International law lacks the kind of comprehensive framework to organize and structure its rules, institutions and functions as is provided for in nation states by their constitutional foundations. Instead, the international legal system, at least as far as treaties are concerned, can largely be seen as an ensemble of separate regimes which are equal in rank and distinct in membership, rules, institutions, lawmaking mechanisms and dispute settlement. Their interrelationship is governed by two rather different means: at one side, some political oversight may be exercised by international organizations within a number of confines and limits. At the other side, if it comes to questions of the application and interpretation of particular rules in particular cases, the international law of treaties, as mainly provided for by the Vienna Convention on the Law of Treaties 1969 (VCLT), comes into play.