war on the rocks

The False Dawn of International Law: Revisiting the Doomed Kellogg-Briand Pact

January 15, 2018

Oona Hathaway and Scott Shapiro, The Internationalists: How a Radical Plan to Outlaw War Remade the World (Simon and Schuster, 2017).

In the long list of diplomatic failures, the Kellogg-Briand Pact seems like a fitting if harmless entry. In 1928, nearly all the nations of the world signed an agreement to outlaw war as a tool of statecraft. Whether it was spectacularly bad timing or well-meaning hubris, things did not go according to plan. Instead of witnessing the end of warfare, the world entered a period of intense conflict that culminated in the cataclysm of World War II.

But after its demise, the Pact took on another life — as a cautionary folk tale among scholars of global politics. In its naive arrogance, it came to represent everything that was wrong with the idealism of the interwar period. For the realists, its utopian urges fundamentally misunderstood the nature of power, leaving it unable to deal with threats like Adolf Hitler. As the distillation of this mindset, the Pact was either meaningless or made things worse.

Wrong, say Oona Hathaway and Scott Shapiro. The conventional story has it exactly backwards: While it came up short at the time, the Pact was the single most important factor in producing an unprecedented period of stability after 1945. Without the Pact, other factors key in shaping postwar peace, like globalization or nuclear weapons, would not have been possible. In the language of social science, the Pact is the main independent variable and the necessary prerequisite for peace.

Is the book an enjoyable and worthwhile read? Yes. Is it convincing in its main argument? Not at all.

The Internationalists is best when chronicling the huge set of characters who shaped the evolution of legal doctrine over the centuries. There’s the brilliant but apparently insufferable Hugo Grotius, who becomes the father of international law by writing a text that defends corporate raiding. Grotius was hired by the East India Company to justify his cousin’s robbery of a Portuguese carrack. In response he produced a 500-page treatise that combined just war theory with anti-Portuguese slurs and set off the modern trajectory of international law. Cosmopolitan legalism was therefore born out of parochial, hypocritical, and nationalistic interests — a place where its critics say it remains. There is also Salmon Levinson, a Chicago lawyer and the book’s underdog, who plays a key but often forgotten role in shaping the Stimson Doctrine. Most intriguing is the role of American isolationists like William Borah, who did not renounce international law but sought to mobilize it for their own purposes. The book’s plentiful endnotes contain interesting digressions on letters of marque and the average size of nations. In short, as a story of an idea and a wide-ranging legal history, the book is a success.

The trouble comes when the authors turn to the central thesis — that the Kellogg-Briand Pact was not only “among the most transformative events of human history” but also the main cause of great power peace since 1945.

As evidence, they point to a dramatic decline in the frequency of interstate war and the near-disappearance of territorial conquest. However, as the authors note, the breakpoint in these trends happens not in 1928 but in 1948. By their own calculations, the rate of conquest between 1816 and 1928 remains about the same as the 20 years after the Pact — 1.21 and 1.15 conquests per year, respectively (assuming that such a crude measure, which doesn’t capture the intensity or the scope of conflicts, is even indicative of overall trends). The big dip comes after 1948, when the average drops to 0.26 conquests per year. (For a detailed analysis, see the review by Michael Glennon in Lawfare.)

In short, the authors’ own data point to other factors starting the process: the role of nuclear deterrence, international institutions, the pacifying effects of globalization, and hegemonic management of the international system. But acknowledging them is pretty much where the book stops. Empirically, there is no attempt to control for these influences in any statistical test or to process-trace their effects in any detail. Theoretically, there is no attempt to integrate these factors into a cohesive explanation of post-war peace. The authors should be commended for making a bold case for a previously ignored factor, but in doing so they make little effort to contextualize the argument. The book concedes that international law alone cannot explain everything, but says little about what that means for their explanation. How much do these other factors matter, and under what conditions? How might they interact or reinforce each other? These questions are not asked, let alone answered.

Instead, the book simply asserts that these explanations are incomplete because they can’t explain why most of the post-war borders “snap back” to the boundaries that existed in 1928. In other words, the violence of 1928 to 1945 does not detract from their argument. Once war was over, all the conquests that took place in the intervening years were reversed. And the fact that territories reverted to 1928 borders shows that the Pact was the decisive and necessary precedent for the disappearance of conquest.

But the fact that borders snapped back to 1928 doesn’t tell us much about the causes of post-1945 peace. All it suggests is that the ideas (or at least, the maps) embodied in the Pact were preserved and used by the victors for building the postwar order. Even if the Pact explains the details of postwar territorial adjustments, that doesn’t mean it also explains the peace that followed. For that, alternative and more plausible explanations exist that the book simply does not engage.

Moreover, the Pact being a focal point doesn’t mean it was a necessary prerequisite for the peace that followed. It’s not surprising that the victors drew upon legal precedents when rebuilding the global order. In fact, it would be surprising if they didn’t rely on past attempts like the Pact. But were the conquests of previous years reversed because of the Pact, or because the conquering states were defeated? And if the Axis had won, would the Pact have made any difference?

In addition, to say that the Pact was a necessary prerequisite is to suggest that without it, the United States would have been unable to construct a global order after its victory. None of these are plausible counterfactuals. That doesn’t mean international law is meaningless. It can take on a life of its own, and change states’ decisions and even the incentives that frame those decisions.

But here the book mistakes the coffin for the murder weapon. Just because the Pact framed some of the decisions for burying the old order in 1945 doesn’t mean it helped to kill it. And it certainly doesn’t mean it helped to preserve the peace that followed.

The tensions in the argument become especially visible in the conclusion, where the book laments the inevitable decline of the liberal order (a phrase that will soon be contractually obligated in every book on global affairs). But if international law has triumphed for reasons unrelated to globalization or American power, why is it so fragile now that the United States is withdrawing? The book offers a solution: “The success of the system depends on the willingness of the United States to continue to play a central role in maintaining the legal order in the face of these many challenges.” It’s odd but also indicative that American hegemony — the very thing that was secondary to creating and maintaining the global order — now becomes crucial for rescuing it.

And if the “might is right” doctrine is dead, as the book asserts, then we would expect to see few military invasions of the weak by the strong except as permitted by international law. But in fact, great powers have continuously invaded the sovereignty of other states, often against the wishes of the so-called international community. Wars of conquest may have disappeared after 1945 (even if we ignore the 1950 takeover of Tibet, as the book does, or Stalin’s takeover of Eastern Europe). Yet wars of aggression have not, even as the justifications for them have taken on a different tenor, and even as the label of war is replaced by more anodyne terms like intervention.

What is the purpose here? Is this flashy revisionism for its own sake? I don’t think so. The authors seem sincere in their belief in both the power and the value of international law. They appear to see the Kellogg-Briand Pact as a sort of shining beacon, preserved by hopeful reformers in the midst of darkness, lit anew to brighten the postwar world. Throughout the book there is an implicit assumption that laws drive politics — and that if we get the laws right, the politics will follow. What’s missing is the acknowledgement that the reverse is often true — that politics can determine whose rules are followed, and even which rules are conceivable. Here the book recapitulates many of the same shortcomings that E.H. Carr outlined in his case against utopianism nearly eight decades ago. Unfortunately, in many ways it does not move beyond them.

The facile counter-argument would be that realist thinkers like Carr were limited in their understanding of international law. But it’s not that the book needs to pay more obeisance to realist factors like hegemony or liberal factors like the spread of democracy. (The realist bogeyman lurks in the background, though luckily the book does not resuscitate those hoary debates.) More fundamentally, the argument is unconvincing from the standpoint of basic causal inference. There is no attempt to seriously examine other explanations, to anticipate possible objections except in the most perfunctory way, or to consider the secondary implications of the argument itself. In the end, the book provides astonishingly thin evidence for an astonishingly strong conclusion.


Seva Gunitsky is an associate professor of political science at the University of Toronto. He is the author of Aftershocks: Great Powers and Domestic Reforms in the Twentieth Century (Princeton University Press, 2017), recently named one of the “Best Books of 2017” by Foreign Affairs. Follow @SevaUT.