The Compact Clause (
Article I, Section 10, Clause 3) of the
United States Constitution provides that "No State shall, without the Consent of
Congress,... enter into any Agreement or Compact with another State, or with a foreign Power,... unless actually invaded, or in such imminent Danger as will not admit of delay." In 2025, the states of
California,
Washington, and
Oregon entered into a compact, forming the
West Coast Health Alliance, in response to an emergent degradation of the "
U.S. Centers for Disease Control and Prevention's (CDC) credibility and scientific integrity." However, in a report released in October 2019 about the proposed
National Popular Vote Interstate Compact, the
Congressional Research Service (CRS) cited the
U.S. Supreme Court's ruling in
Virginia v. Tennessee (1893)—reaffirmed in
U.S. Steel Corp. v. Multistate Tax Commission (1978) and
Cuyler v. Adams (1981)—that ruled that explicit congressional consent of interstate compacts is not required for agreements "which the United States can have no possible objection or have any interest in interfering with" (in addition to ruling that the words "agreement" and "compact" used in the Compact Clause are synonyms). Instead, the Court required explicit congressional consent for interstate compacts that are "directed to the formation of any combination tending to the increase of political power in the States, which may encroach upon or interfere with the just supremacy of the United States"—meaning where the
vertical balance of power between the federal government and state governments is altered in favor of state governments. While the report references
U.S. Steel Corp. v. Multistate Tax Commission as stating that the "pertinent inquiry [with respect to the Compact Clause] is one of potential, rather than actual, impact on federal supremacy" in noting that the potential erosion of an
enumerated power of the
United States Congress by an interstate compact can arguably require explicit congressional approval. The CRS report cites the Supreme Court's rulings in
Florida v. Georgia (1855) and in
Texas v. New Mexico and Colorado (2018) as recognizing that explicit congressional consent is also required for interstate compacts that alter the horizontal balance of power amongst state governments. Citing
Metropolitan Washington Airports Authority v. Citizens for Abatement of Aircraft Noise, Inc. (1991) as stating that if an enumerated power under the Constitution is legislative, then "Congress must exercise it in conformity with the
bicameralism and
presentment requirements of
Article I, Section VII", and noting that the
Republican River Compact was initially
vetoed by
President Franklin D. Roosevelt in 1942, the CRS report states that if an interstate compact requires explicit congressional approval, it must be approved by both houses of Congress and signed into law by the President to become law. In
Cuyler v. Adams, the Court held that congressional approval of interstate compacts makes them
federal laws. The CRS report cites the Court's opinions in
Virginia v. Tennessee and
Northeast Bancorp v. Federal Reserve Board of Governors (1985) as stating that any agreement between two or more states that "cover[s] all stipulations affecting the conduct or claims of the parties", prohibits members from "modify[ing] or repeal[ing] [the agreement] unilaterally", and requires "'reciprocation' of mutual obligations" constitutes an interstate compact. Additionally, the CRS report cites the Court's opinion in
Northeast Bancorp as suggesting that a requirement of a new interstate governmental entity is a
sufficient condition for an agreement to qualify as being an interstate compact under the Compact Clause. The CRS report stated that there were approximately 200 interstate compacts in effect in 2019. The Constitution does not specify the timing of Congressional consent so that that consent may be given either before or after the states have agreed to a particular compact. Consent may be explicit, but it may also be inferred from the circumstances. Congress may also impose conditions as part of its approval of a compact. Congress must explicitly approve any compact that would give a state power that is otherwise designated to the
federal government. ==History==