How does the Constitution limit the subject matter of the U.S.'s treaties? For decades, conventional wisdom adopted a textual emphasis--prohibitions and other limits on federal authority listed in the Constitution itself (e.g., the Bill of Rights) apply to U.S. treaties. (1) In contrast, proposals for subject matter limitations implied by federalism fared less well. The case of Missouri v. Holland is famous precisely because it dismissed the idea of any structural "invisible radiation" from the Tenth Amendment prohibiting treaties on subjects falling within the states' reserved powers. (2) The Supreme Court emphasized that U.S. treatymakers could not only conclude treaties independent of states' rights concerns, but that the Necessary and Proper Clause authorized Congress to implement them independent of its enumerated powers. (3) A more affirmative requirement that U.S. treaties regulate only subjects of "international concern" suffered a similar fate. (4) As the Restatement (Third) of the Foreign Relations Law of the United States notes, "Contrary to what was once suggested, the Constitution does not require that an international agreement deal only with 'matters of international concern.'" (5) Taken together, such pronouncements suggest federalism imposes neither affirmative nor negative limits on which treaties the United States concludes or how it implements them.
In recent years, Missouri v. Holland and its two holdings have come under increasing scrutiny. (6) Academics like Curtis Bradley called for limits on the treaty power itself, subjecting treaties to "the same federalism limitations that apply to Congress's legislative powers." (7) Others like Nicholas Rosenkranz looked to undermine Missouri v. Holland's suggestion that Congress could implement treaties beyond its enumerated powers under the Necessary and Proper Clause. (8) Both positions generated robust rebuttals from those committed to preserving Missouri v. Holland's canonical status in U.S. foreign relations law. (9)
These debates did little, however, to resuscitate the idea of affirmative federalism limits on the treaty power to matters of international concern. Critics dismissed such a test as incapable of protecting federalism in the mod- ern treaty context since "[t]oday, almost any issue can plausibly be labeled 'international.'" (10) Thus, when the Supreme Court agreed to consider the Chemical Weapons Convention Implementation Act (CWCIA) in Bond v. United States, court watchers focused almost exclusively on whether the Court would sustain Missouri v. Holland or reconsider its holdings. (11) Noticeably absent from the prognostications was any substantial discussion of defining the treaty power in "international" terms.
Bond was thus a surprising decision on two levels. First, the majority avoided the Missouri v. Holland issues entirely. (12) Second, the case demonstrated that the "international concern" test is neither dead nor dying. Those Justices offering views on the constitutional scope of the treaty power--Alito, Scalia, and Thomas--all accepted some version of that test. Justice Thomas authored a concurrence (joined by Scalia and (largely) Alito) devoted to demonstrating that "the Treaty Power can be used to arrange intercourse with other nations, but not to regulate purely domestic affairs." (13) In a separate concurrence, Justice Alito explained "that the treaty power is limited to agreements that address matters of legitimate international concern." (14)
This Article explores whether the Constitution limits the making and implementation of U.S. treaties to subjects of "international" intercourse or concern. It does so in two steps. First, I undertake the existential inquiry, asking if the Constitution requires a nexus between treaties and "international" subject matters. I argue that Justices Alito, Scalia, and Thomas are correct--and the Restatement (Third) is wrong--on the question of whether the Constitution imposes an affirmative subject matter limitation on the treaty power. Various modalities of constitutional interpretation--original meaning, historical practice, doctrine, structure, and prudence--offer evidence in support of some version of an "international concern" test. And this claim holds whether one endorses or rejects the claim that federalism requires reserved powers' limitations on the treaty power or treaty-implementing legislation. (15)
Assuming the existence of an international concern test, my second step analyzes its contours. Here, I part ways with Justices Alito, Scalia, and Thomas on what it means to require that treaties address matters of international intercourse or concern. For these Justices--and some other advocates--the line between international and domestic matters is static and objective, with a fixed line dividing "international" matters from "purely domestic" ones.
In contrast, I envision the treaty power's boundaries in subjective, rather than objective, terms. More specifically, I believe the international concern test is intersubjective, it operates by the presence or absence of a shared understanding among the relevant actors in the treaty process. Shared beliefs as to whether a particular subject matter is international undergird the processes for (i) making, (ii) ratifying, (iii) implementing, and (iv) applying treaties. To begin with, treatymaking itself operates as a referendum on the international nature of the subject matter under discussion. Where participants negotiate a treaty, it necessarily implies a shared belief that its subject matter deserves international regulation. If the participants lack such a shared belief, no treaty gets made. (16) Second, the U.S.'s ratification process incorporates an intersubjective test on the appropriateness of the subject matter as a U.S. treaty--only if the President and the Senate jointly accept the appropriateness of using the treaty vehicle to regulate the particular subject(s) in question, can ratification occur. The possibility of reservations and understandings offers both sides tools to adjust the treaty's subjects to redress any concerns about its reach. And where treaties require implementation or application, the beliefs of additional actors (e.g., Congress, the Court) come into play, as each has a role in deciding whether the treaty's implementation generally (or its meaning in a specific instance) coincides with the international concerns that the original treaty suggests.
The test is thus a staged one. In order to pass it, an intersubjective belief that the subject matter is international must exist at each level in the process. A treaty cannot be ratified unless negotiating States conclude it, and it cannot be implemented, absent ratification. The need to have this confluence of intersubjective understandings effectively limits the subject matter of U.S. treaties even in the absence of objective criteria. Simply put, U.S. treaties will only be formed (or ratified, implemented, or applied) where all relevant actors share a belief that the subject matter is sufficiently international in character.
Given the test's staged nature, the context for its application matters. As Bond itself illustrates, having an intersubjective understanding that a treaty addresses matters of international concern does not necessarily translate into finding that every claimed implementation or application of that treaty qualifies as such. None of the Justices in Bond objected to the Chemical Weapons Convention as lacking in international character. Yet they all viewed either Ms. Bond's prosecution or the application of the treaty's implementing legislation as not matters of international concern. (17)
Moreover, contra Justice Thomas, the international concern test is clearly dynamic. What is (or is not) a matter of international concern may shift as the beliefs of those involved in the treaty process shift. No issue is "purely" domestic (or international) for all times. At one time, the test may preclude treatymaking on a particular topic (e.g., human rights) because nation States (or the President and the Senate) cannot agree to do so, only to have the same actors shift their views at a later date and conclude treaties on that very subject. Alternatively, actors may decide that a particular topic (e.g., relations with Native Americans) no longer warrants treaty treatment even if they believed it did at some point in the past.
Part I of this Article elaborates the case for an international concern test under standard modalities of constitutional interpretation. Part II examines the contents of this test, noting the difficulties of existing objective approaches and introducing the concept of intersubjectivity as it relates to treaties. Part III elaborates an intersubjective international concern test by explaining its staged, contextual, and dynamic character, using examples drawn from U.S. treaty practice. I conclude by highlighting the importance of intersubjectivity to resolving one of the longest running puzzles of U.S. foreign relations law and calling for more research on whether, when, and how well constitutional actors generate shared understanding on the permissible boundaries of the treaty power.
THE CONSTITUTION REQUIRES THAT TREATIES ADDRESS MATTERS OF INTERNATIONAL CONCERN
In 1929, Charles Evans Hughes addressed the American Society of International Law on the question of constitutional limits inherent in the nature of the treatymaking power. The former Secretary of State and future Chief Justice of the Supreme Court offered a famous (and succinct) articulation of the international concern test:
The normal scope of the power can be found in the appropriate object of the power. The power is to deal with foreign nations with regard to matters of international concern. It is not a power intended to be exercised, it may be assumed, with respect to matters that have no relation to international concerns. (18)...