twofold process which also includes a parallel institutional development in addition to the verticalization of law. One needs to think only of whether or not it is possible to achieve a common and universal goal by means of an horizontal structure? Horizontal societies are not able to stabilize power. Coercion and coaction function much more effectively within a vertical structure, as demonstrated in domestic systems. We must therefore bear in mind that constitutionalization means two things. First, that there is a hierarchy of norms within international law, not only from a formal point of view, in terms of a hierarchy among the sources of international law, but also from a material point of view, in terms of the substantive content of norms. Second, there is a growing tendency to view the hierarchical structure of law as a positive, unifying factor. An hierarchical structure encompasses the individual, the state, and the international community, thus acknowledging the existence of a global or universal society. In this way, it is superior in rank to any other kind of norm, be that global, regional, or domestic. The acceptance and recognition of certain universal values means necessarily that there is at least a minimum shared content to any juridical construct with authority in the area of rights and obligations. The justification and juridical content of these universal values can be found only at a very high level of abstraction. This overriding idea of justice must, from a legal perspective, try to harmonize the justice of the decision according to positive law, with the justice of the decision according to meta-juridical notions. The question of how to identify these rules is one task of the participant in the process of law formation. The legal practitioner is thus responsible for readjusting legislation so as to make and shape the law. This does not means that it is exclusively a task of the legislative; rather, it is the task of all decision-makers.
unlimited.491 Formally, the debate addresses the process of the elaboration and application of international norms, on the one hand and, on the other, of internal law.492 The polemic stresses the respective unity, duality, or plurality of legal orders. The two opposing doctrines regarding the relationship between internal and international law are the dualist and monist schools of thought. For the dualists, there exist two coexisting independent systems, totally separate from one another. The efficacy of international law within the system of domestic law is not direct; rather, international law is adapted and transformed into national law. Thus, each reigns supreme in its own sphere.
Contemporary doctrine refers to the existence not only of two legal systems, but rather to a plurality of them, as many as there are institutions. On the other side, the monists contend that international law is directly applicable within a system of domestic law;
their relationship is basically one of interpenetration. According to this theory, both schemes belong to a unique system that is grounded in the identity of subjects (individuals), and the identity of sources (the existence of an objective foundation and not procedures). 493
The general doctrinal trend has seen a progressive development, from the law of coordination to a law of subordination that favours the hierarchical structure of the international legal system, as demonstrated by increasing institutionalization. On the one hand, dualists do not pay much attention to the question of a hierarchy of norms within international law. On the other, those who admit the existence of a unique system assure the primacy of international law. In spite of all these debates, scholars generally agree with the principle of the primacy of international law. Accordingly, the principle of the primacy of international law is regarded as the starting point in their conception of an all-embracing legal system. Such a thinking becomes possible when states are considered not to possess sovereignty in an absolute sense. Sovereign collectives acting within a universe of legal structures thus depend on the existence of a superior law; this superior law is international law.494 The International Court of Justice has recalled in its Advisory Opinion of 26 April 1988, that "the fundamental principle of international law
491 Kelsen, above note 406, p. 300.
492 Dailler et al, above note 403, p. 105.
493 Ibid., p. 107.
494 Ibid., p. 105. According to them this example correspond with te monists view of the relationship between national and international law represented by the Vienna School (Kelsen, Verdross, Kunz). also Scelle
that international law prevails over national".495 However, the extent of the supremacy of international over national law on the international plane remains an open question.496
There is no hierarchy under the classical horizontal dogma of international law.
Municipal law systems contain a hierarchical structure that "reflect[s] the will of people to make some legal commands more important and stronger than others, for they reflect values shared by the overwhelming majority of citizens."497 Although this is an undeniable truth for western democratic and constitutional societies, classic international law with its horizontal structure, in fact recognizes no hierarchy of sources or rules. Similarly, international law was first conceived of as a law of coexisting entities, without any limits imposed upon the sovereign powers of states; it was quite unlike a domestic system where laws are subject to a vertical structure of subordination.498 Furthermore, international law has been traditionally conceived of as contractual law born from state consent. It is a law whose sources are all placed at an equal level. The result of this lack of hierarchy was that the relationship among international rules derived from the same source came to be governed by the principles of conflicts of rules like lex posteriori derogat anteriori and lex speciali derogat generali.499
1 Examples
Today, the panorama is entirely different. At present, new conditions have brought into existence a special class of general rules that enjoy a special legal force. The principal category of rules is the so-called ius cogens; these are said to have a peremptory nature.500 Another important category of superior norms are the obligations erga omnes, owed to the international community as a whole. Obligations erga omnes are said to be
"virtually coexistensive"501 with obligations of ius cogens. In addition, these new developments have brought some scholars to plead in favour of giving erga omnes
495 Applicability of the Obligation to Arbitrate under Section 21 of the United Nations Headquarters Agreement of 26 June 1947 Advisory Opinion of 26 April 1988, ICJ Reports 1988, p. 12, at p. 34 para.
57.
496 Buergenthal & Murphy, above note 407, p. 7.
497 Cassese, above note 430, p. 198.
498 Pauwelyn, above note 437, p. 94.
499 Gilbert Guillaume, “Jus cogens et Souveraineté” in L’Etat Souverain dans le monde d’aujourd’hui.
Mélanges an l’honneur de J.-P. Puissochet, 2008, p. 127.
500 Cassese, ibid., p. 199.
501 Pauwelyn, ibid., p. 100.
effects to the so-called public interest norms.502 Another example of potentially superior norms are the obligations under the UN Charter.503 Article 103 of the UN Charter states that, "[I]n the event of a conflict between the obligations of the Members of the United Nations under the present Charter and their obligations under any other international agreement, their obligations under the present Charter shall prevail." Furthermore, binding obligations with moral or constitutional content, such as the prohibition of slavery, have been developed successfully within the context of international law.
Universal criminal law is another field where the fundamental rules in international law are developing fast. In our contemporary world, international law is far from being a set of norms jumbled together in an uncoordinated assemblage of rules that loosely belong to a fragmentary system. For this reason, we can affirm that international law recognizes and accepts the existence of such fundamental rules of the international legal order as ius cogens norms, and erga omnes obligations. Interestingly, from a legal perspective the distinctive criterion of all these rules is their legal consequences. Their common factor is the essential need for urgent realization of those values protected by the rule. 504