First of all: thanks for the thoughtful comments by Daniel Bodansky, and Jeffrey Dunoff and Joel Trachtmann. As I read them, they are not rejecting constitutionalization as a useful approach to the study of international law. This does not, however, mean that they subscribe to everything that is said in The Constitutionalization of International Law. I will take up some of their main concerns and objections – which does not commit my co-authors.
I have emphasized the public law character of international constitutionalization, i.e. that empowered international institutions should be under constitutional control, in the form of democratic guarantees, rule of law, and protection of human rights. Our book is a thought experiment in asking how a constitutionalized world could look like. There is an underlying assumption that the world is becoming more constitutionalized. But the book does not represent an empirical study of this process and its causes. It is more concerned with the normative issues: what kind of constitutional guarantees should balance the increasing empowerment of international institutions?
This does not mean that we are fully occupied with enjoying the Lotus garden at the expense of hard work, as Dunoff and Trachtman suggest. First, the development of a constitutional perspective and its possible consequences represent in itself hard work. This is what we have tried to do in the book. But, second, although we have not undertaken an empirical study in this book, this does not mean that we dismiss the value of such studies. On the contrary, empirical studies are welcome and necessary. It is important to examine how different institutions, including international courts, are organized and function from a constitutional perspective. Such studies should form the basis for any concrete normative proposals.
Dunoff and Trachman would also prefer a bottom-up rather than the top-down approach, which the book is claimed to apply. The intention of the book is certainly not to impose specific constitutional solutions. I agree that such choices should be up to policy-makers. But it is the role of academics to develop the choices available if certain constitutional values are to be respected. This may actually empower the policy-makers in choosing the option that best responds to their objectives.
Finally, a constitutional approach does not mean a farewell to positive law. But it means to accept that international law is not limited to treaties and customary international law. International decisions (binding and non-binding) and judgments are of increasing importance. This growing public character of international law raises not only normative issues, but also questions of the legal significance of such decisions and judgments in positive law.
Daniel Bodansky is right in asking about the added value of a constitutional perspective, especially in relation to global administrative law. I would say that the two approaches have much in common. Global administrative law has set out accountability standards, such as transparency, participation and reasoned decisions. But international constitutional law asks specifically how international institutions could learn from national constitutional law, and how they should inter-act with national constitutional organs. It should also ask how national constitutional organs should respond to the new international setting, as has been argued by Mattias Kumm.
Bodansky also asks whether it might be better to study the different elements of constitutionalism, such as judicial review and democracy, rather than constitutionalism as such. But only a constitutional approach studies the inter-relationship between such elements, for example how to balance legal control represented by judicial review while ensuring ultimate political accountability.
So, a constitutional approach to international law brings a useful perspective. Traditional sources of international law in the form of treaties and customary international law continues to play important roles. But the constitutional approach is of increasing importance as the public character of international law is growing.