From jus ad bellum to jus ad vim: recalibrating our understanding of the moral use of force.

Author:Brunstetter, Daniel

In the preface of the 2006 edition of Just and Unjust Wars, Michael Walzer makes an important distinction between, on the one hand, "measures short of war," such as imposing no-fly zones, pinpoint air/missile strikes, and CIA operations, and on the other, "actual warfare," typified by a ground invasion or a large-scale bombing campaign. Even if the former are, technically speaking, acts of war according to international law, he proffers that "it is common sense to recognize that they are very different from war." While they all involve "the use of force," Walzer distinguishes between the level of force used: the former, being more limited in scope, lack the "unpredictable and often catastrophic consequences" of a "frill-scale attack." (1) Walzer calls the ethical framework governing these measures jus ad vim (the just use of force), and he applies it to statesponsored uses of force against both state and nonstate actors outside a state's territory that fall short of the quantum and duration associated with traditional warfare. Compared to acts of war, jus ad vim actions present diminished risk to one's own troops, have a destructive outcome that is more predictable and smaller in scale, severely curtail the risk of civilian casualties, and entail a lower economic and military burden. These factors make jus ad vim actions nominally easier for statesmen to justify compared to conventional warfare, though this does not necessarily mean these actions are morally legitimate or that they do not have potentially nefarious consequences.

Just war scholars, however, often do not differentiate between force and war, but rather talk about bellum justum as if all uses of force implied the same moral challenges. The tendency is therefore to evaluate forces short of war through the lens of jus ad bellum. (2) We question whether this assumption is warranted. In particular, we inquire whether jus ad bellum offers a useful moral framework for assessing the acts of force short of war that increasingly characterize global conflict. Thus, in the first part of the article, we articulate the limitations of jus ad bellum principles in evaluating recent trends in international affairs--such as the rise of nonstate actors and the advancements in precision weapons technology (for example, drones)--that have weakened the sovereignty norm and facilitated small-scale uses of force to combat perceived threats. We argue that the jus ad bellum framework does not offer sufficient leverage for assessing the jus ad vim actions that have become the hallmarks of the Obama administration's approach to combating terrorism.

While some scholars have begun to imagine how jus ad bellum principles might look different when adapted to the use of limited force against nonstate actors, there has been no systematic attempt to theorize about jus ad vim. (3) We therefore ask: What would a theory of jus ad vim that counters the shortcomings of the jus ad bellum framework look like? In the second part of the article we contend that a viable theory of jus ad vim can be constructed by recalibrating jus ad bellum criteria and adding a new principle--the probability of escalation. Determining the moral distinctiveness of jus ad vim helps us evaluate the spectrum of options available to statesmen, which range from nonviolence, to force short of war, and ultimately to war itself. However, we warn that jus ad vim raises a host of tensions that just war theorists must be mindful of, and point to some challenges to which thinking in terms of jus ad vim may itself give rise. We also raise questions about jus ad vim that open up future paths of research on the topic.


  1. A. J. Coady identifies a recent trend in forms of violence, namely, that "the last quarter of the twentieth century and the beginning of the twenty-first century have seen a dramatic decline in warfare understood as direct state-to-state conflict." (4) An important part of this shift is due to the rise of nonstate actors, such as al-Qaeda and its affiliates, which pose significant threats to international peace and security, but do not have international legal status and operate in the porous or disputed border regions of sovereign states. As states seek to respond to the perceived threat of terrorism, the struggle against nonstate actors has led to the diminished importance of geographic boundaries in circumscribing the legitimate use of force, and raised questions about the violability of a state's right to territorial integrity. This process began in the 1990s, a decade that saw humanitarian crises in Rwanda and the Balkans challenge the viability of the legalist paradigm. The ensuing debates about the sanctity of territorial integrity, followed by the emergence of the Responsibility to Protect norm, mark a key shift in traditionally state-centric just war thinking, which considered the violation of territorial sovereignty an exception to the sovereignty norm.

With regard to nonstate actors, Eric Heinze argues that their rise has led to the emergence of a "regime of non-state responsibility," which means that weak states are not responsible for what goes on within their (uncontrolled) borders. But the consequences, Heinze argues, are two-fold. First, it has led to "the expansion of the right of self-defense under international law," in a "limited and targeted fashion," against nonstate actors within another state (Heinze cites a 2002 drone strike against al-Qaeda as a legal precedent). Second, this new regime has caused the loosening of "the normative and legal constraints on using force against states for their tolerance of such activity within their borders." (5) The result is a serious challenge to the territorial definition of sovereignty. While Heinze suggests this may increase the likelihood of interstate conflict, the limited scope of such actions--particularly in the case of drones--has not yet led to expanded conflict, but rather has increased instances of jus ad vim.

While war used to be easily defined as a zone of combat where lethal force was justified (to be distinguished from a zone of peace, where it was not), the struggle against terrorism has created "in-between spaces" of moral uncertainty where force is used on a consistent and limited scale, but war is not declared. (6) These are places where terrorist groups have taken up residence and the host country does not have the will and/or capacity to deal with the threat they pose, such as in the border areas between Pakistan and Afghanistan or the southern region of Yemen. Who has the right to address the threat emanating from these places, and with what level of force? Walzer's conclusion--that international policing actions, in conjunction with actions by local authorities, should be tried first--is intuitively appealing. If these fail, then the unilateral use of lethal force by the state that feels threatened would become warranted. However, the ethical challenge lies in determining when the threshold separating international policing and unilateral force has been crossed, and what level of force is justified.

The response by the United States to the events of 9/11 serves as an illuminating example. The Authorization for the Use of Military Force passed by Congress in September 2001, in conjunction with President George W. Bush's classified Memorandum of Notification, signed in September of that year, gave the CIA the right to kill members of al-Qaeda in anticipatory self-defense virtually anywhere in the world. Bush's struggle against al-Qaeda, however, took place predominantly within the framework of traditional just war thinking by waging war against sovereign states wherein al-Qaeda was perceived (not always accurately) to be operating--most notably, Afghanistan and Iraq. And insofar as he undertook only a few jus ad vim acts, the ethical concerns they raised, while duly noted by a few scholars, remained peripheral to broader just war debates. Nevertheless, his policies opened the way for a mode of conflict that transcends international borders.

President Barack Obama, despite rejecting Bush's view of jus ad bellum, has continued--indeed expanded--the precedent established by his predecessor. What paved the way for this shift was, first, the perceived failure of the Bush doctrine. Citing as consequences of the Bush approach an "overstretched" budget, a "resurgent" al-Qaeda, a "strengthened" Iran, and the tarnished global image of the United States, Obama dearly repudiated the jus ad bellum "mind-set" that legitimated the Iraq war. (7) A second element that facilitated this shift was Obama's use of drone technology. From a political perspective, drones provide a precise and calibrated tactic for addressing the security threat linked to nonstate actors. They can be used to target combatants, while significantly reducing the risk to U.S. troops and diminishing the number of civilian casualties, (8) The result has been a six-fold increase in drone strikes in Pakistan under President Obama and an increase of strikes in several other countries, such as Yemen and Somalia. (9) This use of violence, while certainly less intense and widespread than that of the multiple wars waged by the Bush administration, nevertheless raises serious human rights concerns.

Forces Short of War and the Issue of Human Rights

The concept of just war must weigh two views of rights against each other: a state's right to sovereignty and universal human fights (especially those of noncombatants). In an ideal world, a just use of force should satisfy both, but the reality is that there are no easy answers as to the right balance. Some scholars suggest that just war thinking reinforces individual human rights because it requires the protection of noncombatants and endorses the Responsibility to Protect doctrine, while critics argue that just war principles condoning the violation of state...

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