Why Federal Courts Apply the Law of Nations Even Though it is Not the Supreme Law of the Land

We are grateful to the judges and scholars who participated in this Symposium examining our book, The Law of Nations and the United States Constitution. One of our goals in writing this book was to reinvigorate and advance the debate over the role of customary international law in U.S. courts. The papers in this Symposium advance this debate by deepening understandings of how the Constitution interacts with customary international law. Our goal in this Article is to address two questions raised by this Symposium that go to the heart of the status of the law of nations under the Constitution. The first question is whether the Constitution adopted the law of nations (or some subset of it) as the supreme law of the land. This fundamental question has profound implications for the proper role and status of customary international law in the U.S. federal system. The second question is whether the Constitution’s allocation of certain powers to the political branches of the federal government has any bearing on the power or obligation of federal courts to apply the law of nations. Resolution of this question is particularly important if one concludes, as we do, that the Constitution did not adopt the law of nations itself as supreme federal law. Regarding the first question, Professors David Golove and Daniel Hulsebosch echo the modern position that the Constitution adopted the law of nations as supreme federal law and thus assigned primary responsibility to courts, rather than the political branches, to comply with the law of nations. Their evidence for this proposition, however, is unpersuasive. Although they present ample evidence that members of the founding generation understood the law of nations to form “part of the law of the land” or “part of the law of the United States,” they present no evidence that the founders understood the Constitution to adopt the law of nations as the “supreme Law of the Land,” enforceable by courts not only in preference to contrary state law, but also in preference to contrary executive action and possibly even acts of Congress. By design, the Supremacy Clause recognized only three sources of law as “the supreme Law of the Land” — the “Constitution,” “Laws made in Pursuance thereof,” and “Treaties.” Under the Constitution, each of these sources of law can be adopted only with the participation and assent of the Senate (designed to represent the states) or the states themselves. This veto was the price of supremacy exacted by the states during the drafting and ratification of the Constitution. Professors Golove and Hulsebosch acknowledge that the Supremacy Clause did not make the law of nations the supreme law of the land, and they identify no other constitutional provision giving it that status. Regarding the second question, whereas Professors Golove and Hulsebosch overstate the status of the law of nations as supreme federal law, they undervalue the relationship between the law of nations and the Constitution’s allocation of powers. Specifically, they contend that the Constitution’s allocation of power to the political branches to recognize foreign nations was historically irrelevant to the obligation of U.S. courts to uphold the rights of foreign nations under the law of nations. In the twentieth century, the Supreme Court has expressly relied on recognition to uphold the sovereign rights of foreign nations. Such reliance is largely consistent with historical understandings and practice. Because early federal courts applied the law of nations as general law, they had little need in most cases to spell out the precise relationship between judicial adherence to the law of nations and the exclusive powers of the political branches over war, foreign relations, and recognition. But background understandings of the law of nations suggest that the Constitution’s exclusive allocation of these powers to the political branches required courts — in the absence of contrary instructions from the political branches — (1) to respect rights of recognized foreign nations under the law of nations and (2) to refrain from enforcing rights of the United States against other nations. Early Supreme Court opinions also suggest that the judiciary’s failure to uphold the rights of foreign nations under the law of nations, and the judiciary’s unilateral enforcement of U.S. rights against other countries, would usurp the exclusive constitutional powers of the political branches over these matters. In some early cases, when necessary to resolve the dispute at hand, the Court alluded to these points explicitly. The Court’s increased reliance on the Constitution’s allocation of foreign relations powers to justify these same practices in the modern era rests on a foundation established by early precedent in light of the Constitution’s original design.