"Invention” of the Custom or Only a “Transformation” in The Way of Recognition? (Resort to Uncertain custom in International criminal law)

The traditional way for recognizing of international customary law by an international court was based on finding out two factors: the »state practice« as well as opinio juris. Nowadays this traditional way is changed by international courts and these courts do not consider »state practice« as a main factor for recognition of international customary international law. Jurists opponent to this approach mention that using this way is illegal and can be regarded as “inventing customary international law by a court” and therefore is beyond the delineation of the judges duties. On the other hand, the advocators express this approach as an evolution in international law so that a court can find out an international customary law without paying too much attention to »state practices «.
In international criminal law, using of the traditional way for recognizing the International customary law does not take place, especially in some tribunals such as ICTY because of security council resolutions.
In addition, some international criminal tribunals have also diminished their resort to “state practice” for recognizing international customary law by considering “Martens clause”, “Human rights” and even decisions of political bodies of international organizations instead of using state practice. This approach has been used in second generation of international criminal tribunals for many times.