Everything is complicated, but everything is complicated in different ways. The international law of migration has a ready claim to distinctive complexity along at least two dimensions.
First, it is surely the most important area of international interaction lacking a formal multilateral institutional framework. There is no International Convention on Migration or World Migration Organization. Instead, an awkward agglomeration of mostly bottom-up processes, initiatives, piecemeal conventions, and United Nations agencies is emerging to grapple with the challenge of unprecedented movements of persons across national borders.
Second, migration has traditionally and exceptionally been located at the core of sovereign discretion. The conventional wisdom still holds that states are largely unconstrained in exercising preferences with respect to the admission of aliens and the terms thereof.
These two distinctive features have been mutually reinforcing. The insulation of migration practices from international law has retarded the development of a centralized institutional apparatus, and the lack of that apparatus impedes doctrinal footholds from which to expand international law's reach into the area.
Even in the absence of an umbrella regime, however, there is evidence that international law is insinuating itself into state migration practice. Migration can hardly be insulated from...