Outcasting: Enforcement in Domestic and International Law

Oona A. Hathaway & Scott J. Shapiro

Is international law law? Though leading scholars have said that it is “futile”1 to try to answer this “tired old question,”2 whether international law is law in fact matters a great deal. Most fundamentally, it matters from the moral point of view. Law’s moral import follows from a basic truth accepted by all but hardcore anarchists: namely, that legal systems are morally valuable institutions. Thus, whether we ought to respect, support, or obey international law depends in part on whether it possesses those properties that make legal regimes worthy of our esteem and allegiance—that is, on whether it is “really” law. But there is an additional—and deeply illuminating—reason why this jurisprudential question ought to be engaged. Responding to the critics who argue that international law is not law allows us to make substantial new progress in answering the very question international law scholars do care about: whether and how international law affects state behavior.

The reason is simple. The principal objection made by critics of international law is that international law cannot be real law because it lacks mechanisms of coercive enforcement. On this objection, since international law lacks mechanisms of physically coercive enforcement, it cannot affect behavior in the right way and hence cannot be a real legal system. It follows that answering the skeptic who doubts that international law is law also answers the skeptic who doubts that international law matters. For in order to respond to the first skeptic, one must show that international law is capable of affecting behavior in the right way to be law. But once one shows that international law matters in the right way, one ipso facto shows that it matters!

No doubt, one could try to answer the question of whether international law matters directly without engaging the central objection to international law as law. But there is a crucial advantage to addressing the former question via the latter. For examining whether international law is law first requires one to figure out all the ways in which legal systems must be capable of affecting behavior to be law. This inquiry opens up a fascinating range of new possibilities about how law might matter to its subjects. With the help of the fuller account that results, it becomes clear that international law is capable of affecting state behavior in the right way to be law; more significantly, it is capable of affecting state behavior in ways that have previously eluded international law scholars. Though international law does not matter to states in the same way that much modern domestic law does, it matters to them nonetheless. International law has mechanisms of law enforcement and these mechanisms give states reason not to violate the law.

In his classic 1832 work The Providence of Jurisprudence Determined, John Austin argued that international law does not meet the basic conditions of law—most notably, there is no sovereign capable of issuing commands.3 H.L.A. Hart famously demonstrated serious flaws in Austin’s argument,4 but it is possible to reframe the essence of Austin’s critique to accommodate Hart’s objections. In this reframed critique, international law is not law because it is (1) not backed by physically coercive sanctions and (2) not administered by members of the system in question. We call these two objections the “Brute Force Objection” and the “Internality Objection.” While the two objections are analytically distinct, they often come together as a package. That package is what we call the “Modern State Conception.”

In our culture, modern state regimes are the paradigm instances of law. The inclination to focus exclusively on the state and to understand all legal phenomena through this lens is thus completely understandable. But it is also, we argue, a grave mistake. Critics of international law have succumbed to this temptation and have taken modern legal systems as their exclusive model for law. They have adopted the Modern State Conception, which maintains that regimes are legal systems only when they possess a monopoly over the use of force within a territory and use this monopoly to enforce their rules. In the domestic context, the monopoly is shared by a host of interlocking bureaucratic organizations that employ intimidation and violence as a method of enforcement, such as police, militia, prosecutorial agencies, and correctional institutions. In the Modern State Conception, then, law matters through the threat and exercise of violence by such organizations. Skepticism about international law naturally follows from this conception given that international law does not possess these bureaucratic institutions or any enforcement apparatus resembling that of the modern state.

The concept of law that lies behind this critique of international law is seriously flawed because of its limited understanding of how rules must be capable of affecting behavior in order to count as law. Its failure stems not simply from the fact that the Modern State Conception insists that legal rules only affect behavior when they are enforced; more importantly, it falters by adopting an excessively narrow conception of law enforcement itself. The Modern State Conception errs by insisting, first, that law can matter only if it is enforced internally, i.e., by the regime itself, and, second, that law can matter only if it is enforced violently, i.e., through the threat and exercise of physical force.

This narrow understanding of law enforcement ignores regimes that outsource enforcement to external parties. Contrary to the Modern State Conception, as long as some party is tasked with using coercion in order to ensure compliance with the rules, the regime itself need not perform the role. We call this externalized enforcement. Moreover, the coercion used to enforce the law need not involve the threat and exercise of violence. Rather, it may involve the threat of exclusion, or as we call it, outcasting. Unlike the distinctive method that modern states use to enforce their law, outcasting is nonviolent: it does not rely on bureaucratic organizations, such as police or militia, that employ physical force to maintain order. Instead, outcasting involves denying the disobedient the benefits of social cooperation and membership.

We argue that different legal regimes can be classified depending on the particular modes of enforcement on which they depend. We illustrate this by dividing law enforcement into internal and external enforcement, and into that which resorts to physical force and that which does not. These two different axes can overlap to create four separate categories: (1) internal and physical; (2) external and physical; (3) internal and nonphysical; and (4) external and nonphysical. To illustrate this, consider the following four-square diagram:

Figure 1: Models of Law Enforcement

Internal External
Physical Modern State Conception External Physical Enforcement


Internal Outcasting External Outcasting

As this diagram makes clear, the Modern State Conception of law enforcement is only one part of the larger picture—it encompasses law that is enforced through internal systems using physical force. But there are three other forms of law enforcement: external physical enforcement (enforced by external actors using physical force), internal outcasting (enforced by internal actors using nonphysical means), and external outcasting (enforced by external actors using nonphysical means).

A dominant mode of enforcement in domestic legal systems for the past two millennia, and one still actively in use in our own federal system today, has involved various forms of external outcasting. The law—in cases as diverse as canon law’s excommunication system and the law of medieval Iceland, which utilized literal outcasting, in lieu of a police force—has routinely used private parties to exile, excommunicate, outlaw, pillory, and shun those who break the rules. The recourse to externalization and outcasting is not simply a response to the technological and economic challenges of assembling a centralized body of individuals who are entrusted with a monopoly on the legitimate use of force. In many legal systems, it is a feature, not a bug: using externalized enforcement and exclusion from the benefits of social cooperation and membership to enforce the law is in keeping with the values of the legal system, while the deployment of brute force is not.

In international law, not only does external outcasting exist, it is also ubiquitous. The concept of external outcasting helps us see a set of common features that run through diverse international legal institutions—features that the Modern State Conception previously rendered invisible. Legal institutions that could not be substantively more different—for example, the World Trade Organization, the Universal Postal Union, and the Montreal Protocol—use the same law enforcement model. That model takes on different forms in different contexts, but in each case external actors enforce the law through exclusion from the benefits of community membership.

Seeing externalized outcasting as a form of law enforcement helps us see that the traditional critique of international law—that it is not enforced and is therefore both ineffective and not real law—is based on a limited and inaccurate understanding of law enforcement. Disobedience need not be met with the law’s iron fist—enforcement may simply involve denying the disobedient the benefits of social cooperation and membership. Once we broaden our understanding of law enforcement to include externalization and outcasting, rather than limiting it to internalization and violence, we see that international law matters in the way that legal systems must matter.

This much more complete picture of law not only gives the lie to the Modern State Conception, but it also provides a new way of understanding international law and its enforcement. Across radically different subject areas—from human rights to trade to the international postal service—international legal institutions use others (usually states) to enforce their rules and typically deploy exclusion rather than physical force. These substantively diverse legal regimes have a set of common features. Once we describe these features—namely, their use of external enforcement and outcasting—we can see that regimes that appear on the surface to be very different are really applications of the same law enforcement model. Meanwhile, variations in the characteristics of outcasting regimes work together to respond to specific challenges.

The more complete picture of international law also sets the stage for a reinvigorated inquiry into some of the central organizing questions in the field of international law today. We show that the phenomenon of externalized outcasting is germane to the efficacy of international law. For if externalized outcasting is a form of law enforcement, then its existence is highly relevant to the task of tallying the successes and failures of international law. Put slightly differently, if the only form of law enforcement one is willing to recognize is intimidation and violence by police, then international law will look pretty ineffective. We contend, however, that there are sources of motivation generated by international law which have hitherto been invisible to scholars and whose existence should be countenanced when deciding whether, when, and how international law matters. Moreover, the deeper and more accurate picture of international law that we provide—one that views externalized outcasting as an important and effective tool of law enforcement—goes beyond providing a more complete picture of international law. It offers a deeper understanding of how international law functions and thus allows scholars and practitioners to more effectively anticipate and address international law’s shortcomings while enhancing its strengths. 


Copyright © 2011 The Yale Law Journal Company, Inc.

Oona A. Hathaway is the Gerard C. and Bernice Latrobe Smith Professor of International Law and Director of the Center for Global Legal Challenges at Yale Law School. Scott J. Shapiro is Professor of Law and Philosophy at Yale Law School. This Legal Workshop article is based on Oona A. Hathaway & Scott J. Shapiro, Outcasting: Enforcement in Domestic and International Law, 121 YALE L.J. 252 (2011), available at http://yalelawjournal.org/the-yale-law-journal/article/outcasting:-enforcement-in-domestic-and-international-law.

This condensed version of Outcasting was prepared by Philip Levitz, Volume 121 Articles Editor.

  1. Andrew T. Guzman, Rethinking International Law as Law, 103 AM. SOC’Y INT’L L. PROC. 155, 155 (2009).
  2. Thomas Franck, Remarks, 103 AM. SOC’Y INT’L L. PROC. 161, 161 (2009).
  4. See H.L.A. HART, THE CONCEPT OF LAW, 44-49 (2d ed. 1994).

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