Introduction

The United States has entered a new era of national security, one defined by the return of great power competition with China and Russia.1 Across presidential administrations, the federal government has turned away from the heady rhetoric of globalization and the post-9/11 focus on terrorism.2 Today it embraces a broader conception of national security that focuses on vulnerabilities that adversaries might exploit in basic utilities, telecommunication networks, real estate purchases, the food supply, consumer electronics, and social media applications.3 National security concerns now dominate foreign relations,4 and the federal government is deploying a barrage of economic tools, including export controls, sanctions, and investment restrictions, to manage those concerns.5

But the federal government isn’t the only actor on the field. Numerous U.S. states have taken it upon themselves to adopt their own measures, ostensibly to address some of these same concerns. States have prohibited state agencies from doing business with Russian-linked companies, attempted to ban TikTok, barred their law enforcement agencies from using Chinese-made drones, and restricted Chinese nationals’ ability to purchase real estate.6 Some of the states’ actions parallel federal ones, but others go much further.7

The expansion of federal national security actions, coupled with the increasing frequency and breadth of states’ security-focused actions, have set U.S. states and the federal government on a collision course.8 Private parties have already launched a range of legal challenges to state laws, pulling courts into the mix to determine whether, or to what degree, states may act with respect to national security and raising fundamental questions about federal preemption of state laws.9

This Article makes three main contributions to academic and policy debates about federalism and national security. First, we argue that states’ recent national security–related actions do not fit neatly into leading theories about how the federal government interacts with the states, theories that include dual federalism, cooperative federalism, uncooperative federalism, and overcooperative federalism. Dual federalism envisions separate and exclusive spheres for the federal and state governments.10 Foreign relations has been described this way — as the sole province of the federal government — but that has never been totally accurate.11 States have long taken measures that touch on foreign relations and often act to protect their citizens’ security.12 Yet even extant academic theories that accept that federal and state actions overlap do not fully capture states’ recent security-focused actions. Cooperative federalism focuses on instances where the federal government enlists state officials to implement and enforce federal regulatory programs.13 Uncooperative federalism emphasizes instances where states use the regulatory power that the federal government confers on them to challenge or dissent from federal law.14 Overcooperative federalism describes cases where states seek to enforce federal law more aggressively than federal officials do.15 But none of these theories fully encompasses the current situation in which states, acting outside of federal programs, invent a role for themselves by enacting laws that reflect some of the same national security concerns that Congress and the Executive have evinced but that go beyond federal law by imposing broader prohibitions or more stringent requirements or by regulating in an area that the federal government has not.16 We propose a new descriptor — “entrepreneurial federalism” — to better account for such state actions.17

Framing today’s state actions as exemplars of entrepreneurial federalism does not resolve whether such actions are permissible as a doctrinal matter or should be permissible as a normative one. This leads to the Article’s second contribution. Courts considering states’ security-focused actions may be tempted to rely on earlier foreign policy–related preemption cases that broadly disabled states from acting with respect to foreign relations, akin to the dual federalism theory.18 But we argue that there are underappreciated perils in broad preemption. If courts, in their rush to hold state efforts preempted, adopt broad preemption doctrines, deploy capacious language about the federal government’s powers, and take a parsimonious approach to states’ security-related actions, they may inadvertently foreclose two constructive phenomena. The first is states’ useful supplementation of federal efforts to address national security threats, including through gap-filling statutes or enhanced enforcement of the federal scheme.19 The second is the productive friction that states can provide when they operate in this space.20 By this, we mean states’ ability to trigger reason-giving by the Executive that improves the quality of decisions, to challenge groupthink, and to reveal underappreciated costs that federal policies may impose on the states.21

Our view about the potentially productive contributions by states, especially with respect to security-focused actions, leads to the Article’s third contribution: a series of normative recommendations for courts, Congress, the Executive, and states of ways to maximize the benefits of the states’ role while using preemption where necessary to protect the federal government’s management of key national security priorities. Congress and the Executive may choose to preempt state actions as long as they have the constitutional authority to act in a particular space (as they usually do in national security).22 Indeed, there are good reasons for courts to hold that at least some of the state actions regarding China and Russia are preempted or otherwise unlawful.23 However, to preserve states’ ability to provide useful supplementation and productive friction in the future, we urge judges to use the narrowest available preemption theory, so as to avoid displacing more state law than is necessary to protect the federal government’s national security prerogatives. Broad holdings asserting that states have no role in foreign relations or national security would unduly infringe on states’ traditional responsibility to protect their citizens, which is the asserted basis for much recent state activity.24

But Congress and the Executive should do their part too. Congress should legislate with greater clarity when it addresses national security issues of interest to the states by including express preemption provisions that disable states from action or antipreemption provisions that permit state action.25 Congress and the Executive could also file amicus briefs addressing preemption in cases that private litigants have filed challenging states’ actions and thereby provide greater clarity for judges about the extent to which the states are interfering problematically with federal regulatory schemes.26 In addition, executive officials could engage with state leaders, both to educate them about the nature of national security threats and to learn from them about emerging concerns or underappreciated impacts of federal policies on state constituencies.27 State leaders, too, could articulate more clearly the nature of their security concerns, avoid xenophobic motives and rhetoric, tie their actions more tightly to federal standards, and engage Congress to support antipreemption provisions where useful.28

The Article proceeds as follows. Part I details the federal government’s new focus on China and Russia and its increasing reliance on economic tools to achieve its national security goals. It then provides an overview of states’ recent security-focused activities and subsequent litigation. Part II defines the concept of “entrepreneurial federalism” to describe states’ recent actions and contrasts it with existing theories of federalism. Part III highlights the underappreciated perils of broadly disabling states from acting on national security, namely the loss of states’ ability to usefully supplement federal policies or productively add friction to federal decisionmaking. Part IV turns to the normative, addressing how the relevant players can maximize the benefits of the states’ roles while protecting well-considered national security policies by using preemption where necessary.

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* Class of 1948 Professor of Scholarly Research in Law and Vice Dean, University of Virginia School of Law.

* * Professor of Law, Harvard Law School. For helpful comments and conversations, we are grateful to William Alford, Gabriella Blum, Curtis Bradley, Elena Chachko, Amanda Frost, Jean Galbraith, Oona Hathaway, Harold Hongju Koh, Ruth Mason, Martha Minow, Caleb Nelson, Saikrishna Prakash, Richard Re, Matthew Stephenson, and Matthew Waxman; to participants in the 2024 Chicago-Virginia Foreign Relations Law Roundtable, the 2025 Potomac Foreign Relations Roundtable, and the 2025 Federalism Scholarship Roundtable; and to participants in workshops at Berkeley, Boston College, Boston University, Columbia, Georgetown, Harvard, University of Virginia, William & Mary, and Yale law schools. Eichensehr thanks the Harvard Law School Summer Research Program for financial support. The authors are grateful to Alexander Chen, Sareen Ishanyan, Isabelle Melton, and Andrew White for excellent research assistance and to the editors of the Harvard Law Review for trenchant comments and careful editing. This Article reflects developments through mid-October 2025, when it was finalized for publication.