War and Treaties in the Constitution

Every year, schools and government agencies join the nation in observing Constitution Day and Citizenship Day the week before and after Sept. 17, the anniversary of the signing of the Constitution. Federal courts participate by offering educational resources and experiences in their communities. Below, UNH associate professor Will Smiley shares a piece entitled "War and Treaties in the Constitution." To read this piece and other essays by UNH faculty around Constitution Day, click here.

We tend to think about the Constitution as a domestic, American document: it sets the structure of the federal government; it allocates power between the federal government and the states, and between the president, Congress, and judiciary; and it-or rather, its amendments-guarantee individual rights. But as scholars have shown-including UNH's own Lige Gould-the Constitution, like the Declaration of Independence, was always intended also as an international document. The Declaration of Independence had proclaimed that the United States was taking its place "among the powers of the earth," and the Constitution was meant to show the British, Spanish, and French Empires that the U.S. deserved that place. The mechanisms by which it did so are clever, and worth recalling as we consider current questions.

In the eighteenth century, there were two ways that states could relate to each other: through treaties, or through war. Both were legal instruments. A treaty was a promise by a state that it would act in certain ways in the future-that it would lower tariffs, or send military aid, or allow ships to pass. And war was the way to enforce treaties. If one state harmed another, by taking its territory or breaking promises, then the victim's appropriate response was to declare war. That would dissolve all treaties and obligations. Territory, ships, or goods could be seized as compensation for injuries. God would decide which side's cause was most righteous, by making that side the victor. Then a new treaty could be signed to end the war, give the victor the compensation he deserved, and restore friendly relations.

To show that the U.S. deserved its place in the world, the Constitution would have to ensure all thirteen states would cooperate closely to uphold treaties or to fight wars, as they had during the Revolution (but had failed to do in the years since). If the federal government made a trade treaty with Spain, or borrowed money from Britain, all the states would honor that. And if Georgia was threatened by the Royal Navy or the Bourbon army, the federal government would respond, with all the states behind it.

How could the Framers be sure that states would all come together to honor treaties? And how could foreign states be sure that the new nation was, in Gould's words, "treaty worthy"? Why would the King of France, Britain, or Spain sign a treaty with a president who would only be in office for four years, and who might be replaced by his bitter enemy, with entirely opposing policies, after the next election? The key was to show that the government would honor promises made by previous presidents, not just the current one. So, the Constitution provides that states may not enter into treaties on their own (Art. I Sec. 10). Only the president may do that, but not on his own: a treaty does not become valid until ratified by two-thirds of the Senate (Art. II, Sec. 2). This means that foreign powers can have confidence that a ratified treaty does not just reflect the personal promise of one president, but a broad commitment, from the whole U.S. political system, to obey the treaty. (To get a two-thirds vote today, for example, would require the buy-in of both political parties.) And once ratified, a treaty becomes part of "the supreme Law of the Land," just like the Constitution itself (Art. VI)-so it would be enforced by U.S. courts. And treaties could-probably-only be terminated with the consent of Congress. (The Constitution, perhaps due to an oversight, did not specify how to withdraw from treaties. Until the twentieth century, the consensus was that this required congressional consent. Since then, presidents have made withdrawals unilaterally.)

On the flip side, how could the Framers be sure that states could come together in wartime? And how could foreign states be sure of it? If Spain, or Britain, thought the United States would not hold together, then why not try to conquer Georgia, or Maine? Or less drastically, a foreign state might violate its treaty obligations if it thought the U.S. could not effectively declare war to enforce its rights-remember that war was the legal mechanism used to enforce treaties. Again, the Constitution provided a clever mechanism. The president was to be Commander-in-Chief of the U.S. Army and Navy, and also of the states' own militias (Art. II, Sec. 2)-ensuring a quick and unified U.S. military response to any foreign invasion.

However, only Congress could start a war, or sustain one: only it had the power "To declare War…To raise and support Armies…To provide and maintain a Navy…To provide for calling forth the Militia" (Art. I, Sec. 8). Such actions would require majorities in both the House of Representatives and the Senate.

This clause was vital to the whole system. It was important that the U.S. be able to go to war, to defend its treaty rights, but also that it not be too easy. Learning from their studies of ancient Greece and Rome, the Framers feared the power a president could attain in wartime, with armies and powers at his command that would be absent in peace. But there is another aspect here: a war, like a treaty, was a consequential action on the international stage. It would be dangerous for the U.S. to take such an action without the whole nation being unified. So, treaties required Senate ratification, to make sure they were products of broad consensus instead of the whim of one man (or woman). Likewise, the need for a majority vote in both houses to start a war meant that the country could only enter into a war if it was unified behind the cause. To do otherwise would risk military and political disaster.

I leave it as an exercise for the reader to determine how well our current practice, and our recent past, reflects these arrangements.

Sources and Further Reading:

Armitage, David. "The Declaration of Independence and International Law." William & Mary Quarterly 59, no. 1 (2002): 39-64.

Bradley, Curtis A. "Treaty Termination and Historical Gloss." Texas Law Review 92 (2014): 773-835.

Golove, David M., and Daniel J. Hulsebosch. "A Civilized Nation: The Early American Constitution, the Law of Nations, and the Pursuit of International Recognition." New York University Law Review 85, no. 4 (2010): 932-1066.

Gould, Eliga H. Among the Powers of the Earth: The American Revolution and the Making of a New World Empire. Harvard University Press, 2012.

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

Moynihan, Daniel Patrick. On the Law of Nations. Harvard University Press, 1990.

Whitman, James Q. The Verdict of Battle: The Law of Victory and the Making of Modern War. Harvard University Press, 2012.