Customary International Law: The Source of Substantive Rules in the Framework of the International Criminal Court

Contrary to the Statutes of the International Criminal Tribunals for the Former Yugoslavia and Rwanda, which specify only the jurisdiction of those tribunals and the Applicable Law should be sought elsewhere, Article 21 of the Rome Statute sets out the applicable law by the International Criminal Court (ICC). A noteworthy point in Article 21 is that there is no explicit reference to Customary International Law as a legal source applicable by the International Criminal Court. Then some consider this silence to be an end to the role of Custom as a legal source in the ICC's setting and International Criminal Law in general.On the other hand, some still believe that the ICC can invoke Customary International Law as a substantive source of law. This article, after referring to the practices of other International Criminal Tribunals and expressing opposing and agreeing views in International Criminal Law, finally shows that in special cases, invoking custom is the only way to exercise criminal jurisdiction over certain crimes and establish Individual Criminal Responsibility within the framework of the Statute of the International Criminal Court.