This article will survey the new non-traditional scholarship which has emerged in international law to challenge the two long-established
sources of customary norms, state practice and opinio juris. With the recent growth, in the international system, of self-contained international criminal tribunals, new challenges
facing international law have emerged. Institutionally structured as self-contained legal regimes, international legal tribunals
such as the ICTY, ICTR, and now the ICC have nevertheless contributed to a new paradigm within international law. The jurisprudence
of these international criminal tribunals, on a wide range of international legal questions, has slowly begun to be elevated
into norms of customary international law. Given this fact then, the debate over whether consistent state practice and opinio juris are the only building blocks of customary international law is over, because clearly, for better or for worse, they no longer
are. The new question, the new debate, will be over what the implications of this shift in the traditional building blocks
of customary international law are, not only on the international system as a whole, but also, surprisingly perhaps, on national
(domestic nation state) legal systems as well. The domestic law angle is key, for in the past few years the jurisprudence
of these international tribunals has, aside from finding its way into customary international law, also begun to seep into
the domestic (mainly criminal) law of several countries.