International law has traditionally been just that—international. Consisting of a largely separate set of legal rules and institutions, international law has long governed relationships among states. Under the traditional rules of international law, the claims of individuals could reach the international plane only when a state exercised diplomatic protection and espoused the claims of its nationals in an international forum. More recently, international law has penetrated the once exclusive zone of domestic affairs to regulate the relationships between governments and their own citizens, particularly through the growing bodies of human rights law and international criminal law. But even in these examples, international law has recognized a clear demarcation between domestic and international politics.
The classic model of international law as separate from the domestic realm reflects the traditional problems the international legal system sought to address, namely the facilitation of state-to-state cooperation and the treatment of one state’s nationals by another state. Whether regulating the immunities of diplomats or the rights of ships on the high seas, the traditional purposes of international law have been interstate, not intrastate.
This foundation of international law reflects the principles of Westphalian sovereignty, often seemingly made up of equal parts myth and rhetoric. In this conception, the state is a defined physical territory “within which domestic political authorities are the sole arbiters of legitimate behavior.” States can be part of the international legal system to the degree they choose by consenting to particular rules. Likewise, they can choose to remain apart, asserting their own sovereignty and eschewing international involvement. Formally, Westphalian sovereignty is the right to be left alone, to exclude, to be free from any external meddling or interference. But it is also the right to be recognized as an autonomous agent in the international system, capable of interacting with other states and entering into international agreements. With these background understandings of sovereignty, an international legal system, consisting of states and limited by the principle of state consent, emerged.
Today, however, the challenges facing states and the international community alike demand very different responses from and thus new roles for the international legal system. The processes of globalization and the emergence of new transnational threats have fundamentally changed the nature of governance and the necessary purposes of international law in the past few years. From cross-border pollution to terrorist training camps, from refugee flows to weapons proliferation, international problems have domestic roots that an interstate legal system is often powerless to address. To offer an effective response to these new challenges, the international legal system must be able to influence the domestic policies of states and harness national institutions in pursuit of global objectives.
To create desirable conditions in the international system, from peace, to health to prosperity, international law must address the capacity and the will of domestic governments to respond to these issues at their sources. In turn, the primary terrain of international law must shift—and is already shifting in many instances—from independent regulation above the national state to direct engagement with domestic institutions. The three principal forms of such engagement are strengthening domestic institutions, backstopping them, and compelling them to act.
The most striking feature of this conception of international law is a direct emphasis on shaping or influencing political outcomes within sovereign states in accordance with international legal rules. Even in 1945, the drafters of the U.N. Charter still maintained the classical position that international law and institutions shall not “intervene in matters which are essentially within the domestic jurisdiction of any state.” Today, however, the objectives of international law and the very stability of the international system itself depend critically on domestic choices previously left to the determination of national political processes—whether to enforce particular rules, establish institutions, or even engage in effective governance. By ensuring that national governments actually function in pursuit of collective aims, international law is starting to play a far more active role in shaping these national political choices. Assuming that current political, economic, and technological trends continue, the future effectiveness of international law will turn on its ability to influence and alter domestic politics.
These functions of international law are already well known to the members of the European Union (“EU”). Indeed, in extending membership to ten new countries over the course of the past decade, the EU has relied on EU law as its primary tool of reform and socialization. Even among the original member states, EU institutions continue to perform the types of backstopping, strengthening, and mandating functions described here. Europeans themselves are coming to recognize these uses of law; a new generation of European policy thinkers has openly proclaimed the virtues of the European way of law.
Some may, of course, argue that these new functions of international law have no applicability outside the European context in which they were first embraced. Yet each of the three means through which international law is coming to influence domestic outcomes—strengthening domestic institutions, backstopping national governance, and compelling domestic action—is spreading beyond the Continent.
To the extent that what we describe as the “European way of law” is already evident both within the EU and now in a growing number of other contexts, this Article describes an important reorganization of the means and mechanisms through which international law operates. Our argument goes further, however, by suggesting that these new mechanisms of international law have the power to make the system as a whole far more effective. We therefore move beyond description and prediction to prescription, suggesting ways that the European way of law should become the future of international law writ large.
We also recognize, however, the potential dangers in current trends. As we emphasize in the conclusion, our vision of the principal future functions of international law assumes an intensive interaction between international law and domestic politics. But domestic politicians can manipulate international legal institutions and mandates to serve their own purposes, such as jailing political dissidents as part of complying with a Security Council resolution requiring domestic action against terrorism. More broadly, the basic positivist foundations of international law, requiring states to freely accept such interference in domestic politics, raise the possibility of manipulation and even imposition of such “acceptance” as a result of power disparities.
Part I of this Article identifies a new set of global threats and actual and potential responses, including the EU’s uses of law to transform new members “from the inside out.” Part II argues that the future relevance, power, and potential of international law lie in its ability to backstop, strengthen, and compel domestic law and institutions. Part III examines the potential pitfalls and dangers of these new functions of international law. Finally, Part IV contrasts our analysis with other recent efforts to blur the boundaries between the international and domestic spheres, noting that what is distinctive about our claim is not the intermingling of two kinds of law, but rather the impact of international law on domestic politics and vice versa…