There is ongoing legal debate about the constitutionality of the National Popular Vote Interstate Compact in the United States. At issue are interpretations of the Compact Clause of Article I, Section X, and states' plenary power under the Presidential Electors Clause of Article II, Section I.
Compact Clause The Compact Clause of Article I, Section X of the United States Constitution states that "No State shall, without the Consent of Congress ... enter into any Agreement or Compact with another State". In a report released in October 2019, the Congressional Research Service (CRS) cited the U.S. Supreme Court's ruling in Virginia v. Tennessee (1893) as stating that the words "agreement" and "compact" are synonyms, and 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". However, 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 the compacting state governments is altered in favor of the compacting state governments—which the Court reaffirmed in New Hampshire v. Maine (1976), U.S. Steel Corp. v. Multistate Tax Commission (1978), Cuyler v. Adams (1981), and Northeast Bancorp v. Federal Reserve Board of Governors (1985).
The CRS report states that "Whether the NPV initiative requires congressional consent under the Compact Clause first requires a determination as to whether NPV even constitutes an interstate compact." Yale Law School professor Akhil Amar, one of the compact's framers, has argued that because the NPVIC does not create a "new interstate governmental apparatus" and because "cooperating states acting together would be exercising no more power than they are entitled to wield individually", the NPVIC probably does not constitute an interstate compact and cannot contravene the Compact Clause. Conversely, 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 but not a necessary condition for an agreement to qualify as being an interstate compact under the Compact Clause. Instead, the CRS report cites the Court's opinions in Virginia v. Tennessee and Northeast Bancorp 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. Noting that the NPVIC meets all of those requirements, the CRS report concludes that "the initiative can be described as an interstate compact."
Vertical balance of power shift
As part of concerns about whether the NPVIC would shift power from the federal government to state governments, at least two legal commentators have suggested that the NPVIC would require explicit congressional approval because it would remove the possibility of contingent elections for President being conducted by the U.S. House of Representatives under the 12th and 20th Amendments. The CRS report notes that the outcomes of only two presidential elections (1800 and 1824) have been decided by a contingent election, and whether the loss of such elections would be a de minimis diminishment of federal power is unresolved by the relevant case law. The report references 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 that the potential erosion of an enumerated power of the U.S. House of Representatives could arguably require explicit congressional approval. National Popular Vote Inc. has stated that if removing the possibility of contingent elections is grounds for unconstitutionality (rather than the requirement of explicit congressional approval), then Congress setting the size of the House at an odd number, as it did in 1911 (resulting in an odd number of electors until 1961), was also unconstitutional because it precluded the possibility of a tie in the Electoral College between presidential candidates.
However, under the 12th Amendment, contingent elections are not held only in the event of a tie but rather if no candidate receives "a majority of the whole number of Electors appointed", which can occur regardless of whether the size of the Electoral College is set at an even or odd number if more than two candidates receive electoral votes. In 1824, no electoral vote tie occurred, four candidates for President (Andrew Jackson, John Quincy Adams, William H. Crawford, and Henry Clay) received electoral votes, and all four candidates failed to reach the 131 votes necessary for a majority of the Electoral College, which was set at 261 electors. While there have been no contingent elections for President since 1824, more than two candidates have received non-faithless electoral votes in 10 presidential elections since (1832, 1836, 1856, 1860, 1892, 1912, 1924, 1948, 1960, and 1968). Since the compacting states under the NPVIC would be awarding their electoral votes to the presidential ticket that wins the national popular vote, contingent elections for Vice President being conducted by the U.S. Senate would also be precluded by the NPVIC. The only contingent election for Vice President was held following the 1836 presidential election.
Ratified in 1804, the 12th Amendment revised the procedure by which the Electoral College operates and contingent elections are conducted. The 12th Amendment required that contingent elections be held before March 4 and this effectively delegated their conduct to lame-duck sessions of the House and Senate, but this requirement would be superseded by Sections 1 and 2 of the 20th Amendment. Ratified in 1933, Section 1 of the 20th Amendment changed the expiration date for congressional terms of office to January 3 and presidential and vice presidential terms of office to January 20, and Section 2 of the 20th Amendment changed the commencement date of congressional sessions to January 3 from the first Monday of December under the Congressional Sessions Clause of Article I, Section IV. Consequently, incoming sessions of the House and Senate now conduct contingent elections rather than lame-duck sessions. However, under the 12th Amendment, state delegations to the House of Representatives still cast a single vote as a delegation in contingent elections for President, and the District of Columbia has no vote in contingent elections for President or Vice President.
In the contingent election that followed the 1800 presidential election (which was conducted under the Electoral College Clause of Article II, Section I), the House of Representatives did not elect Thomas Jefferson as President over Aaron Burr (who were both members of the Democratic-Republican Party) until the 36th ballot of the contingent election on February 17, 1801—only 15 days before the presidential term of John Adams expired on March 4—because the contingent election was conducted by the lame-duck session of the 6th United States Congress when the House of Representatives was controlled by the Federalist Party and because there was an even number of state delegations to the House of Representatives casting ballots. Section 3 of the 20th Amendment provides that if a President-elect is not chosen before Inauguration Day that the Vice President-elect acts as President until a President is chosen in the event that contingent elections conducted by Congress fail to elect a President or Vice President by Inauguration Day, while the Vice President-elect becomes the President if the President-elect dies before Inauguration Day.
Section 4 of the 20th Amendment grants Congress the power to pass legislation to specify what occurs in contingent elections if one of the candidates the House of Representatives or Senate chooses from dies. While a Vice President-elect that succeeds to the Presidency under Section 3 of the 20th Amendment due to the death of the President-elect has the authority to appoint a Vice President once in office under Section 2 of the 25th Amendment, if a Vice President-elect becomes Acting President under Section 3 of the 20th Amendment, the Vice President-elect could serve an entire four-year term as an Acting President and not succeed to the Presidency if the President-elect that fails to qualify does not die before Inauguration Day. National Popular Vote Inc. has argued that eliminating the possibility of contingent elections would be a collateral benefit of the NPVIC, and has noted that Congress has never viewed its power to conduct contingent elections as a factor when increasing the size of the House of Representatives.
Willamette University College of Law professor Norman R. Williams has argued that the 1787 Constitutional Convention delegates chose the Electoral College to choose the President largely in reaction to the experience during the Confederation period where state governors were often chosen by state legislatures and wanting the new federal government to have an executive branch that was effectively independent of the legislative branch. Citing political scientist Gary L. Gregg, National Popular Vote Inc. notes that the Constitutional Convention delegates did not expect the Electoral College to regularly fail to produce a candidate with a majority of electoral votes and routinely require the House of Representatives to choose the President in a contingent election. Also, members of Congress may object to the counting of electoral votes of any state or the District of Columbia at the Electoral College vote count under the Electoral Count Act (ECA) and the Electoral Count Reform Act (ECRA). Section 109 of the ECRA provides that the total number of electors appointed for determining a majority under the 12th Amendment is reduced by the number of electors for whom objections are sustained when electors have not been lawfully certified, while electors providing votes that have not been regularly given still count towards the total number of electors appointed and the votes are deducted from the electoral vote total of the candidate to whom they were cast.
Horizontal balance of power shifts
The CRS report goes on to cite 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 among the compacting states, and notes that the Court suggested in Multistate Tax Commission and Northeast Bancorp that the Compact Clause is also concerned with preserving the horizontal balance of power between compacting and non-compacting states to interstate compacts (even though the Court rejected the claims that the non-compacting states saw a loss of power in both cases). University of Colorado Law School professor Jennifer S. Hendricks and labor lawyer Bradley T. Turflinger have argued that the NPVIC would not alter the power of non-compacting state governments because all state governments would retain their right to select the electors of their choosing and their mode of appointment.