To intervene or not to intervene? This question has dominated global politics over the past five years, in regions as diverse as the former Yugoslavia, Afghanistan, Iraq, and the Sudan. Yet the question is as old as international relations and is a logical extension of the institution of sovereignty. Indeed, it was with the rise of sovereign states that the notion of an exclusive jurisdiction, free from the meddling of outsiders, came to have normative value. Since that time, as Karen Feste notes, patterns of intervention have shaped the international system, “defining contours of connection between its units, guiding interaction, and creating operational expectations” (p. xiii).

Feste defines intervention as “a foreign policy tool of strong states seeking to force their will on weaker ones through temporary, limited acts of defined scope” (p. xiv). But as recent events in Kosovo, East Timor, and Iraq have demonstrated, interventions in this new century have defied the expectations of scholars and practitioners with respect to their duration. In contemporary international relations, the reconstruction of a society's security, legal, and economic infrastructure is viewed as essential if the purposes of the original intervention are to be realized. Some, such as Robert Keohane, even suggest that “[d]ecisions ‘before intervention’ should depend, to some extent, on prospects for institution-building ‘after intervention’” (p. 276).

These two books assume different theoretical and normative postures with respect to the intervention dilemma. For Feste's Intervention, the focus is the United States—more specifically, the philosophy that underpins U.S. intervention in the twenty-first century. By describing how the United States has structured its responsibilities through intervention in the past, Feste endeavors to formulate a more coherent doctrine for American policymakers in the present. The main drawback of such an approach (as she herself admits on p. 234) is that the search for a U.S. “intervention doctrine” is ultimately illusive. While the so-called Vietnam Syndrome continues to affect U.S. policymakers, particularly in their choice of military strategy, this hardly constitutes the coherence and consistency that one would expect from a doctrine. The only mantra she uncovers that resembles a guiding philosophy for U.S. intervention is the idea of “selective engagement”—an umbrella concept that can justify just about anything (including inaction). The author also faces obstacles when she attempts to quantify the variables associated with an intervention decision. For example, in Chapter 5, she rates the degree of U.S. national interest at stake in different crises of the last two decades. In the case of Somalia (1992), we are told that the national interest meter read “medium,” whereas in Rwanda two years later, it read only “low.” But how scientific is this reading, and what is the time horizon for the measurement? At the time, in 1992, it was not at all clear that the United States had pressing national interests in Somalia, yet George H. W. Bush was persuaded that action to halt a pending humanitarian crisis was the “right thing to do.” In 1994, still smarting from the very public display of U.S. soldiers being dragged through the streets of Mogadishu, the U.S. government made a different calculation about the imperative to act in Rwanda. It is questionable whether a measurement of national interest can offer a robust explanation of these contrasting responses.

These methodological challenges hint at an additional problem with Feste's work: the lack of a guiding theoretical framework. Her efforts to discuss intervention through the lenses of two main bodies of international relations theory—neorealism and constructivism—yield very little. From the perspective of neorealism, we learn that the United States contributes to the evolving structure of the international system through its intervention policies. But this insight is short on specifics, particularly with respect to what explains U.S. behavior. As Feste argues, global structure only “helps shape a superpower's response to world problems once its form is clear, widely accepted, and firmly set” (p. 1). And even then, she rightly points out, unipolarity does not guarantee hegemony.

By contrast, J. L. Holzgrefe and Keohane largely avoid the paradigms that dominate the discipline of international relations in prominent journals of political science, and draw upon well-known scholars from philosophy, ethics, and law. Thus, while they narrow the subject matter by focusing on a particular kind of intervention (interventions to prevent or end widespread suffering and/or grave violations of human rights), they offer a wider range of perspectives. Moreover, their driving questions are prescriptive rather than descriptive. Drawing from the words of UN Secretary General Kofi Annan: “On the one hand, is it legitimate for a regional organization to use force without a UN mandate? On the other, is it permissible to let gross and systematic violations of human rights, with grave humanitarian consequences, continue unchecked?” The starting point for all of the contributors to this edited collection is that humanitarian intervention, in some cases, can be justified. In short, sovereignty is not and should not be absolute. But the authors differ with respect to the legality of humanitarian intervention and its desirability as a practice in contemporary international society.

The focal point for analysis throughout Humanitarian Intervention is the process of change in international relations—most notably whether and how shifts in norms relating to human rights are changing the institution of sovereignty. For liberal international lawyer Fernando Teson, humanitarian intervention has become both a right and a duty for members of international society when the human rights of individuals, wherever they reside, are being abused. In Teson's view, the principle of nonintervention enshrined in the United Nations Charter and other instruments of international law is a “doctrine of the past” that “feeds on illiberal intellectual traditions,” such as relativism, communitarianism, and nationalism (p. 128). If liberals are correct in describing the major purpose of states and governments as the protection and promotion of individual human rights, then the logical corollary, he argues, is that state sovereignty has only instrumental—not intrinsic—value. The ultimate objective, then, is to bring international law in line with an international morality that is giving increasing weight to the condition of individuals (as opposed to sovereign states).

Legal scholars Simon Chesterman and Michael Byers challenge Teson's willingness to override the principle of nonintervention by emphasizing its egalitarian underpinnings and its crucial role protecting weaker states in the international system. Drawing upon key developments in the customary law regulating the use of force, Chesterman and Byers insist that interventions, such as those in Northern Iraq (1991) and Kosovo (1999), can only be justified through a plea to “exceptional legality.” For them, Teson's desire to change the content of that law is indicative of an even deeper problem: a movement on the part of a small group of “Anglo-American” lawyers to impose a new legal regime against the opinion of legal scholars in the developing world. This exercise in legal hegemony, they argue, “detracts from, and may undermine, the significant advances over the past half century in the fields of human rights and conflict prevention” (p. 179).

The contribution of philosopher Allen Buchanan occupies an intriguing position between these two opposing positions. On the one hand, Buchanan appears sympathetic to Teson's liberal impulse: Humanitarian intervention can be viewed as legitimate if it meets a “Simple Moral Necessity Justification” (p. 132). Yet the author imposes a further hurdle by arguing that states seeking to change international law, and promote human rights through intervention, must meet a set of legal criteria as well. In other words, there are both justifiable and unjustifiable attempts to reform international law. Buchanan's key example is the Kosovo intervention, where, in his view, NATO countries failed to provide a compelling alternative rule to the existing requirements of Security Council endorsement for military intervention. As a result, he concludes, the intervention was an unjustified effort in legal reform.

As my analysis suggests, the ghost of the Kosovo war hovers above most of the chapters in this volume. While the influence of that controversial intervention leads to stimulating and highly original contributions, one wonders how the authors would respond to the two wars that have followed the terrorist attacks of September 11. In the initial aftermath of 9/11, it appeared as though the divisive issue of humanitarian intervention would fall off the policy agenda as Western states struggled to develop a new strategy to fight terrorism. Nonetheless, as the last two chapters by Keohane and Michael Ignatieff suggest, there are two important ways in which humanitarian intervention connects with the broader war on terrorism.

First, it is clear that post–Cold War changes in the conception of sovereignty and the troubling phenomenon of so-called failed states, both of which fueled the interventions for humanitarian purposes in the 1990s, remain as relevant as ever in a post–9/11 world. The terrorist acts of 2001 brought home to Western states the reality that instability within or collapse of a state anywhere in the world can have implications that reach far wider than that particular region. Second, the debate over humanitarian intervention has revived the just-war discussion about the constraints that should be placed on the use of force in international society. These just-war principles—which include just cause, last resort, and proper authority—animated many of the discussion about the use of force in Afghanistan and Iraq. It was the last of these, authorization, that for many states provided the ultimate test of whether to join the American-led coalition to topple Saddam Hussein.

Yet even before 9/11, it was questionable whether authorization itself was really the key issue in the debates about whether or not to intervene for humanitarian purposes. As Chesterman and Byers remind us, clarity on who can authorize intervention will not make action inevitable: “States are not champing at the bit to intervene in support of human rights around the globe, prevented only by an intransigent Security Council and the absence of clear criteria to intervene without its authority. The problem, instead, is the absence of the will to act at all” (p. 202). As the events of the summer of 2004 in Darfur painfully show, it is that intangible quality, political will, that continues to make all the difference.