The constitutional power to interpret international law.

• Author: Paulsen, Michael Stokes

FEATURE CONTENTS INTRODUCTION I. THE FOG OF INTERNATIONAL LAW A. The Trouble with Treaties B. Executive Agreements C. "Customary International Law" II. THE POWER TO SAY WHAT INTERNATIONAL LAW IS (FOR THE UNITED STATES) A. Congress's Power To Interpret and Apply International Law as Domestic U.S. Law B. The President's Power To Interpret and Enforce International Law C. The U.S. Judicial Power To Interpret International Law for the United States III. THE RELEVANCE AND IRRELEVANCE OF INTERNATIONAL LAW TO UNITED STATES LAW AND THE WAR ON TERROR A. The Power To Initiate War-Jus ad Bellum B. The Power To Wage War-Jus in Bello CONCLUSION INTRODUCTION

"International Law" is all the rage. The subject is one of the hottest courses in the law school curriculum. And it is frequently the focus of great public attention, given events in the post-9/11 world. Has particular conduct by the United States "violated international law"? Is some contemplated--or completed--course of conduct "consistent with international law"? These are very much the questions of the day.

But what is the force of international law as a matter of the constitutional law of the United States? To what extent is international law, whatever its content and the method for making or discerning its content, binding as U.S. law? More pointedly, to what extent is international law not recognized as authoritative by the U.S. Constitution? Just as importantly, who determines the force and content of international law-who interprets and applies it, authoritatively, for the United States? May international bodies define legal norms for the United States? Is interpretation of international law's commands uniquely within the province of international tribunals? Or, quite the reverse, is it "emphatically the province and duty" of U.S. officials to say (for the United States) "what the law is," (1) including international law to whatever extent it is thought binding on American policymakers? If international law is, in some instance, in conflict with other commands or powers of the U.S. Constitution, how should such conflicting legal requirements and obligations be reconciled by courts and policymakers acting on behalf of the government of the United States?

These, too, are the vital questions of the day. Yet they are surprisingly undertheorized. These fundamental constitutional questions concerning international law are often shortchanged by international law scholarship, which frequently brushes by them, blithely assuming that the United States is bound by international law if that is what the regime of international law says, without giving serious attention to the acute U.S. constitutional problem posed by such an assumption. In part, this is attributable to the parochialism of academic legal specialties. "International Law" scholars form their own niche--clique, even--within the academy. Few international law scholars are also serious U.S. constitutional law scholars. The reverse is also the case to a large extent (though more and more constitutional law scholars have gravitated to interests in the field of international law). (2) The result is a kind of segregation of legal thinking. International law has become, ironically, intellectually isolationist and parochial, excluding critique from a U.S. constitutional law perspective and declining (in the main) to engage with it.

My thesis in this Essay is a straightforward one and, from the perspective of basic postulates of U.S. constitutional law, should be an obvious one: for the United States, the Constitution is supreme over international law. International law, to the extent it issues determinate commands or obligations in conflict with the U.S. Constitution, is unconstitutional. Where there exists a conflict between the U.S. Constitution's assignments of rights, powers, and duties, and the obligations of international law, U.S. government officials must, as a matter of legal obligation, side with the Constitution and against international law, because the Constitution, and not international law, is what they have sworn to uphold. As a matter of domestic constitutional law, U.S. law always prevails over inconsistent international law.

Not all international law is of such description, of course. There is no necessary conflict between U.S. law and international law. To the contrary, some international law is explicitly made part of U.S. law by the terms of the Constitution itself. Article VI of the Constitution, for example, makes treaties to which the United States is a party part of "the supreme Law of the Land." (3) Other provisions of the Constitution appear to authorize various government actors to use international law as a predicate for the exercise of certain powers or duties. But in such cases--just as with the case of international law norms that might conflict with U.S. law--the Constitution remains supreme in determining the content and force of international law for the United States.

The constitutional supremacy thesis has an important corollary: as a matter of U.S. constitutional law, the constitutional power to interpret, apply, and enforce international law for the United States is not possessed by, is not dependent upon, and can never authoritatively be exercised by actors outside the constitutionally recognized Article I, Article II, and Article III branches of the U.S. government. The power to interpret and apply international law for the United States is a power vested in officers of the U.S. government, not in any foreign or international body. As a matter of U.S. constitutional law, the United Nations does not and cannot authoritatively determine the content of international law for the United States. As a matter of U.S. constitutional law, the International Court of Justice (ICJ) does not and cannot authoritatively determine the content of international law for the United States. As a matter of U.S. constitutional law, no international body authoritatively determines the content of international law for the United States.

Rather, the power to interpret international law for the United States is a power distributed among the three branches of the U.S. government, in a manner determined by the Constitution's separation of powers. The Congress interprets and applies international law for purposes of exercising its legislative constitutional powers to define and punish offenses against "the Law of Nations," (4) thereby enacting (or declining to enact) legislation for carrying into execution treaties of the United States, and for purposes of exercising its autonomous constitutional judgment with respect to the decision whether or not to initiate ("declare") a state of war. (5) The President interprets and applies international law for purposes of exercising the Article II executive power to conduct the nation's foreign relations and the constitutional powers of the President as the nation's military Commander in Chief. And the courts interpret and apply international law for purposes of exercising their adjudicative constitutional powers with respect to lawsuits presenting questions of interpretation of treaties and other matters of international law.

These interpretive spheres overlap to some degree. But there are also areas of autonomous power for each branch. Each branch has a limited, exclusive power to determine the content of international law for purposes of its own powers. In accordance with the Constitution's scheme of separation of powers, none of the branches is literally bound by the views or actions of the others. And in accordance with the Constitution's exclusive assignment of U.S. lawmaking, law-executing, and law-adjudicating functions to actors designated by the Constitution, none of the branches is bound in any way by the views or actions of non-U.S. actors.

Part I of this Essay, to which I give the Clausewitzian subtitle "The Fog of International Law," comprehensively addresses the surprisingly elusive (to most modern international law scholars) question of the status of international law as a matter of U.S. law. Confusion about the force of international law within the U.S. legal order leads to further confusion and unclear thinking about who possesses the power to interpret and apply international law provisions and norms for the United States. I argue, first, that the Constitution mandates as a matter of U.S. domestic law the supremacy of the Constitution over international law in all respects; and, second, that in each major instance in which the Constitution incorporates international law as part of U.S. law, it retains the U.S. legislative, executive, and judicial power to determine--and revise--that content. The force of international law, for the United States, is a matter of U.S. law.

Part II, entitled "The Power To Say What International Law Is (for the United States)," addresses the interpretation of international law, for the United States, as an aspect of the Constitution's separation of powers. In this Section, I offer a detailed map of the U.S. constitutional power to interpret and apply international law.

Section II.A discusses Congress's power to interpret and apply international law in making U.S. law. The Congress, I submit, possesses exclusive constitutional power to determine the content of, and apply in the form of U.S. domestic criminal law, international law, as an aspect of its power "[t]o define and punish Piracies and Felonies committed on the high Seas, and Offences against the Law of Nations." (6) In addition, Congress possesses substantial constitutional power to pass laws it fairly judges "necessary and proper" for executing the treaty power of the United States and, further, to enact laws contravening or superseding the requirements of such treaties as a matter of U.S. domestic law (pursuant to one or another of its enumerated legislative powers). (7) These legislative powers to some extent "bound" the President's power to...