In its decision rejecting the legislature’s new congressional map, the Utah trial court included a lengthy discussion of quantitative measures of partisan fairness in districting. The legislature argued that partisan asymmetry and the mean-median difference should be used to assess its new map. The court responded, correctly in my view, that these are exactly the wrong metrics to use in Utah. These metrics are inapplicable in uncompetitive states like Utah, while other approaches, like the efficiency gap and ensemble analysis, do work in Utah’s political environment. The court’s decision is here.

The Court finds that the partisan bias test is unsuitable for assessing whether a redistricting plan in Utah purposefully or unduly favors or disfavors a political party. It is not among the best available measures to assess partisan favoritism in Utah.

First, because partisan bias assesses favoritism based solely on seat shares under a hypothetical 50-50 statewide election, scholars warn that it should not be applied in states like Utah where statewide elections are uncompetitive and a tied statewide election cannot plausibly be expected. The authors of the metric, Professors Andrew Gelman and Gary King, limited its application to “competitive electoral systems,” which they defined as states in which each party had won a majority of seats or votes in at least one election during the preceding two decades. Professor Gary King has since emphasized that partisan bias “is only appropriate for competitive situations where there is a potential for change in partisan outcomes (majority control, in particular).”

The Court finds that Utah’s statewide elections are highly uncompetitive. Democrats have not received a majority of the statewide vote in congressional elections in 35 years and have not won a majority of congressional seats since at least 1970. Republicans have also won every statewide election for president, governor, and other offices included in S.B. 1011’s partisan index during the last 25 years, nearly always with 20-plus margins. Utah’s highly uncompetitive environment also undermines the validity of the partisan bias test’s uniform shift assumption—that is, the assumption that the shift to a 50-50 statewide vote share would occur uniformly across districts. Since this scenario has not even remotely occurred in decades, it is at best unclear how electoral coalitions would shift to produce a 50-50 statewide election and whether the uniform shift assumption underlying the partisan bias test is satisfied in Utah. Thus, Utah does not satisfy the electoral conditions necessary for valid application of the partisan bias test.

Second, when applied in Utah to congressional plans, the partisan bias test yields paradoxical results that advantage Republicans and disadvantage Democrats. The test treats most 3-1 maps that include one Democratic-leaning district as biased in favor of Republicans and against Democrats, because in a hypothetical tied statewide election Democrats would not win two seats. At the same time, it treats 4-0 maps that guarantee Republicans all four seats as neutral. This irrational result stems from the test’s conflict with Utah’s political geography. To pass, a map must disperse Democrats across two districts to ensure they would win two seats in the hypothetical world of a tied statewide election. But because Democrats are a small, geographically concentrated minority, doing so dilutes their only opportunity in the real world to win one seat. . . .

Scholars have recognized this effect as the “Utah paradox”—one that is known to be gameable and the reason why partisan actors in Utah would opt to use partisan bias as their metric to assess congressional plans. Notably, the Legislature applied the partisan bias test only to congressional plans. Utah Code § 20A-19-103(1)(c), (g). The Legislature did not apply the partisan bias test to its own legislative maps or the state school board maps, all of which would fail the test for exhibiting pro-Republican bias. . . .

Unlike the partisan bias and mean-median difference tests—which yield wholly incoherent results in uncompetitive states—the efficiency gap is not inapplicable in a state as uncompetitive as Utah. As Dr. Warshaw explains, the original authors of the efficiency gap acknowledged that the efficiency gap may be inapplicable in states where one party consistently wins more than 75% of the vote, “[b]ut Utah does not fall into that category. So . . . Utah is not outside of the boundary conditions of the efficiency gap.”

The Court finds that, despite its drawbacks, the efficiency gap is an appropriate symmetry measure to consider in assessing congressional maps in Utah. It correctly identifies the party favored under a proposed congressional map and permits analysis of the extent to which that party is favored via comparison with historical congressional plans in other states. The efficiency gap is thus among the best symmetry measures available to evaluate partisan favoritism in Utah congressional maps and should be considered alongside other appropriate measures.

I’ve been too busy to blog much this past week, either about my own work or the NYU Democracy Project. But here are three essays from last week in the NYU Democracy Project series of 100 essays in 100 days on challenges to democracy today.

From Seth Masket, The Rise of Populism, Left to Right:

“The rise of populism has been a noted phenomenon in many democracies around the world in recent decades. But its development in the United States has not been even across party lines, with populism substantially transforming the modern Republican Party but only making a dent on the Democratic side. Yet this imbalance may be changing…

One could see the beginnings of this in Sen. Bernie Sanders’ (I-VT) 2016 run for the Democratic presidential nomination, as well as during the 2018 midterm elections, in which several progressive Democratic House challengers – with the backing of Sanders, Justice Democrats, and other related groups – threatened the party’s leadership. Yet, other than Alexandria Ocasio-Cortez (NY) and a few others, populist challenges largely failed on the Democratic side that year.

Yet, we could be seeing a stronger push within the Democratic Party heading into the 2026 midterms. Just as Republican elites had lost favor among their rank-and-file in 2016, so Democratic elites have lost favor among their rank-and-file in 2025. Democratic Party favorability among Democrats has been dropping steadily in 2025, while Republican Party approval among Republicans is rising. It’s only one election in one city, but Zohran Mamdani’s victory in New York City’s Democratic mayoral primary suggests a party ripe for a populist moment, with elites uncomfortable with his stances not only unable to prevent his nomination but ultimately closing ranks behind him as the nominee.

What would a left-populist takeover of the Democratic Party look like?…”

From Charles Stewart, Polarization Today: Lessons from the Gilded Age?:

Two related topics currently dominate public discourse among educated elites in the United States:  democratic backsliding and political polarization.  Although there are exceptions, this discourse tends to take the post-Watergate consensus about the rules of the political game as the benchmark for American democratic practice, bemoaning the accelerating decline in popular political civility and elite forbearance.

As important as the topic of democratic decline over the past generation is, it’s natural to ask about how the current situation fits into the larger arc of American political history.  When we answer this question, we see patterns repeating, or at least history rhyming.  This doesn’t necessarily counsel despair, but it does suggest that our current troubles aren’t entirely the doing of contemporary actors and circumstances.  And, it suggests that the path out of the current polarization and constitutional hardball will come from the inherent instability of the political coalitions that constitute the parties.

America has experienced similar eras of intense polarization to the present one.  The obvious reference point is the Civil War, both before and after the war.  The Second Party System—generally dated from 1828 to 1854—was designed in part to take slavery off the table and organize national politics along other lines, such as patronage.  The key was the maintenance of cross-sectional national political parties that contained conflict over slavery.  Social and population forces, along with the success of the regional Republican Party, eventually blew the lid off the Jacksonian system, leading to war.

The Civil War may have settled the constitutional issue of federal supremacy over the states, but it didn’t extinguish partisan polarization.  Indeed, the Republican Party, which supplanted the Whigs as the chief rival to the Democrats, was much more cohesive on national issues than the Whigs ever were.  Thus, during the Third Party System that followed, political interests became increasingly aligned with party identities in both the electorate and the government.  When we use DW-NOMINATE scores to chart political polarization (recognizing DW-NOMINATE’s limitations in charting such things), it is only in recent years that the level of party polarization has matched that of the Reconstruction and Gilded Age years…

From Michael Kang, Electoral Due Process:

In a free and fair democracy, the rules of the election need to be set before the election, but a few partisan state legislatures have begun trying to effectively change the election results after the fact when their candidates lose—shrinking the powers of newly elected officeholders and sometimes even unseating them altogether. 

Consider events in North Carolina and Wisconsin. Under Republican governors, Republican legislatures there expanded gubernatorial powers while their party held the office. When Democrats won the governor’s races in those states, though, the same legislatures convened rushed lame-duck sessions to strip away executive authority before the newly elected Democrats could take office. In Wisconsin, the legislature waited to see the result of the governor’s election and when a Democrat won, it hurriedly transferred key executive powers to the legislature, restricted the governor’s ability to handle lawsuits, and eliminated the newly created position of solicitor general.  In North Carolina, after a Democrat won the governor’s election, lawmakers abruptly cut his control over key state institutions, including the board of elections, required legislative approval over his cabinet appointments, and slashed his administration from 1,500 employees down to 425—exactly reversing the increase they enacted with a Republican in power.  And more recently last year, after a Democrat was elected again as governor, the legislature called another lame duck session to once more cut back the governor’s powers by making last-second use of a veto-proof supermajority they had just lost in the elections.  In other words, partisan legislative majorities have retroactively stripped power from elected offices when their political opponents win, in lame duck sessions before the newly elected officeholders can even oppose them legislatively.  Other state legislatures have abused their censure, expulsion, and impeachment discretion to strip away powers from, or outright remove, elected officeholders from the opposing party under circumstances that are basically unprecedented in their states’ history.  The worry is that these incidents will become commonplace in our hyperpartisan and politically hypercompetitive country…