have in some cases been confronted with different opinions and perceptions and subsequently with the issuance of some dissenting opinions in the courts. Therefore the aim of this study was to investigate the dimentions of typically lethal behavior and explanation of effective components in its identification and the position of forensic medicine expert in this field. The present review study is a descriptive study conducted through the library study of some legal and medical sources, especially the branch of forensic medicine and important notes were taken and a number of cases referred to forensic medicine were examined.
Conclusion: The two main components that are the main focus of forensic medical expertise in this field are the sensitivity of the site of impact and the characteristics of the injury. Determining typically lethal behavior is a matter for the judiciary. Therefore, forensic experts cannot be legally required to specify phrases such as "typically lethal behavior. Comments of forensic experts on the lethality of injuries is as Special custom. The judge must finally makes decision according to customary standards regarding the typically lethal behavior, and issue an appropriate sentence verdict based on legal conditions and other requirements such as knowledge, awareness and attention of the offender to the typically lethal behavior.