The State Treaty Clause

No State shall enter into any Treaty, Alliance, or Confederation. . . .

—Julian G. Ku

Introduction

The Constitution explicitly delegates to the President the power to “make Treaties” with the advice and consent of the Senate.¹ (See Essay No. 106.) The Constitution also expressly prohibits state treaty-making. This explicit textual prohibition reminds us that the Framers established bright-line rules to prohibit certain state government activities that were deemed most dangerous to the nation as a whole.

On this point, at least, the Framers appear to have been largely successful. States are barred from entering into treaties and can enter into interstate “compacts” only with congressional consent. However, states have unilaterally entered into “agreements” with foreign nations that, at least in some regards, function like treaties.

History Before 1787

Under British rule, the colonies lacked the power to negotiate their own treaties. With the Declaration of Independence, the “Free and Independent States” asserted the “full Power to . . . conclude Peace” and “contract Alliances,”² and as independent states, these sovereigns could negotiate treaties.

However, the states would soon surrender their unilateral power to make foreign alliances. Under the Articles of Confederation, states could enter into “any conferrence, agreement, alliance, or treaty” with foreign powers or other states as long as Congress approved.³

The Constitutional Convention

The Framers would impose an absolute ban on state treaty-making. An early proposal from the Committee of Detail combined what would become the State Treaty Clause and the Compact Clause. It barred states from entering into treaties, alliances, or confederations with “any foreign power” but, if Congress consented, allowed them to enter into agreements or compacts with other states.⁴ These provisions were later made separate provisions.⁵

It is not clear how the Constitution distinguished between the terms “treaties, alliances, and confederations” as international agreements and domestic “agreements and compacts.” Eighteenth-century commentators of international law, who were read by the Framers, provide useful guidance on the original public meaning of these words. Vattel was the most influential international law authority among the Framers’ generation. He wrote that treaties were “made with a view to the public welfare by the superior power, either for perpetuity, or for a considerable time.”⁶ On the other hand, Vattel defined compacts as “temporary matters” that “are accomplished by one single act, and not by repeated acts.”⁷ Christian de Wolff, another influential commentator, explained that “if two nations reciprocally agree to furnish troops to each other in time of war, this stipulation is called a treaty; but if one nation permits another, on account of the high price of grain, to purchase in its territory, this will be a compact.”⁸

The Ratification Debates

In Federalist No. 44, James Madison wrote that the proposed State Treaty Clause was already “part of the existing articles of union; and for reasons which needed no explanation, is copied into the new constitution.” This is a curious statement because, as noted above, the Constitution imposes a complete ban on “treaties, alliances, and confederations,” whereas the Articles allowed states to engage in such activities with congressional consent. Madison may have thought the change unimportant. The State Treaty Clause was not controversial in the state ratification conventions.

Judicial Precedent

During the early years of the Republic, the meaning or impact of the State Treaty Clause sparked no litigation and very little commentary. An early discussion of the clause came in Holmes v. Jennison (1840).⁹ Chief Justice Roger B. Taney’s plurality opinion noted that states were “positively and unconditionally” forbidden from entering treaties, even with congressional approval. Taney also recognized, however, that Congress could consent to state “compacts.” But nothing in that case turned on the distinction between these terms. The Supreme Court’s most detailed discussion of the issue simply concluded that “[t]he records of the Constitutional Convention . . . are barren of any clue as to the precise contours of the agreements and compacts governed by the Compact Clause.”¹⁰ The Court suggested that the original understanding of the terms has been historically “lost.”

The Supreme Court has decided other cases involving the State Treaty Clause. In Barron v. City of Baltimore (1833), Chief Justice John Marshall pointed to the State Treaty Clause as evidence that the Constitution does not “apply to the state government, unless expressly stated in its terms.”¹¹ Williams v. Bruffy (1878) held that the Confederate States of America could not “be regarded . . . as having any legal existence” because the Constitution “prohibits any treaty, alliance, or confederation by one State with another.”¹²

In 2017, California entered into a cap-and-trade agreement with Quebec and Ontario to reduce greenhouse gas emissions.¹³ In 2019, the United States sued California, arguing that the agreement was in fact a treaty, which violated the State Treaty Clause.¹⁴ In March 2020, a federal district court ruled that “[n]ot all international agreements may be ‘treaties’ in the constitutional sense.”¹⁵ The court concluded “that the Agreement does not represent a ‘treaty’ within Article I of the Constitution.”¹⁶ While the case was on appeal, there was a change in administrations and the appeal was voluntarily dismissed.¹⁷

Open Questions

• States may not enter into “treaties,” but may enter into interstate “compacts” with the consent of Congress, and have unilaterally entered into “agreements” with foreign nations.¹⁸ How do these three terms differ from one another?¹⁹
• Is California’s cap-and-trade agreement an unconstitutional “treaty”?

1. Art. II, § 2. ↩︎
2. Declaration of Independence, ¶32. ↩︎
3. Articles of Confederation, art. VI, § 1. ↩︎
4. 2 Farrand’s 169. ↩︎
5. Id. at 577, 619. ↩︎
6. E. de Vattel, The Law of Nations; or, Principles of the Law of Nature Applied to the Conduct and Affairs of Nations and Sovereigns, bk. II, § 152 (Joseph Chitty ed. & trans., 1863) (1758). ↩︎
7. Id. ↩︎
8. Christian de Wolff, Jus Gentium Methodo Scientifica Pertactatum (J.B. Scott ed., 1983) (1749). ↩︎
9. 39 U.S. (14 Pet.) 540 (1840). ↩︎
10. U.S. Steel Corp. v. Multistate Tax Commission, 434 U.S. 452, 461–63 (1978). ↩︎
11. 32 U.S. 243, 248 (1833). ↩︎
12. 96 U.S. 176, 177 (1877). ↩︎
13. United States v. California, 444 F. Supp. 3d 1181, 1188 (E.D. Cal. 2020). ↩︎
14. Id. at 1189–90. ↩︎
15. Id. at 1192 (quoting United States v. Curtiss-Wright Export Corp., 299 U.S. 304, 318 (1936)). ↩︎
16. Id. at 1193. ↩︎
17. United States v. California, No. 20-16789, 2021 WL 4240403, at *1 (9th Cir. Apr. 22, 2021). ↩︎
18. Duncan B. Hollis, Unpacking the Compact Clause, 88 Tex. L. Rev. 741, 760 (2010). ↩︎
19. Abraham C. Weinfeld, What Did the Framers of the Federal Constitution Mean by “Agreements or Compacts”?, 3 U. Chi. L. Rev. 453 (1936). ↩︎