ver the past decade, cities have quickly assumed a place on the global stage. From the Chicago Climate Charter, signed by mayors of more than 50 cities, to immigration debates raging around the world, cities are meaningfully influencing global political discourse. Yet, international law—the primary system of norms, rules, and institutions through which the international order has been constructed—has remained off limits to cities and other non-state actors. The result is a disconnect between cities’ growing role in global affairs and their continued exclusion from the formal structures of the international system.

The disconnect between cities and international law should not be surprising. The international legal system has always been a system of nation states. Emerich de Vattel’s famous treatise from 1758 is titled Le Droit de Gens (The Law of Nations) and its subtitle makes clear that the system is based on the “principles of the law of nature applied to the conduct and affairs of nations and sovereigns.” The ticket for admission to the international legal system was then, and remains today, sovereignty—the full right to govern without outside interference. Nation states alone enjoy such sovereignty. Cities, as subordinate actors within a state, do not. Hence cities have been excluded from the formal institutions of the international order.

While the formal rules of participation in international law have led international organizations, national governments, and the international lawyers in their employ to overlook cities, cities have quietly become important actors in international legal processes. Cities contribute to international norm development and enact policies that promote (or impede) rule compliance. Cities’ commitments in the Chicago Climate Charter, for example, may well do more to shape climate norms than the proclamations of some heads of state. City implementation of low carbon transportation options or favorable building codes may make a greater contribution to meeting the 2°C goal than some state-level policy choices. The incorporation of an international human rights agreement into municipal legislation or cities’ voluntary self-reporting of SDG compliance to the UN may have a more direct impact on rights enjoyed by that city’s residents than would an equivalent national commitment.  Cities’ commitments to the November 2019 Paris Call for Trust and Security in Cyberspace are an essential component of a broad coalition of actors needed to fill a troubling governance gap. Today, the success or failure of international agreements may well turn on cities’ engagement in and compliance with them. Yet, the lawyers who make and implement the rules of the international system, usually on behalf of states, largely continue to ignore city actions, overlooking a critical component of the global governance architecture that could help advance international rule development and compliance.

Despite cities’ growing impact in global politics, mayors and municipal authorities have yet to find their voice in the international legal system. Cities are only just beginning to develop capacities and expertise in international law or international institutional engagement. When cities do participate in international negotiations, they are usually relegated to the outer-most ring of concentric circles of meetings and dialogues as representatives of civil society, not formal participants. Even at a conference about cities—Habitat III, for example—cities themselves were part of an external engagement process by states, rather than negotiators themselves.

Moreover, the connective fabrics that could link the traditional, formal architecture of international law to cities and other sub-state actors is significantly underdeveloped. Groups of cities frequently make proclamations from outside the formal negotiations, such as that of the 5th Mayoral Forum on Human Mobility, Migration and Development on the sidelines of the Intergovernmental Conference on the Global Compact for Save Orderly and Regular Migration, hoping they will be heard by the actual state negotiators “in the room where it happened.” Nowhere was this better illustrated than at the 2018 Buenos Aires U20, immediately preceding the G20 summit. Despite the support of the host Government of Argentina and the City of Buenos Aires, the Communique of the U20, theoretically a “roadmap to the G20 leaders” did little to inform formal international policymaking in the G20 Leaders’ Declaration. If cities want to actually influence international rule development and harness the power of international law to advance their own municipal interests on issues of global affairs, they need to operate in the domain of international law with the help of international lawyers.

Four shifts are required to bridge this gap between city policies and international law.

First, mindsets must change. Cities need to recognize that they will be more effective contributors to global governance if they speak the language of international law and that by harnessing international law they can advance their own local agendas. On the other side of the divide, international lawyers must recognize that cities can and do make a difference in rule creation and compliance.

Second, new capabilities are needed. Cities need to build expertise and experience in international law, whether in their solicitor generals’ offices or in international affairs departments. New York, Los Angeles, and London have taken important strides in this respect and other cities would benefit from following their lead. International lawyers need to understand cities’ authorities, jurisdictional reach, and potential governance contributions.

Third, cities and international institutions need to work together to build better connective fabrics linking city policy activities and international rule-making and compliance efforts. Such connective fabrics could include new formal and informal relationships, creative new forms of membership and participation, and direct inclusion of city actions/commitments in formal international agreements. The decision by the UN to accept a voluntary local review of SDG compliance from New York City is a potentially promising new model to directly connect local governance and international institutional processes.

Fourth, and perhaps most radically, the formal rules of international law may need to adapt overtime to the growing role of cities in global politics. Traditional international legal formalism that limits participation to sovereign states may need to accommodate other actors, such as cities, in a more meaningful way. One approach would be to give cities a limited, but formal voice—what lawyers might call conditional international legal personality—to the degree that and within the substantive domains in which cities can make meaningful functional contributions to solving global policy challenges. For example, in an international climate negotiation considering the impact of urban transport policies cities would have a legal voice commensurate with their ability to advance the climate governance agenda. Similarly, in a human rights treaty compliance discussion on police brutality, cities would have a loud voice. In contrast, in a nuclear arms or international trade negotiation, cities legal personality would be far more circumscribed, remaining subordinate to a national government.

As cities and international lawyers start to talk to one another, both will benefit, as will the collective effort to address global policy challenges. Cities can influence global norms by engaging with the international legal system directly, particularly where their policy preferences diverge from those of their national authorities. So too, cities can harness the existing power of international law as political and legal leverage to advance their own local agendas. International lawyers and international institutions will find urgently needed political will—too often lacking among national governments today—in the world’s cities. At a moment when the distribution of power and preferences among nation states is changing so rapidly, incorporating cities into the international legal system may well result in new, and perhaps unforeseen, geopolitical realignments among cities, states, and international institutions. It may even yield a new political force to shape international norms and, perhaps, a broader reimagination of the nature of international and transnational politics.

This channel is a collaboration between the Diplomatic Courier and the Great Powers and Urbanization Project. This essay was adapted from the Workshop on Cities, Geopolitics, and the International Legal Order held at the University of Pennsylvania’s Perry World House in September, 2019. It was made possible, in part, by a grant from Carnegie Corporation of New York.
William Burke-White
William Burke-White is Visiting Scholar at The Brookings Institution and Professor of Law at the University of Pennsylvania Law School.
The views presented in this article are the author’s own and do not necessarily represent the views of any other organization.