Let’s say you’ve just heard that the National Popular Vote Interstate Compact is a way to elect the presidential candidates with the most votes, without changing the Constitution. But you, dear reader, are an informed citizen who knows that Article I, Section 10, Clause 3 of the US Constitution, also known as the Compacts Clause, states:

“No State shall, without the Consent of Congress…enter into any Agreement or Compact with another State.”

Doesn’t the National Popular Vote Interstate Compact, an agreement between states with the word “compact” right there in the name, require the consent of Congress? The US Supreme Court jurisprudence says no.

Compacts only need congressional approval if they encroach on federal power

The US Supreme Court has repeatedly held that only interstate compacts that encroach upon federal powers require congressional approval. The Court admits that, if read literally, the Compacts Clause would require congressional approval for any interstate compact. However, it has rejected that literal reading. Instead, the Court consistently holds that congressional approval is only necessary where an interstate compact would “enhance state power to the detriment of federal supremacy” (US Steel Corporation v. Multistate Tax Commission 1976, 434 US 452, 459 – 460).

The 1893 case of Virginia v. Tennessee involved an agreement about where the border existed between two states, which had made between the states without approval of Congress. In this case, the US Supreme Court held that the states had the power to sign and enforce such a compact, without congressional approval. The Court also held that the Compacts Clause only applies to agreements “tending to the increase of political power in the States, which may encroach upon or interfere with the just supremacy of the United States.” The test of whether a compact requires congressional approval is whether it increases the power of the states and encroaches on “federal authority” (Virginia v. Tennessee 1893, 148 US 503, 519).

The Court reaffirmed this ruling in 1976 and again in 1978. In the 1976 case, it involved another interstate agreement about state boundaries and the Court concluded that “neither State can be viewed as enhancing its power in any sense that threatens the supremacy of the Federal Government” (New Hampshire v. Maine 1976, 426 US 363, 370). The 1978 case of US Steel Corporation v. Multistate Tax Commission addressed a multistate compact formulated by state tax administrators to stave off federal encroachment on the power of the states to tax multi-state businesses. The compact created a commission empowered to conduct audits of businesses operating in multiple states and gave multistate businesses a choice of formulas for calculating their state taxes.

The Multistate Tax Compact would come into force when any seven or more states enacted it. By 1967, the requisite number of states had approved the compact. These states submitted the compact to Congress for its consent and encountered fierce political opposition by various business interests concerned about the more stringent tax audits. Despite this opposition, the compacting states proceeded to implement the compact without congressional consent. US Steel and other companies challenged the states’ action.

The Court upheld the compact’s validity without congressional approval, where the Court admitted that banding together would give the states more influence than what each state had alone. However, the compact did not give states “any powers they could not exercise in its absence” (US Steel Corporation v. Multistate Tax Commission 1976, 434 U.S. 452, 473). The test, the Court said, was “whether the particular compact enhances state power [with respect to] the Federal Government” (Id. at 453).

Several other Supreme Court decisions upheld a variety of interstate agreements without congressional consent, e.g., St. Louis & S F. R. Co. v. James 1896, 161 US 545; Hendrick v. Maryland 1915, 235 US 610; Bode v. Barrett 1953, 344 US 583; New York v. O’Neill, 1959, 359 US 1. These cases didn’t explicitly apply the Virginia v. Tennessee test but they reaffirmed its underlying assumption: the Compact Clause is not to be read literally—not all agreements between states require congressional approval.

Selection of electors is a state power, not a federal one

The key legal test, established by more than a century of Supreme Court jurisprudence, is whether an interstate compact encroaches on federal supremacy. Or, as the Court said in the 1976 Multistate Tax Commission case, a compact should not give states any powers they could not exercise in its absence. Does the National Popular Vote Interstate Compact encroach on federal powers to enlarge state powers?

Not at all.

The Constitution is clear that states have the exclusive power to select electors. Article II, Section 1, Clause 2 of the U.S. Constitution states:

“Each State shall appoint, in such Manner as the Legislature thereof may direct, a Number of Electors.”

The US Supreme Court has ruled that, when it comes to deciding how to appoint electors, “the power and jurisdiction of the State is exclusive” [Emphasis added] (McPherson v. Blacker 1892, 146 US 1, 35).

Because the states have the exclusive power to choose the method of appointing their presidential electors, an interstate compact about how to choose electors does not encroach on federal power.

Tweet This

The Court’s conclusion that states have exclusive power is made clear by contrasting the Constitution’s language about presidential elections (Article II Section 1, above) with the language about congressional elections (Article II Section 4). There, states decide when and where to hold elections, “but the Congress may at any time by Law make or alter such regulations.” This makes clear that states do not have exclusive power of congressional elections, but they do have exclusive power to choose electors.

Because the states have the exclusive power to choose the method of appointing their presidential electors, an interstate compact about how to choose electors does not encroach on federal power.

The Compact changes state laws, not the Constitution

Tara Ross, an opponent of the National Popular Vote Interstate Compact, has argued that: “If the NPV compact goes into effect, its proponents will have effectively changed the presidential election procedure described in the Constitution, without the bother of obtaining a constitutional amendment.” Therefore, Ross implies that the compact encroaches on the constitutional amendment process, which encroaches on federal power.

However, “the presidential election procedure described in the Constitution” gives each state a number of electors and the exclusive power to choose how to appoint those electors. This compact wouldn’t change that. Signatory states would simply change their state laws from appointing electors loyal to the party that won the most votes in the state, to those loyal to the party that won the most votes in the country. States have exclusive authority to change their own electoral appointment rules and have done so many times in the past. Most states used some other method in the eighteenth century and switched to the state-winner-take-all method in the nineteenth century. It is within their power to switch to a national-winner-take-all method in the twenty-first century.

Nonetheless, congressional approval would be nice

The Supreme Court could change its mind, override its past decisions, and hold that the Compacts Clause should be read literally, and the National Popular Vote Interstate Compact would not go into effect until it received congressional approval. For this reason, advocates are seeking congressional approval for the compact. But if the Court follows its own precedent, the compact, once passed by the requisite number of states, would activate and elect the candidate with the most votes.


Sightline Institute is a 501(c)3 non-profit organization and does not support, endorse, or oppose any candidate or political party.

State winner-take-all Electoral College distorts the will of American voters. Learn more about the benefits for voters with a top-four primary, ranked choice voting and other proven democracy solutions in Sightline's New Book: Becoming a Democracy--a field guide to what's possible. How we can fix the Electoral College, Gerrymandering, and Our Elections.Kristin Eberhard, Director, Climate and Democracy and author of Becoming a Democracy: How We Can Fix the Electoral College, Gerrymandering, and Our Elections, is a researcher, writer, speaker, lawyer, and policy analyst who spearheads Sightline Institute’s work on democracy reform and on climate action. She researches, writes about, and speaks about elections systems and democracy reform, with particular expertise on Vote By Mail and proportional representation. Eberhard lives in Oregon, an all-Vote By Mail state. She is available to discuss tested, safe, fair COVID-19 election practices, state by state. Find all Eberhard’s latest research here.

Thanks to Nisha Balaram for editing. 

For press inquiries and interview requests, please contact Anna Fahey.


January 19, 2021