Like all constituted bodies of government, international organizations change over time—sometimes in profound and unexpected ways. Besides developing through the obvious mechanism of formal amendment by the constituent member states, these governance bodies can and do undergo a more autonomous kind of constitutional development—what might be called informal constitutional change or transformation. This type of quiet evolution may occur on different levels—including the reordering of the organization’s internal architecture in terms of the relative competences of its various organs, as well as the development of the powers of the organization as a whole vis-à-vis the states parties. Unlike formal amendment, which occurs through the express decision of the member states according to a certain procedure, informal transformation occurs more subtly, through the practice of the organization. Although the latter mode of change may attract less attention than the former, the degree of change involved can be just as dramatic.
This Article is about one particular mode of informal change: the transformation of an organization through the practice of its judicial organ in the interpretation of its constituent instrument—in other words, transformation through constitutional interpretation. Not all international organizations include judicial organs, and not all judicial organs are constituted in the same way. Different institutions have been delegated different powers and different kinds of jurisdiction. Their judges are chosen through widely varying procedures, and entertain very different interpretive outlooks. Yet in the abstract the basic fact remains clear: where they are established, such international courts and tribunals tend to contribute substantially to the development of their larger organizations. Through the interpretation of the formal terms of their constituent instruments, these constituted judicial bodies have proven capable of transforming the material constitutions of the organizations to which they belong.