OVER DINNER AT THE TEHRAN CONFERENCE in 1943, Stalin coolly informed FDR and Churchill of a startling part of his plan for punishing Nazi aggression and deterring future German belligerence, once the war was won: "At least 50,000 and perhaps 100,000 of the German Commanding Staff must be physically liquidated." Churchill, never accused of harboring excessive sympathy for the Nazis, indignantly recoiled from this plan for "the cold-blooded execution of soldiers who had fought for their country." When Stalin insisted that "fifty thousand must be shot," Churchill fired back: "I would rather be taken out into the garden here and now and be shot myself than sully my own and my country’s honor by such infamy." This exchange, recounted in Gary Bass’s Stay the Hand of Vengeance: The Politics of War Crimes Tribunals, underscores one of the central lessons of this important and engrossing book: Although the practice of international politics is predicated largely on the realities of power, domestic political norms inevitably influence the judgments of policymakers. Bass argues that liberal states, governed by the rule of law and dedicated to the protection of individual rights, share an inherent tendency towards legalism—in this context, the belief that war criminals should be put on trial. While the legalistic approach to war crimes presents abundant problems, it also has a singular virtue: In the aftermath of large-scale atrocities, war crimes trials provide civilized states with a principled and constructive alternative to the twin barbarisms of amnesia and vengeance. Stay the Hand of Vengeance focuses on the formidable political obstacles to prosecuting war criminals. Bass, an assistant professor of politics and international affairs at Princeton, examines five episodes in the history of international justice: the diplomacy surrounding the fate of the Bonapartists at the end of the Napoleonic wars, failed efforts to punish German war crimes after the First World War, the abortive prosecutions of Turkish officials implicated in the Armenian genocide of 1915, the trials at Nuremberg after World War II, and the establishment of the International Criminal Tribunal for the Former Yugoslavia at the Hague in 1995, which the author covered as a correspondent for the Economist. Bass does a particularly good job of demonstrating the contingent nature of history. In his chapter on Nuremberg, for example, we learn that the decision to subject Nazi leaders to bona fide trials was far from inevitable. Indeed, the Allies—less than a year before the end of the war—had formally committed themselves to a policy of summary execution for all the top German officials upon capture. According to the Morgenthau Plan, initialed by Roosevelt and Churchill in September 1944, the "arch criminals" were to be put to death by firing squad as soon as they were apprehended and identified. But a fortuitous convergence of circumstances led this plan to be abandoned. Although polls indicated strong popular support for summarily executing top Nazi leaders, there was considerable public opposition to an unrelated provision of the Morgenthau Plan, calling for the pastoralization of Germany. When that provision was leaked to the press, the Morgenthau Plan collapsed, allowing the proponents of trials to seize the initiative and modify Allied plans for punishing Nazi leaders. The most determined and articulate advocate of legalism in the American government was Henry Stimson, Roosevelt’s secretary of war. In a memorandum to the president, Stimson argued that Allied governments should adhere to a well-defined procedure for dealing with Axis war criminals. "Such procedure," he wrote, "must embody, in my judgment, at least the rudimentary aspects of the Bill of Rights, namely, notification to the accused of the charge, the right to be heard and, within reasonable limits, to call witnesses in his defense." It might not be practical to apply the full range of domestic legal principles to such trials, Stimson acknowledged, but "the very punishment of these men in a dignified manner consistent with the advance of civilization, will have all the greater effect upon posterity." Stimson’s memorandum outlined the essential parameters of the scheme that would become Nuremberg. In proposing to grant accused war criminals the core safeguards of the Bill of Rights, Stimson was not revealing a latent sympathy for Axis leaders; instead, he was affirming his fidelity to the principles of the U.S. Constitution and indicating his belief that we define ourselves in part by how we treat our enemies. Like Churchill’s solicitude for his own and his country’s honor, Stimson’s commitment to due process was incomprehensible to Soviet leaders, whose desire for vengeance, Bass notes, was "utterly unhindered by liberal legalistic norms." Bass’s scholarship will challenge widely divergent views about war crimes tribunals. Even the most enthusiastic legalists, for example, will take away from this book a modicum of sympathy for the argument that national governments must sometimes subordinate the pursuit of justice to wider political considerations. Chief among these is the concern that arrests and prosecutions may generate a nationalist backlash in the countries whose officials and soldiers are being put on trial. Since fragile peace agreements are easily undermined by resurgent nationalism, statesmen will sometimes be confronted with an uncomfortable choice: to let war criminals go free for the sake of peace and reconciliation, or to pursue justice at the possible expense of exacerbating political antagonisms and perpetuating armed conflict. Any who doubt the potentially destabilizing consequences of war crimes prosecutions might consult Bass’s treatment of Allied policy towards Germany in the aftermath of the First World War. The Allied governments accused Germany of a wide range of offenses, including unrestricted submarine warfare, brutal treatment of prisoners, invasion of neutral Belgium, and instigation of the war itself. Britain and France, whose losses during the Great War far outstripped those of the United States, were especially eager to prosecute the German kaiser, Wilhelm II, for the novel crime of aggressive warfare. When David Lloyd George was informed that waging war was "the prerogative of the right of all nations from the beginning," and that prosecuting the kaiser would thus be akin to trying Alexander the Great or even Moses, the impassioned prime minister retorted, "I am not sure that they also ought not to be brought to justice!" As it turned out, the idealism underpinning this crusade for justice collapsed ignominiously in the face of political realities. William II fled to Holland at the end of the war, and the Dutch government rejected repeated Allied demands for his extradition. Meanwhile, Germany—defeated but not occupied—declined to deliver German officials to an international tribunal. Unwilling to resort to force, the Allied governments reluctantly agreed to a scheme whereby certain German soldiers and officials accused of war crimes were tried by a German court in Leipzig. But the court proved predictably inhospitable to British and French notions of justice and either acquitted suspects or imposed light sentences on the grounds that the accused were merely following orders. Both the failure to bring German war criminals to justice and the trials themselves adversely affected the political stability of postwar Germany. As Bass writes, "In the chaos of Weimar Republic politics, Göring first encountered Hitler at a rightist rally against French demands for the trial of German war criminals." The Leipzig debacle reminds us of the pitfalls of legalism. This is especially useful in that, as Bass notes, present-day scenarios for punishing war criminals resemble Leipzig more than Nuremberg in certain respects. On the other hand, even self-styled realists may be dismayed to learn that liberal states have often sacrificed the pursuit of justice to parochial interests. When nationalist Turks took twenty-nine Britons hostage in the aftermath of the First World War, for example, the British government, fearful for the lives of the hostages, released from custody all Turkish officials accused of war crimes. From the government’s perspective, the lives of a few dozen British citizens were more important than Britain’s wartime promise to prosecute the architects and agents of the Armenian genocide. As a member of the British Foreign Office breezily admitted, "It is in a measure yielding to blackmail but seems justified by present circumstances." Bass argues that the reluctance of national governments to endanger the lives of their soldiers for the sake of international justice is the single greatest obstacle to prosecuting war criminals. Since even liberal states are effectively held hostage to relatively narrow political interests, some proponents of international justice vest high hopes in the creation of a permanent international criminal court for punishing war crimes and crimes against humanity. Although a plan to establish such a court was approved by a U.N. conference in Rome—over the objections of the United States—in July 1998, Bass has little to say on the subject of a permanent international court, which presents its own dangers. Bass borrows the title of his book from an opening statement at Nuremberg, presented by the American Justice Robert Jackson: "That four great nations, flushed with victory and stung with injury, stay the hand of vengeance and voluntarily submit their captive enemies to the judgment of the law is one of the most significant tributes that Power has ever paid to Reason." Bass is an ardent legalist, and, given the successful outcome of the Nuremberg trials, it is understandable that legalists should point to that tribunal as an example of international justice done right, and therefore as a precedent for future prosecutions. Yet one of the central insights of Bass’s book is that Nuremberg was successful largely because the circumstances were not ordinary: The Allies did not confront the usual political obstacles to prosecuting war criminals. Their occupation of Germany made it relatively easy to apprehend Nazi officials. Unfortunately, this analysis suggests that the Nuremberg precedent is of diminished relevance to the contemporary scene, characterized as it is by limited war in pursuit of objectives markedly more modest than unconditional surrender. Under circumstances like those of the Persian Gulf War or the war in Kosovo, it is exceedingly difficult to arrest indicted war criminals; and indictments by themselves are likely only to further radicalize the embittered populations. It may be sobering to learn that mankind’s most successful experiment in international justice was made possible by a historical anomaly. But however disheartening the record, clear thinking about political realities is the indispensable foundation of any sound program of international justice. After several years working as a journalist in Washington, D.C., Amit Agarwal begins law school this fall.