Compact Clause

The compact clause of the United States Constitution prohibits states from entering into any agreement or compact with other states or foreign powers without the consent of Congress. The clause ensures that states do not create factions within the union, and that the federal government remains supreme in matters involving foreign affairs.

At the time of the founding, the independent colonies could have formed their own countries or individualized agreements with one another. Instead, they formed a confederation where all would unite together under a single governing document, the Articles of Confederation. In order for this arrangement to work, the colonies could not enter into side agreements with each other or with foreign powers. The Articles of Confederation prohibited colonies from entering such agreements without the consent of Congress. Later, states approved a similar prohibition in the compact clause of Article I, Section 10, of the Constitution.


As originally conceived, the compact clause would help protect the newly formed federal government. It would complement Congress's power over matters like the regulation of commerce and foreign affairs, ensuring that states would not proceed with similar regulation without congressional consent. It would also protect the new republic against the risk of competing regional factions that might destabilize the union. The requirement that Congress must approve of any compact assured that national interests would always be considered.

In an increasingly complex society, states have used interstate compacts with greater regularity. Compacts allow states to set land boundaries, coordinate transit systems, collect taxes from online sales, and manage waterways with one another to improve efficiency and standardize regulations. But obtaining consent from Congress for some of these compacts has proved difficult, sometimes because of political pressure or their perceived low importance.

Many compacts do not need the express approval of Congress. Over time, the US Supreme Court has interpreted the compact clause to require only a narrow class of compacts that require congressional consent: only those that affect the balance of political power with noncompacting states or the federal government must be approved by Congress. The Court reasoned that only those kinds of compacts require national consideration from Congress.

This pragmatic approach has left little role for the compact clause. For instance, in U.S. Steel Corp. v. Multistate Tax Commission, 434 U.S. 452 ( 1978 ), the Supreme Court approved a multistate tax commission's power to adopt advisory tax regulations to ease administrative burdens, even without congressional consent. It reasoned that this multistate compact did not increase the power of the states involved because states could do the same thing individually without a compact, and because states could leave the compact at any time.

The Court's narrow approach to the congressional consent requirement gives flexibility to states, but the outer bounds of the compact clause remain unclear. Consider a new proposal called the National Popular Vote. It seeks to change the method of electing the president of the United States. Compacting states would agree to give their electoral votes to the winner of the national popular vote, effectively turning presidential elections into nationwide popular elections, if enough states enter the compact. Whether states' coordination of electoral votes is a compact that requires congressional consent remains a subject of speculation and dispute.

SEE ALSO Article IV, United States Constitution ; Federalism in American History .


Engdahl, David. “Characterization of Interstate Arrangements: When Is a Compact Not a Compact?” Michigan Law Review 64, no. 1 (1965): 63–104.

Frankfurter, Felix, and James Landis. “The Compact Clause of the Constitution: A Study in Interstate Adjustments.” Yale Law Journal 34, no. 7 (1925): 685–758.

Greve, Michael S. “Compacts, Cartels, and Congressional Intent.” Missouri Law Review 68, no. 2 (2003): 285–387.

Muller, Derek T. “The Compact Clause and the National Popular Vote Interstate Compact.” Election Law Journal 6, no. 4 (2007): 372–93.

Derek T. Muller
Pepperdine University School of Law

(MLA 8th Edition)