The Constitutionality of State and Local 'Norm Sustaining' Actions on Global Climate Change: The Foreign Affairs Federalism Grey Zone

85 Pages Posted: 28 Oct 2019 Last revised: 9 Dec 2020

Date Written: June 1, 2020


States and cities have long been leaders on global climate change by participating in international meetings, forming cross-border alliances, entering into bilateral memoranda of understanding, and even harmonizing their regulatory systems, as in the case of the California-Quebec emissions trading program. Such subnational efforts have taken on a new importance in the wake of President Trump’s withdrawal of the United States from the Paris Agreement on climate change. Although states and cities cannot be parties to this international agreement, they can contribute to its success by engaging in what I describe as “norm sustaining” activities. However, how can such norm sustaining activities survive constitutional scrutiny when the Supreme Court has often said the nation should speak with “one voice” on foreign affairs?

The analysis of several different cross-border climate agreements between subnational actors raises some concern, especially for California’s linked cap-and-trade program with Quebec, which the Trump administration has challenged in court. Under the Compact Clause, the presumed constitutionality of existing agreements between states and foreign governments largely turns on the assumption that the interstate doctrine applies. Under the Supremacy Clause, the Supreme Court’s expansive reading of executive power could be interpreted to give preemptive effect to President Trump’s repudiation of the Paris Agreement. If California’s emissions trading program is perceived as a tax under the dormant Foreign Commerce Clause, then the requirement that the nation speak with one voice on international commerce could be violated.

However, two trends—one legal and one factual—suggest otherwise. First, the legal and historical justifications for foreign affairs exceptionalism may make less sense in today’s society than at our nation’s founding. Recent cases suggest that the Supreme Court may be more likely to treat foreign affairs like domestic matters, at least where national security is not at issue. Second, when one considers the other ways in which state and local governments have engaged in the grey zone of foreign affairs law—such as by conducting trade and investment missions, entering into agreements to facilitate cross-border legal processes, and engaging in human rights treaty processes —subnational climate actions do not seem so extraordinary. Even the agreement creating the California-Quebec emissions trading program is similar to other cross-border activities, such as an agreement between New York and Quebec on driver’s licenses and an agreement between states and provinces on the Great Lakes. Through a unique analysis that situates subnational climate change agreements within a broader legal and factual context, this Article argues that cross-border climate action by states and cities is well-positioned to survive constitutional scrutiny.

Keywords: Climate change, constitutionality, California, cap-and-trade, Quebec, state and local government, Paris agreement, Compact Clause, Treaty Clause, Supremacy Clause, Foreign Commerce Clause, dormant foreign affairs

Suggested Citation

Murthy, Sharmila, The Constitutionality of State and Local 'Norm Sustaining' Actions on Global Climate Change: The Foreign Affairs Federalism Grey Zone (June 1, 2020). 5 U. PENN. J. L. & PUB. AFF. 35, Suffolk University Law School Research Paper No. 19-23, Available at SSRN: or

Sharmila Murthy (Contact Author)

Suffolk University Law School ( email )

120 Tremont Street
Boston, MA 02108-4977
United States

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