As of 2010, aggression became a crime for which individuals can be tried at the International Criminal Court. While this development may appear minor to some, it represents a significant turn both in jus ad bellum and in the ambit of the court. It appears especially relevant today, as the world still grapples with how to respond to Russia's annexation of Crimea, Turkey's attacks on northern Syria, and Chinese ambitions in the South China Sea.
Any discussion of the crime of aggression will inevitably raise age-old questions about the efficacy of international law. These questions persist in part because the answer is not binary. It is not useful to ask: Does international law matter? Clearly, international law “matters” in that states invest a great deal of resources into navigating it. A better framing of this question is: How does international law matter?
Approaching the broader question from this perspective lends insight into two recent books: The Crime of Aggression: The Quest for Justice in an Age of Drones, Cyberattacks, Insurgents, and Autocrats by Noah Weisbord and The Crime of Aggression, Humanity, and the Soldier by Tom Dannenbaum. Both Weisbord and Dannenbaum are international lawyers, and both authors are candid regarding their broader normative agenda: they see the criminalization of aggression as a means to eradicate war. But the two books are each more than a screed against war. These books also contain an incisive analysis of the process of criminalizing aggression (Weisbord) and a fascinating argument for using this new law to buttress conscientious objection by military personnel in countries engaged in—or about to be engaged in—a war of aggression (Dannenbaum).
While I agree with Weisbord and Dannenbaum in spirit—we all would like war to disappear from the world—my own intellectual starting point is one of skepticism. It is highly unlikely that the criminalization of aggression will lead to the fulfillment of these authors’ normative agendas. While the criminalization of aggression may advance the agenda of eliminating war, there are so many obstacles strewn on this path—many of which, to their credit, Weisbord and Dannenbaum acknowledge, although they do not fully navigate through or around them—that we may have to take many steps backward before we can take any forward. Still, the goal is worthy.
One concern, however, is that an unintended consequence of the criminalization of aggression will be that states may either reframe their behaviors or turn to alternative means to achieve the same end. For example, rather than publicizing an explicit aim to annex Crimea, Russia sponsored a “plebiscite,” leveraging the norm of self-determination to enable territorial acquisition in violation of international norms and laws. If states cannot take territory via armed force, they may turn to other coercive tools, such as demanding territory as payment for overdue loans. There is both older and newer precedent for such actions. In the early twentieth century, the United States justified its occupation of the Dominican Republic by saying that the Dominicans had violated a treaty governing repayment of debt.Footnote 1 More recently, China has taken over ports in Sri Lanka and Djibouti as a result of those countries defaulting on loans.Footnote 2 On one hand, these actions demonstrate the power of international law in shaping how great powers frame critical actions. And, if the alternative strategies that states use include mediation or arbitration, this outcome may well appear pleasingly consistent with international law, especially if states eschew the use of armed force. But the outcome may still be a poor one for people living in these contested territories. And so the criminalization of aggression may tell us more about how states do things with international law than how it constrains states in meaningful ways.Footnote 3 International law can be a weapon of the strong and of the weak. Indeed, it is the strong who are best resourced to fill in the inevitable gaps in the law, to their own advantage.
In the remainder of this review essay, I will focus on three main questions. First, what is the crime of aggression? As this crime is relatively new, an overview is useful, especially in considering who decides whether a particular act qualifies as aggression. Second, why has aggression been criminalized? The move from state to individual responsibility for aggression was most directly preceded by the criminalization of the “big three”—genocide, war crimes, and crimes against humanity—in the Rome Statute, which led to the creation of the International Criminal Court, or ICC. To hold individuals responsible for state actions represents a significant shift from what came before. And third, how effective will the particular strategies suggested by Weisbord and, especially, Dannenbaum be in preventing future wars of aggression? I will consider this last question in light of the relationship between the norm against territorial conquest and the criminalization of aggression. There has been a great deal of concern over the past several years regarding the ability of the norm against conquest to survive; can the criminalization of aggression save the norm?
What is the Crime of Aggression?
Article 6 of the Rome Statute of the International Criminal Court defines “genocide” as “acts committed with intent to destroy, in whole or in part, a national, ethnical, racial or religious group,” including the killing and the forcible transfer of children.Footnote 4 In the statute, “war crimes” include grave breaches of the 1949 Geneva Conventions and the surrounding customary law, including torture, civilian targeting, and intentionally attacking cultural or medical facilities without military objective.Footnote 5 “Crimes against humanity” are “acts committed as part of a widespread or systematic attack directed against any civilian population, with knowledge of the attack,” including murder, enslavement, and forcible deportation.Footnote 6 But, what is “aggression”?
Article 8 bis of the Rome Statute now includes a definition:
“Crime of aggression” means the planning, preparation, initiation or execution, by a person in a position effectively to exercise control over or to direct the political or military action of a State, of an act of aggression which, by its character, gravity and scale, constitutes a manifest violation of the Charter of the United Nations.Footnote 7
The remainder of Article 8 bis expands on this definition, listing invasion, bombardment, and blockade, among others, as potential acts of aggression. But room for interpretation remains. Weisbord and Dannenbaum agree that aggression violates the UN Charter's proscription against “the threat or use of force against the territorial integrity or political independence of any state.”Footnote 8 They also agree that territorial conquest, especially, is likely to qualify as aggression. For Dannenbaum, however, there is a condition: Aggression requires violence, if not fatalities. “Aggression is criminal, not because it violates sovereignty, but because it involves unjustified killing” (p. 34). Given that most—although not all—territorial conquests have involved fatal violence, this condition is typically met.Footnote 9 Territorial conquest remains the clearest case of aggression.
Who, then, decides what “counts” as aggression? This question is critical in itself, but it is also essential both for Weisbord's and Dannenbaum's analyses and for the broader agenda to reduce the incidence of war. The answer, however, remains somewhat equivocal. Just as a territorial conquest resulting in fatalities is one of the few actions that clearly meets their respective definitions of aggression, a determination by the UN Security Council that aggression has occurred would also clear the bar of identifying an aggressive action. As both authors rightly note, however, the Council reaching a consensus on this determination is unlikely to happen. There is considerable overlap between the states most likely to engage in aggressive action and those that hold a veto on the Security Council.
As a practical matter, we would be absolutely certain that a crime of aggression had occurred if a violent territorial conquest took place and the UN Security Council deemed the action to be both aggressive and in violation of the UN Charter. The set of cases likely to meet both these conditions is extraordinarily small. One such case (had aggression been criminalized thirty years ago) would have been Iraq's invasion of Kuwait in 1990.
We are left, then, with a lot of liminal cases. How do cyberattacks fit in? What about drone attacks? What if armed groups that do not self-identify as being employed by a state engage in an apparently aggressive attack? To their credit, Dannenbaum and especially Weisbord acknowledge this uncertainty. Weisbord reports there was some discussion during the Review Conference of the Rome Statute, held in Kampala during 2010, of including cyberattacks in the definition of aggression, but that ultimately the parties decided to restrict the crime to armed attacks (pp. 136, 138). Weisbord, however, is concerned about this omission, arguing that “there are dangers in broadening the definition of the crime of aggression to include new technologies of war and new perpetrators of aggression. But there may be more danger in shrinking away from an untested but vital new legal standard” (p. 143). Dannenbaum does not discuss cyberattacks but does consider the right to disobey in the context of drone warfare, arguing for “an internal imperative to interpret existing law so as to extend certain legal protections to soldiers who refuse to fight in aggressive wars” (p. 266). Both authors view the criminalization of aggression as one step in a progression; as case law and additional legal writing emerge, they expect the scope of what counts as aggression to expand.
History, however, does not always move in one direction. Both Weisbord and Dannenbaum take the reader on a journey from the International Military Tribunal in Nuremberg, where Nazis including Göring, Hess, and von Ribbentrop were convicted of having committed “crimes against peace”; to the UN Security Council deliberations over a definition of aggression in the 1950s (Weisbord, pp. 56–57); to the deliberations over the Rome Statute's definition of aggression in Kampala; to the ICC's seat at the Hague today. Weisbord's account centers on Ben Ferencz, a former Nuremberg prosecutor with whom he developed a friendship. Ferencz was a tireless advocate for making the crime of aggression central to international law, and Weisbord documents his frustrations along the way. Especially striking is Ferencz's decision to revise his will to donate his money to the Holocaust Memorial Museum, instead of his original plan to donate it to the Global Institute for the Prevention of Aggression. He made the change after the very states that had argued for including the crime of aggression during the Nuremberg trials opted out of being held responsible for aggression via the Rome Statute. Ultimately, Ferencz decided it would be more fruitful to include the crime of aggression as a crime against humanity. Weisbord writes: “When I asked Ben about his rationale, he winked and whispered conspiratorially, ‘If you can't go through the front door, go through the back’” (p. 173). Ferencz's case is instructive: there have been victories in this uphill battle, but there have also been significant defeats, and the hill is quite steep.
Why Criminalize Aggression?
Setting aside for a moment the questions of what counts as aggression and who decides, one of the most striking features of the amendment to the Rome Statute is that aggression is now a prosecutable crime. Criminalizing aggression means that individuals, and not (just) states, can be tried and held responsible for committing aggression. This move is part of a larger trend of criminalization in the law of war, where the ICC plays a central role. It is not states, like Libya or Côte d'Ivoire or Serbia, that are now indicted by the court, but individuals, including Abdullah al-Senussi and Laurent Gbagbo.
Part of the theory behind the criminalization of aggression is deterrence. When states stand as litigants or defendants, courts such as the International Court of Justice may rule that a certain set of actions was illegal; some institutions, such as the currently-challenged dispute settlement mechanism of the World Trade Organization, may even be empowered to impose certain penalties. But if individuals know they may be held responsible for their actions, they may well refrain from certain behaviors. Several assessments of the efficacy of the ICC find conditional evidence of the court's deterrent effect, although more so for governments than for rebel groups.Footnote 10 While the evidence is typically indirect, it is consistent with the idea that those who might consider committing war crimes, crimes against humanity, and genocide are increasingly likely to be aware of a new set of consequences from the court for any such actions.
The notion of individual responsibility for criminal behavior as it relates to aggression lies at the heart of Dannenbaum's analysis. The author makes the case that military personnel whose countries are engaging in a war of aggression ought to be able, because aggression is criminalized, to refrain from participating in its commission. “How,” Dannenbaum writes, “can international law hold illegal war to be an ‘accumulated evil’ and yet offer soldiers no right whatsoever to refuse to kill in its service?” (p. 2).
Focusing on the role of soldiers, as opposed to leaders, is a clever move that allows Dannenbaum to expand the ambit of those victimized by aggressive war. It is not just those whose territory and lives are directly threatened by aggressive war who are its victims, he argues, but also the perpetrators forced to commit aggression. Here, Dannenbaum draws heavily on the concept of “moral injury,” which psychiatrist Jonathan Shay defines as occurring when “(1) there has been a betrayal of what's right (2) by someone who holds legitimate authority (3) in a high-stakes situation.”Footnote 11 By forcing soldiers to participate in aggressive war, aggressive states are, he argues, challenging the moral compasses of these individuals in ways that may be injurious: They are inflicting harm upon those whom they instruct to inflict harm upon others by instructing them to inflict harm upon others. This last clause is especially important, as Dannenbaum insists that what makes aggressive war criminal is the killing carried out in its service.
By invoking moral injury, Dannenbaum invites the reader into a set of ongoing debates regarding war-induced psychological trauma. Such trauma has always been a part of war, even going back to ancient Greek understandings, as seen when Homer discusses Achilles's intense reaction to the death of his dear friend Patroclus.Footnote 12 But such trauma has not always been viewed with a clinical eye. As medicine became professionalized in the late nineteenth and early twentieth centuries, physicians diagnosed troops with “nostalgia,” “sunstroke,” and “irritable heart,” and later “shell-shock” in World War I and “combat exhaustion” in World War II.Footnote 13 It was not until Vietnam War veterans and psychiatrists successfully lobbied the American Psychiatric Association that “post-traumatic stress disorder” was finally added to the association's third edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM) in 1980.Footnote 14 The concept of moral injury has appeared on the scene much more recently, and is not included in the DSM.Footnote 15 Psychologists appear to be more likely to adopt the term than psychiatrists. Being neither a psychologist nor a psychiatrist, I will not take a side in that debate. It is worth noting, however, that while the concept serves as a linchpin for Dannenbaum's argument, the diagnosis itself remains somewhat controversial. Thus, a critical pillar of his argument rests on potentially shaky ground.
Moving beyond the ontological status of moral injury, perhaps the more important weakness of Dannenbaum's argument is that the set of actors to whom the central claim of the book applies narrows considerably as the argument and book progress. Dannenbaum is trying to find a solution to the conundrum that the same body of law that has made certain kinds of war illegal also fails to provide an escape clause for soldiers who would prefer not to fight in an illegal war. He diligently considers possible objections to his main argument that soldiers fighting an aggressive war ought to retain a right to disobey. But many readers may find that the objections are ultimately more persuasive than the argument. In part 2 of the book, “Can International Law's Posture towards Soldiers Be Defended?,” Dannenbaum considers the importance of military discipline, the possibility that soldiers may not know that they are fighting an aggressive war, the notion that soldiers have an “associative duty” to their own country and political leaders, and the idea that they may follow a “warrior's code” that precludes disobedience. Dannenbaum deserves credit for considering the objections to his own argument so clearly. And perhaps his argument holds up on a purely legal plane. But in moving from legal theory to the reality of warfighting, this reader stumbled on—and was more persuaded by—precisely the objections he attempts to neutralize.
Consider, for example, Dannenbaum's discussion in chapter 5 of the “epistemic burden” his argument may place upon soldiers. As he acknowledges, soldiers are probably unlikely to be aware that they are prosecuting an illegal, aggressive war (p. 135). Nevertheless, he argues strongly that soldiers ought to treat their own state's claims of being in a just war with skepticism (p. 163). I see two problems with this line of argument. First, even if we agree with Dannenbaum about the epistemic burden soldiers ought to shoulder, typical soldiers are unlikely to do so. While just war theory might be taught in service academies in advanced, industrialized democracies with volunteer militaries, only a small portion of the military attends such institutions. Broader populations—from which the vast majority of the military will be drawn—are typically much less informed about foreign policy issues generally, and likely know little to nothing about just war theory.Footnote 16 Second, by considering objections to his argument sequentially, Dannenbaum misses the broader point that many of these objections form a system. Soldiers’ lack of knowledge or understanding of international law, and the possibility of their states’ violating that law, is reinforced by the need for military discipline, in that soldiers themselves are enjoined to “give their all” to a good fight. Likewise, Dannenbaum pleads for soldiers to take a more “cosmopolitan” worldview (p. 194), breaking their associative bonds to their state. This feels like asking soldiers to be more like international lawyers, an outcome that is not only unlikely but perhaps also undesirable. As the author acknowledges, military discipline is necessary to a functioning military and, until and unless war is permanently eliminated, militaries are still necessary. Thus, Dannenbaum's argument presents a Catch-22.
There are some who may meet his high standards. But they are a small group including very high-ranking military officers and civilian leaders. This is the caste typically indicted by the ICC for war crimes, crimes against humanity, and genocide. Typically, these are also the people giving the orders, raising questions about the relevance of a right to disobey in this context.
Will Criminalizing Aggression Work?
Both Weisbord and Dannenbaum are clear eyed about the challenges of creating a causal chain between criminalizing aggression and decreasing the incidence of aggression. Dannenbaum, in particular, devotes a significant portion of the last sections of his book to developing and thinking through policy proposals that would ensure soldiers’ right to refuse to participate in an aggressive war. Many of these proposals would have to be adopted and implemented at the domestic level, such as the institutionalization of a devil's advocate who would act as a red team, challenging any decision to go to war and the creation of a permanent postwar commission of inquiry. These suggestions are intriguing, and quite possibly good policy even absent the criminalization of aggression. But they would be near impossible to mandate—especially for the most warlike states in the world—precisely because of domestic political imperatives.
Weisbord is less ambitious than Dannenbaum when it comes to policy proposals, focusing instead on liminal cases that may test the ability to judge whether a particular act constitutes a crime of aggression. Both authors consider the changing nature of warfare in this respect. If it is already difficult to judge aggression in traditional state-on-state land warfare cases (such as Russia's invasion of Crimea), how much more difficult will it be to develop and apply standards to humanitarian intervention, drone warfare, and cyberattacks? According to Weisbord: “International law can barely keep up, yet it must” (p. 134).
That international legal scholars are not willing to throw up their hands in the face of apparently insurmountable challenges is both laudable and necessary. Their conviction is backed by substantial evidence that international law “matters,” even if it is not the obvious, blunt evidence that would most easily persuade skeptics. Moving from the jus ad bellum to the jus in bello, the presence of lawyers at the shoulders of war fighters has become increasingly common. And as political scientist and international law scholar Beth Simmons argued during a panel honoring her career and scholarship, perhaps those arguing in favor of international law should not start on the back foot.Footnote 17 Why, in other words, cede the default position to realists and skeptics?
Another way in which we observe international law mattering in war and armed conflict is when belligerents use alternative means to achieve the same ends. This tendency is an important challenge to the criminalization of aggression, raising questions of what these alternative means might be. While international lawyers might prefer mediation and trade, the more likely answer is that states that would prefer to take territory might instead conduct interventions to replace regimes and leaders.Footnote 18 Similarly, outlawing war does not appear to have prevented it, but to have led states to relabel and use alternative justifications for their armed conflicts.Footnote 19
Perhaps these shifts, caused at least in part by international law, are, while not exactly sufficient, sufficiently important to persuade international lawyers that the fight is worth fighting. Weisbord is correct that international law will struggle to keep up (if it can keep up) with the current tangle of international law and emerging technologies such as cyber. Lawyers cannot future-proof war. Being one or even a few steps behind, though, is probably better than conceding defeat altogether.
Bearing this perspective in mind, let us return to two questions: First, if the norm against territorial conquest is eroding, will the criminalization of aggression arrest this erosion? And second, what might the broader effects of the criminalization of aggression be on the incidence of war?
To answer the first question about the future of the norm against territorial conquest, we must consider which states are most likely to engage in such behavior as well as which states have bound themselves to this legal regime. Unfortunately, there is little overlap. As Weisbord documents, countries from the United States to Russia to China, Iran, and Israel have not signed (or have unsigned) the Rome Statute. In addition, what broke the deadlock in including the crime of aggression as an amendment to the Rome Statute was the proposal that there be “an opt-out mechanism whereby the ICC could by default exercise jurisdiction over an alleged aggressor state unless that state had previously opted out of the Kampala amendments” (Weisbord, p. 108, emphasis mine). As of this writing, the International Committee of the Red Cross database reports that 39 states are party to the 2010 amendments, while 123 are party to the 1998 Rome Statute.Footnote 20 Notably, the clear majority of signatories (eighty-one) to the 1998 Rome Statute signed within the first five years of the treaty being open for signature. Not only have significantly fewer states signed the amendment since then but those that have signed are not the likeliest potential violators. Paraguay and Poland seem to have few territorial ambitions today compared to their distant past, and so committing to refrain from territorial aggression is not likely to generate visible behavioral change on their part.
To answer the second question about the broader effects on the incidence of war, we must consider what war looks like today. According to major datasets, most wars today are civil wars. The law of aggression struggles to address intrastate, or noninternational, armed conflict. The definition of aggression in Article 8 bis requires state-on-state violation.Footnote 21 This restriction suggests that in its current form, the crime of aggression cannot be applied to today's most common category of wars.
Digging deeper, however, reveals that plenty of armed conflict between states continues. Because the identification of wars relies on ahistorical battle-death thresholds and medicine has improved, it is likely that the number of wars is undercounted, although we do not know by how much.Footnote 22 Even the conflicts we do know about have more implications for the incidence of interstate war than these data sets admit. Consider the situation in Syria: it is widely discussed as a civil war, but it has become so internationalized that it is, in many ways, a multilateral interstate war between the United States and Russia, Russia and Turkey, and the United States and Syria.
The criminalization of aggression is unlikely to prevent such conflicts, even if its main aim is deterrence. But what it—along with the larger body of international law pertaining to armed conflict—will and can do, and has already done, is to shape such conflicts. Rather than stop them, it limits them. They are fought in the shadow of international law.Footnote 23 The key questions for international legal scholars like Weisbord and Dannenbaum are: What are the effects of these limits? Will this addition to international law mitigate the human costs of war, or will it simply obscure them?
