compacts

In American constitutional law, interstate compacts are contractual agreements entered into by two or more states to address matters of common concern, deriving their authority from the Interstate Compact Clause of Article I, Section 10, Clause 3 of the U.S. Constitution, which provides that "No State shall, without the Consent of Congress... enter into any Agreement or Compact with another State, or with a foreign Power." This clause traces its lineage to Article VI of the Articles of Confederation, and it establishes that compacts touching upon federal supremacy or the balance of power among states require congressional consent. The Supreme Court clarified in Virginia v. Tennessee (1893) that not every interstate agreement requires such consent—only those tending to increase the political power of states in a manner encroaching upon federal supremacy. Once consented to by Congress, a compact becomes federal law binding on the signatory states under the Supremacy Clause.

Compacts function as both statutes and contracts: they are enacted through parallel legislation in each member state and, where required, ratified by an act of Congress. This dual character means a state cannot unilaterally nullify or amend its obligations through subsequent domestic legislation, a principle affirmed in West Virginia ex rel. Dyer v. Sims (1951) and Cuyler v. Adams (1981), where the Court held that a congressionally consented compact is transformed into federal law subject to federal judicial interpretation. Compacts may create administrative commissions with quasi-governmental authority, such as the Port Authority of New York and New Jersey, established by compact in 1921. They cover diverse fields including water apportionment, taxation, corrections, education, and emergency management.

Prominent examples include the Colorado River Compact (1922), apportioning water among seven southwestern states; the Emergency Management Assistance Compact (EMAC, 1996), which coordinates interstate disaster response and was activated extensively after Hurricane Katrina in 2005; the Driver License Compact; and the Interstate Compact for Adult Offender Supervision (2002). The Multistate Tax Compact and the proposed National Popular Vote Interstate Compact—which would award member states' electoral votes to the national popular-vote winner and had garnered states totaling over 200 electoral votes by 2026—illustrate the instrument's continuing political vitality. The Council of State Governments' National Center for Interstate Compacts tracks more than 200 active compacts as of 2026.

For the FSOT (Foreign Service Officer Test) U.S. Government section, compacts test the candidate's grasp of federalism, the distribution of powers between states and the national government, and the constitutional mechanisms that permit horizontal cooperation among states. Examiners typically frame questions around the constitutional basis (Article I, Section 10), the requirement and rationale for congressional consent, and the distinction between compacts requiring consent and informal cooperative arrangements that do not. Candidates should connect compacts to the broader theme of cooperative versus dual federalism and be prepared to identify landmark compacts and their subject matter. Comparative questions may contrast compacts with treaties (reserved exclusively to the federal government under Article II) and with executive agreements, reinforcing the principle that states are barred from independent foreign relations.