But why Iran and why France? And why should we study the case of the latter? Since the entry into force of the great codifications of criminal law in the 20th century, jurists have had recourse to comparative law to improve their respective national laws and to fill in the gaps in their national codes, considering that, since the end of the 20th century, in the legal sciences, there has been increasing talk of globalization and harmonization of criminal law. In addition, it allows the jurist to have a better knowledge and understanding of his or her own law, whose particular characteristics become clearer in view of a comparison with other countries. In order to avoid focusing only on the Western world, we have conducted comparative research with Iran in order to better understand the processes of regionalization, the importance of which had been revealed by the research involving the situation of an Asian country. The Iranian criminal justice system was inspired by the functioning and guiding principles of the French criminal justice system and criminal procedure, based on the views of French jurists.