The Insurrectionist State Legislature Theory (ISLT) Score illustrates the risk that the Supreme Court case, Moore v. Harper, poses to the integrity of the 2024 presidential election in each state. Our analysis seeks to measure the potential impact of a Supreme Court decision that adopts a maximalist version of what Republicans call the “Independent State Legislature Theory,” which would allow state legislatures to change procedures relating to federal elections in their states without checks and balances, such as gubernatorial vetoes, state constitutional provisions, state courts, independent redistricting commissions, and voter-initiated legislation. 

The violent January 6, 2021 insurrection by former President Donald Trump and his Republican allies, as well as voter suppression and election administration interference legislation championed by state legislators since the 2021 coup attempt, form the basis of our analysis. An adverse ruling in Moore v. Harper could allow Republican state legislatures to alter procedures for federal elections in their state to illegitimately alter the outcome of the 2024 presidential election. Here, we analyze how vulnerable each state — and its electoral votes — would be to intentional interference by Republican state legislatures under a maximalist version of ISLT.

All 50 states received an ISLT score, as did the swing district and electoral vote in both Nebraska and Maine (Nebraska 2nd and Maine 2nd districts). Seven variables factored into the ISLT scoring: 

1. Margin of victory: The margin of victory in the 2020 presidential election indicates the closeness of the last presidential race, measured by the difference between percent of votes received by the victor of the state and the percent of votes received by the  second-place candidate. The margin of victory in the state matters because states with the closest margins of victories are more likely to flip as a result of voter suppression bills and other tactics that could be unleashed by a rogue, unaccountable state legislature. 
2. Partisan control of state legislature: The partisan control of the state legislature indicates whether Democrats or Republicans hold majorities in both state legislative houses, or whether the two parties split control (ie; one party controls the upper house while the other controls the lower house). The partisan control of the state legislature is included because Republican operatives supported and carried out an insurrectionist coup to undermine democracy in the last election, and have demonstrated a desire to overturn democratic election outcomes if necessary in order to gain power.
3. Senate control proportion: This factor measures the percent of state senate seats controlled by Republicans. State senates with higher Republican majorities are more at-risk because more Republican legislators in those states would need to defect from their party to defeat insurrectionist legislation.¹
4. House control proportion: This factor measures the percent of state house seats controlled by Republicans. State houses with higher Republican majorities are more at-risk because more Republican legislators in those states would need to defect from their party to defeat insurrectionist legislation.
5. Republican skew of state senate: Republican skew of the state senate is calculated by subtracting the percent of votes won by Donald Trump in the 2020 presidential race from the percent of senate seats controlled by Republicans. A skew toward the GOP indicates that the state legislature, which could be empowered to enact radical federal election law changes under ISLT, is not representative of the will of the state’s voters and may well be insulated from being held accountable by those voters.²
6. Republican skew of state house: Republican skew of the state house is calculated by subtracting the percent of votes won by Donald Trump in the 2020 presidential race from the percent of house seats controlled by Republicans. A skew toward the GOP indicates that the state legislature, which could be empowered to enact radical federal election law changes under ISLT, is not representative of the will of the state’s voters and may well be insulated from being held accountable by those voters.
7. Bills: The number of bills introduced by state legislatures in 2021 and 2022 that Voting Rights Lab identified as suppressing votes or interfering with election administration. A higher number of introduced bills indicates more momentum in the state legislature to influence the 2024 election.

¹ The proportion of control in the Nebraska unicameral legislature was used for both its senate control proportion and house control proportion.
² The Republican skew score in the Nebraska unicameral legislature was used for both its senate Republican skew and house Republican skew.