Some of the international treaties have been concluded in order to harmonize the procedures of countries in adopting the desired criminal policy in Combating threats that target public order beyond a specific country. Due to the principle of legality, the national implementation of such treaties with penal provisions is fraught with challenges.
In the present article, it is determined by a descriptive analytical method that these treaties are the source of legislation in most systems, although in Muslim countries with a legal system based on Islamic law, the Shari'a standards do not allow their acceptance. If the treaty passed by the parliament is self-executing, it will not be a problem for the national courts to recognize it as valid, although the implementation of the provisions of the treaties, especially in the criminal dimension, often requires the enactment of a supplementary Act. The interpretation of these regulations is within the Jurisdiction of the national judge, and in case of conflict, different solutions have been offered according to the approach of the legal system, Which is Affected by the position of treaties in the hierarchy of internal regulations and the approach to the theory of unity or duality. The rules of criminal law also do not allow the retroactivity of these provisions, However, in some countries this rule has been violated.