The United States and other actors such as the European Union impose “targeted sanctions” against foreign officials for acts carried out in their official capacity, or against legal entities of targeted states. This mirrors the practice and experience of the United Nations. The Security Council's practice of imposing comprehensive sanctions in the early 1990s quickly evolved into a practice of “targeted” or “smart” sanctions, to both improve effectiveness and to alleviate the significant effects of sanctions on the population of targeted states. However, the legal regime for resorting to sanctions is different when it comes to states acting unilaterally than it is for collective action within the framework of the UN Charter. This essay first clarifies some terminological issues. It then delves into the legality of the practice of unilateral “targeted sanctions,” and concludes that the most legally difficult aspect of these measures is their purported extraterritoriality.

Enforcement by way of unilateral economic sanctions has been described as “one of the least developed areas of international law.” The term “sanctions” is notoriously difficult to define and does not itself appear in the key international instruments. With economic sanctions regularly referred to as President Trump's “weapon of choice,” and with opposition to such measures growing, greater certainty is needed in this area of law if the legitimacy and effectiveness of sanctions are to be preserved. This essay distinguishes UN-authorized sanctions from three types of “autonomous” sanctions (collective corrective sanctions, unilateral corrective sanctions, and unilateral coercive sanctions) and argues that many uses of unilateral sanctions are either unregulated or based on questionable legality.

Financial and economic sanctions are often adopted to serve multiple ends, including deterrence and prevention, but they are best understood as a tool to incentivize change in a target's behavior. In pursuit of this coercive objective, it is generally—but not always—the case that sanctions are more effective when they are imposed multilaterally, and the broader the coalition the better. This is because multilateral sanctions leverage the diverse sources of pressure that coalition partners can bring to bear on a target and carry with them the legitimacy of broad international support. Taken to its extreme, this argument may suggest that sanctions should always be multilateral, whether adopted through the United Nations, another forum, or an ad hoc coalition. But as we explain below, there are at least two significant reasons that militate in favor of unilateral sanctions. First, within the broad limits of international law, every country must retain the authority to impose sanctions to protect its sovereign security interests, even when it cannot muster a coalition of like-minded allies or a sufficient number of votes—and avoid a veto—on the UN Security Council. Second, imposing “smart” sanctions is actually a difficult business, requiring a complex administrative apparatus to design, build, implement, enforce, and defend them. International institutions, including the United Nations, are inherently less able to build the necessary structures to effectively enforce sanctions. For all of these reasons, two systems of sanctions—one national, one supranational—will likely coexist into the future.

With the Trump administration's reimposition of financial sanctions on Iran, the power of the weaponized dollar is yet again making headlines—and putting distance between the United States and its allies. The dollar's special status as the world's key currency affords the United States an unrivaled sanctioning power. Because access to dollars is a near-necessity for multinational businesses and financial institutions, the United States can unilaterally impose costly sanctions by denying such access to a target—whether a state, company, or individual. This capability is one form of the “exorbitant privilege” afforded to the United States by the dollar's international role. This essay considers why the dollar's status affords the United States this sanctioning power and how the United States exercises it. I first summarize the nature of the dollar's role. Next, I explain the means by which the United States has weaponized that role, especially through financial sanctions. I conclude by offering some potential limitations on that power and exploring the ways in which other countries might seek to erode it.

The United States has employed targeted sanctions—economic and travel restrictions imposed directly on natural and legal persons—in a wide range of policy areas in the past two decades. This includes counterterrorism, nonproliferation, and cyber, as well as sanctions regimes aimed at changing the behavior of various governments. A substantial literature has considered the compatibility with international human rights law of the targeted sanctions practices of other actors, particularly the UN Security Council and the European Union. But relatively few scholars have examined U.S. targeted sanctions practices from that perspective. This essay argues that in principle, current U.S. designation practices can be reconciled with international standards. However, a more robust conclusion about the practices’ compatibility with international human rights law would require more information on the application of designation procedures in individual cases.

In the international legal order, sanctions are valued for their coercive and stigmatizing functions. Through the imposition of financial or other costs, these measures seek to induce compliance with international law by those who are targeted. They also aim to signal the sender's commitment to the violated norm and stigmatize an actor responsible for wrongful behavior. In light of these functions, this essay examines the factors to assess when evaluating the efficacy of unilateral targeted sanctions in enforcing international law. The issue is relevant not only for political scientists, but also for international lawyers interested in ensuring compliance with international norms.