Rethinking the Legal Foundations of the European Constitutional Order: The Lessons of the New Historical Research

I. INTRODUCTIONWhat drives the choice of European law as a field of study and scholarship? For many, the answer rests in the puzzle of the emergence of a powerful rule of law in a political system that, for all intents and purposes, began in the anarchical international sphere.1 Through the constitutionalization of the founding treaties, the politics of state power and national interest have been replaced by the rule- bound behavior and the equality, predictability, and stability of a conventional legal system. In other words, in the eyes of many, the European legal system has left behind the shortcomings of public international law-most importantly the suspicion that international law is not really law at all because the rules are the product of state power and mutual interest and, once they no longer serve such ends, can be broken with impunity-and has adopted the civilizing principles of law in what approximates a federal legal order.2 As this characterization suggests, at least part of the attraction of European law rests in the fact that constitutionalization presents an empirical puzzle with a strong moral dimension.While constitutionalization has been at the heart of scholarship in law and political science for decades, it has only recently captured the attention of legal historians. With their distinct methods and sources, they have already contributed in fundamental ways to our understanding of the constitutional paradigm, and given the highly ambitious research programs of Morten Rasmussen, Bill Davies, and others, they will undoubtedly continue to do so. In this essay, I review some of their claims and findings from the perspective of the legal discipline. In Part II, I argue that historical research has uncovered a legal dimension of the constitutionalization process that has been missing from the dominant account and that implicitly draws on and sheds light upon concepts and theories that are central to the field of comparative law. In contrast with the conventional account in both the law and political science, which contains a fairly thin rendition of the legal process centered on a supranational court (the Court of Justice) interpreting a single supranational text (the Treaty of Rome), legal historians have documented the variety of legal actors and the multiplicity of domestic legal sources that combined, through a process of legal transplants, to fashion the supranational constitutional apparatus.3 Pluralism and cross-national variation in the types of professionals and institutions responsible for crafting the law, as well as the migration of legal concepts between jurisdictions, are central themes in the field of comparative law, and historical research has revealed the importance of understanding such variation and transplantation in the relatively understudied domain of public and supranational law.In Part III, I argue that the lessons that are sometimes drawn by legal historians for contemporary normative and philosophical debates on the nature of the European constitutional order are less persuasive. It is sometimes argued that, since the process that led to the rise of what is alternatively called the "constitutional narrative" or "constitutional practice" was more contested and contingent than is normally believed to be the case, the existence, today, of a quasi- federal constitutional order is questionable. To simplify somewhat, the claim is that constitutionalization is a story told by a small cadre of starry-eyed and ideologically motivated lawyers and that it does not reflect the current realities of the member states, which continue to privilege national over European law and to give effect to European law only sporadically.4 Although there is some support for this view, I argue that there is significant countervailing evidence and that the constitutional paradigm therefore remains a useful framework for conceptualizing European law.II. EUROPEAN LEGAL HISTORY AND COMPARATIVE LAWIn the conventional account of how the doctrinal apparatus and the routine practice of the European constitutional order came to be established, the legal dimension, namely the institutions, actors, sources, and methods that combined to produce the law, is quite thin. …