The fragmentation of the international social world has attained legal significance especially as it has been accompanied by the emergence of specialized and (relatively) autonomous rules or rule-complexes, legal institutions and spheres of legal practice. What once appeared to be governed by ‘general international law’ has become the field of operation for such specialist systems […] each of them possessing their own principles and institutions. The problem, as lawyers have seen it, is that specialised law-making and institution building tends to take place with relative ignorance of legislative and institutional activities in the adjoining fields and of the general principles and practices of international law. 1