The Internationalists: How a Radical Plan to Outlaw War Remade the World by Oona Hathaway and Scott J. Shapiro is a book I learned a lot from even as I disagree with its premises. The authors consider our current system of international law to be mostly a positive thing, which they attribute to the 1928 Pact of Paris (also known as Kellogg-Briand). The basic idea of this agreement was to outlaw offensive warfare by declaring that countries needed to refer their disputes to arbitration and that all conquests done after 1928 were not to be recognized by the international community. (By declaring that only future conquests were illegitimate, the pact bypassed the issue of the British and French empires, which were created precisely through the sorts of actions that were now supposed to be illegal.) By implication, the pact granted relevance to international opinion. Now all wars involved the international community as other countries needed to decide whether the agreement had been violated and whether they could recognize new realities on the ground.
The practical implications of this agreement could be seen in the 1931 Japanese invasion of Manchuria. U. S. Secretary of State Henry Stimson refused to recognize Japan's control over Manchuria or the newly proclaimed State of Manchukuo. This struck the Japanese as rather hypocritical as it was hardly obvious how Japan's behavior in Manchuria was any worse than what European imperialists had been doing as a matter of course. Furthermore, Japan still bore bitter memories of Commodore Matthew Perry's diplomacy at gunpoint. Japan's mistake was that they invaded Manchuria three years too late; now there was a new set of rules.
To be clear, as the authors note, the Pact of Paris did not stop Japan nor any of the other acts of Fascist aggression leading up to World War II. Furthermore, even the judges at Nuremberg ignored an attempt to use the Pact of Paris as a basis for prosecuting Nazi defendants. The idea was that since the actions of Nazi Germany were illegal according to the Pact of Paris, the defendants had no immunity against prosecution. What the authors want to argue is that, despite spending years as mostly a dead letter, in the post-war world, the logic of the Pact of Paris was taken up and became the basis for modern international law. For example, the pact's rejection of territorial expansion meant that, with the notable exception of Poland, international borders changed remarkably little after World War II, particularly if you compare it to World War I. Since World War II, borders have been rather stable and there have been few wars of territorial conquest. It is no longer worth it to conquer territory if the international community will not recognize it.
For a book that is supposed to be about twentieth-century legal thought, the authors spend quite a lot of time on early modern history. As a foil to modern international law, they set up the seventeenth-century scholar Hugo Grotius. I have long considered Grotius to be one of those proto-Enlightenment thinkers who have been unfairly ignored by the general public. In reading this book, I found myself agreeing with Grotius and thinking that the world would be a much better place if we rejected modern international law and went back to something more along the lines of early modern international law as embodied by Grotius.
Grotius' seventeenth-century Europe saw the emergence of states as distinct from Christendom or a personal monarchy, with Grotius' native Dutch Republic taking the lead, even as we are still a long way from secular democracies in the modern sense. For Grotius, the state was its own moral entity, distinct from its leaders or population. As such, while Grotius believed that states needed to justify their decisions to go to war, its leaders, population, and even the international community were exempted and even, in practice forbidden, from considering whether the state's justifications were valid. Soldiers fighting a war still had to obey the laws of war and refrain from committing war crimes as these did nothing to bring the war to a conclusion. That being said, they were not asked to be lawyers and historians qualified to evaluate whether their government was in the right. Furthermore, Grotius' version of international law had no third-party enforcement. States that allowed their soldiers to commit atrocities invited retaliation by the opposing army. Finally, since other countries were not expected to be knowledgeable enough to have an opinion about the morality of any particular foreign war, once a treaty was signed, that was the end of the matter. If a country managed to win a war and forced the defeated country to sign away territory in a peace treaty, the new borders must now be accepted by all.
What Hathaway and Shapiro dislike about Grotius is that his type of international law opened the door for all kinds of wars of expansion, with states coming up with factitious reasons to go to war without any oversight and then holding on to their ill-gotten gains. The authors point to the young Grotius working as a lawyer for the Dutch East India Company and defending the seizure of a Portuguese ship, seeing in this the foundation for his later work on international law.
One of the examples the authors give of countries fighting according to Grotius' international law was the Mexican-American War of 1846-48. President Polk could declare war against Mexico over claims of unpaid debts that few people took seriously even at the time. American soldiers were required to obey their orders and not consult their consciouses. Similarly, the international community had no mandate to consider whether this was a war of aggression and if they had an obligation to intervene. Finally, the morality of Polk's declaration was forever placed beyond challenge by the Treaty of Guadalupe Hidalgo, which gave the American Southwest to the United States. Whether or not the United States had the right to conquer this territory, it now belonged to the United States and attempting to take it away would violate international law.
Surprisingly enough, Grotius had a direct influence on Japan and its justifications for imperialism. In the nineteenth century, Japanese scholars started reading Grotius as a blueprint for how to operate in the world. Japan was emerging into a world dominated by European countries who had certain understandings between themselves. If Japan was going to be a great power they needed to know what these rules were. Grotius, as the father of international law, seemed to offer them the key. This seemed to work until they invaded Manchuria and they discovered that the rules had changed.
For all their criticism of Grotius, Hathaway and Shapiro fail to consider the practical benefit of Grotius' willingness to place the question of whether a state was right to go to war in a kind of moral black box. By not demanding that citizens have the right answer as to the morality of their country's war, we protect those citizens. Their country might be in the wrong, but we are still going to grant rights to the soldiers fighting this immoral war and even the politicians. This facilitates limiting the scope of the war and working toward a peace treaty. Allowing even immoral treaties forced upon a weaker power to stand also helps to support peace. We do not want to be refighting every morally questionable war, whether the Mexican-American War or any other war.
Considering the amount of knowledge required to settle historically based disagreements between countries, modern international law seems designed to promote a regime of international elites, who are simply going to confirm their prejudices as to which country is right in any given dispute. The use of the International Criminal Court against Israel is a good example of this. Those making the case seem willfully blind to the question of what Israel needs to do in order to avoid another October 7th. The moment we consider military necessity, the whole trial would have to be postponed until after the war when Israeli generals would be free to answer questions about their decisions without compromising ongoing military operations.
Hathaway and Shapiro actually discuss the Israeli-Palestinian conflict as an example of the limits of the Paris Peace Pact. Neither the State of Israel nor Palestine existed in 1928 so the pact is useless for deciding borders. Worse, because the pact does not allow for conquest, it leaves us without a framework for a treaty. Any borders agreed to would be open to future challenges as the product of a forced treaty and, therefore, illegitimate. Having Grotius as our model for international law would allow the Palestinians to say that Israel wronged us but we lost the war and now need to move on and make peace.
