International economic law seeks to provide rules for international business activities. Nowadays, these activities have to be seen in the light of globalization and the emerging integration of product and service markets all around the world. Questions concerning International economic law are often delicate to handle, given the multiplicity of domestic and international rules that are potentially applicable to concrete cases. The difficulty of identifying appropriate rules and the relation of different legal regimes is, of course, a result of globalization. Complex cases often involve rules of International law (e.g. WTO provisions), rules of regional integration agreements such as NAFTA or MERCOSUR and domestic legislation. These different legal regimes can potentially collide because a guiding meta system is lacking at the moment. Is for example the supranational European competition law applicable to international organizations which might embody a cartel (e.g. to the Organization of Petroleum Exporting Countries – OPEC)? Just this question demonstrates the problems one could have if different legal regimes collided.