Partisan Gerrymandering Research Articles

Partisan gerrymandering with geographically compact districts

Abstract Bizarrely shaped voting districts are frequently lambasted as likely instances of gerrymandering. In order to systematically identify such instances, researchers have devised several tests for so-called geographic compactness (i.e. shape niceness). We demonstrate that under certain conditions, a party can gerrymander a competitive state into geographically compact districts to win an average of over 70% of the districts. Our results suggest that geometric features alone may fail to adequately combat partisan gerrymandering.

Using Outlier Analysis to Detect Partisan Gerrymanders: A Survey of Current Approaches and Future Directions

Abstract The prospect of convincing courts to intervene in partisan gerrymandering has inspired a great deal of research and, recently, public attention. But how can neutral parties such as courts ...

An Antidote for Gobbledygook: Organizing the Judge's Partisan Gerrymandering Toolkit into Tests of Opportunity and Outcome

Abstract Despite recent setbacks, litigation-based challenges to extreme partisan gerrymandering continue, and quantitative methods for detection are more important than ever. Many measurement tool...

Making a Case for Two Paths Forward in Light of Gill v. Whitford

Abstract In light of the Supreme Court's ruling in Gill v. Whitford (2018), we propose two paths forward for establishing manageable standards to identify partisan gerrymanders. One is aimed most p...

Can State Courts Cure Partisan Gerrymandering: Lessons from League of Women Voters v. Commonwealth of Pennsylvania (2018)

Abstract In League of Women Voters et al. v. Commonwealth of Pennsylvania et al. (2018), henceforth abbreviated LWV, the Pennsylvania Supreme Court struck down that state's congressional plan as an...

Efficiency Gap, Voter Turnout, and the Efficiency Principle

Abstract Recently, scholars from law and political science have introduced metrics which use only election outcomes (and not district geometry) to assess the presence of partisan gerrymandering. Th...

An Impossibility Theorem for Gerrymandering

In 2018, the U.S. Supreme Court considered a proposed mathematical formula to help detect unconstitutional partisan gerrymandering. We show that in some cases, this formula only flags bizarrely-shaped districts as potentially constitutional.

Calculated democracy—Explorations in gerrymandering

SummaryThis paper describes a lesson centered around a metric for measuring partisan gerrymandering: the efficiency gap. We situate the efficiency gap in the current US political climate, describe the activity itself, and then provide recommendations for readers interested in adapting the lesson for their own classrooms.

Tools for Identifying Partisan Gerrymandering (PA)

In League of Women Voters v. Commonwealth of Pennsylvania (2018) the Pennsylvania Supreme Court struck down as a “severe and durable” partisan gerrymander the congressional map drawn by Republicans in 2011 and used in elections from 2012-2016. It did so entirely on state law grounds after a three-judge federal court had rejected issuing a preliminary injunction against the plan. After Pennsylvania failed to enact a lawful remedy plan of its own (due to a total disagreement as to how to proceed between the newly elected Democratic governor and the still Republican-controlled legislature), the Court then ordered into place for the 2018 election a map of its own drawn for it by a court-appointed consultant. In a split court, the Court map was endorsed only by judges with Democratic affiliations. Here we compare the 2011 and 2018 congressional maps in terms of a variety of proposed metrics for detecting partisan gerrymandering. We also examine the remedy map proposed by a group of Republican legislators and that proposed by the Democratic governor. We conclude that the 2011 map was a blatant and undisguised pro-Republican gerrymander. Moreover, the remedy map proposed by Republican legislators was a covert pro-Republican gerrymander (what we refer to as a “stealth gerrymander”). The Democratic governor’s proposed plan cannot be classified as a pro-Democratic gerrymander and indeed has if anything, a slight pro-Republican tilt. The 2018 court-drawn remedial map, by all measures, was not a gerrymander.

Drawing the Lines: Constraints on Partisan Gerrymandering in U.S. Politics

Drawing the Lines: Constraints on Partisan Gerrymandering in U.S. Politics

Improving the Efficiency Gap

Partisan gerrymandering and how to measure it have been the subject of several recent court cases and a lot of media coverage. The efficiency gap in particular has garnered a lot of attention. The creators of the efficiency gap, Nicholas Stephanopoulos and Eric McGhee, claim that the measure is a “tally of all the cracking [spreading voters of a party across many districts to diminish their influence] and packing [stuffing voters of a party into few districts to concentrate their influence] decisions in a district plan” (“Partisan gerrymandering and the efficiency gap.” U. Chi. L. Rev. 82, no. 2 [Spring 2015]: 831–900).

Math tools send legislators back to the drawing board

*UPDATE: On June 18, 2018, after this article went to press, the Supreme Court of the United States ruled on two high-profile cases related to partisan gerrymandering. In effect, the rulings sidestepped the issue of when partisan gerrymandering is unconstitutional. Both cases—one concerning voting districts in Wisconsin, the other in Maryland—were sent back to lower courts. On June 25, the SCOTUS ruled on two other cases—in Texas and North Carolina—that will mostly let stand the use of purportedly gerrymandered maps. On January 9, 2018, a trio of federal judges made history when they ruled that the boundaries of North Carolina’s congressional voting districts gave an unfair advantage to Republican candidates. It was the first case in the nation in which a federal court had declared congressional maps unconstitutional because of intentional bias in favor of one party. The case was all the more remarkable because the court decision relied in part on mathematical tools that can probe the practice of gerrymandering—the drawing of voting districts to give an intentional advantage to one party. Changing the boundaries of voting districts can have a significant impact on an election outcome. North Carolina’s 2012 election districting map (bottom) led to Republicans winning nine seats and Democrats winning four. North Carolina’s redistricting for the 2016 election (middle map) led to Republicans winning 10 seats and Democrats winning three seats. But an arguably fairer redistricting plan (top), produced by retired judges, would have led to Republicans winning seven seats and Democrats the other six in 2012; it would have been nine seats for Republicans and four for Democrats in 2016. Image courtesy of Jonathan Mattingly (Duke University, Durham, NC). It would be one of many gerrymandering cases. In February, the US Supreme Court rejected a request by Republican lawmakers to stay a lower court's decision—which …

Partisan gerrymandering and the illusion of unfairness

Partisan gerrymandering is frequently condemned for distorting democracy and causing unfair representation, and many reformers have called upon federal courts to prohibit the practice. However, the judiciary has struggled to advance a coherent approach to partisan gerrymandering. Conservative justices have argued the practice raises a non-justiciable political question, and the remainder of the bench has failed to reach any agreement on the right test. This Article argues that courts have struggled with the law because the threat from partisan gerrymandering is illusory. Parties are responsive to external conditions, including the composition of legislative districts. Therefore, voters, candidates, and party leaders can adapt to compete for the constituencies of redrawn districts. When partisan gerrymandering appears harmful, the true culprit is the fracturing of the electorate into factions due to voters’ political preferences. The appropriate forum for resolving such substantive disputes among citizens is democratic contestation, not rights-based judicial intervention. Subsequently, reformers’ hope that eliminating partisan gerrymandering will fix American democracy is misplaced. This divergence between the real character of partisan gerrymandering and its treatment by the legal academy is responsible for the lack of clarity in the jurisprudence. To support this conclusion, this Article draws on social science analysis of political behavior to offer a unified perspective on party affiliation, voter preference, and constitutional rights.

Crafting a Judicially Manageable Standard for Partisan Gerrymandering: Five Necessary Elements

Abstract Beginning with a definition of gerrymandering, and after a brief review of the evolution of the case law on partisan gerrymandering, I propose five necessary elements of a test for when pa...

Can State Courts Cure Partisan Gerrymandering: Lessons from <i>League of Women Voters v. Commonwealth of Pennsylvania</i> (2018)

In League of Women Voters et al. v. Commonwealth of Pennsylvania et al. (2018), the Pennsylvania Supreme Court struck down that state’s congressional plan as an unconstitutional partisan gerrymander. It did so entirely on state law grounds after a three-judge federal court had rejected issuing a preliminary injunction against the plan. The aim of this essay is to examine the implications of LWV for future partisan gerrymandering litigation. In particular, we look toward the applicability of the Pennsylvania court’s approach to other potential partisan gerrymandering challenges brought under state law, especially those in the twelve states whose state constitutions have provisions essentially identical to the one relied upon by the Pennsylvania Supreme Court, and in states with similar provisions. We pay particular attention to how the Court made use of the expert witness testimony in the case, relying on some of it, while rejecting or critiquing the applicability of other elements, since such a discussion can inform future litigation in state courts drawing on the LWV opinion for ideas. In our concluding discussion we contrast the criteria used to evaluate partisan gerrymandering by this court with those used by federal courts, and we look at how it may impact the decisions of legislators about line drawing in 2020.

An Antidote for Gobbledygook: Organizing the Judge's Partisan Gerrymandering Toolkit into a Two-Part Framework

The Supreme Court appears ready to limit partisan gerrymanders. However, defining extreme is a challenging proposition, since individual states differ in their political geography and legal circumstances. Many measurement tools have emerged that probe the questions of whether a redistricting map is extreme, or violates the principle of partisan symmetry. Here we provide a framework for categorizing these tests. Our framework explains how measures should be interpreted and identifies which tests will be most effective, given the specific facts of a particular state. Broadly, the tests can be divided into two categories: those that identify inequality of opportunity, i.e. a systematic deprivation of one side's ability to elect representatives; and those that identify inequality of outcome, i.e. a durable distortion in the amount of representation. In each case, the baseline for comparison is what would occur under districting processes in which partisan interests are not the overriding consideration. A general thread is that of significance testing, in which a district or statewide districting scheme can be defined as more than the great majority of possibilities that could arise incidentally through a districting process driven by criteria other than partisanship. Such tests are most often done with well-established classical statistical tests, but can also include recently-developed measures such as the efficiency gap. Many of these measures can be evaluated by a judge or clerk, with minimal need for reliance on expert witnesses. It is even now possible to evaluate, with mathematical rigor, whether a specific scheme is relative to the virtually uncountable universe of possible maps. Taken together, these methods for detecting extremes comprise a statistical toolbox to address a wide variety of circumstances that may arise in the post-Whitford, post-Benisek environment.

Using Wasted Votes to Evaluate Legislative Redistricting Plans: The Inefficiency Gap

Courts in the United States have expressed a need for a manageable standard for evaluating redistricting plans speaking to concepts of equal protection and one-person/one-vote. This paper builds upon the concept of “wasted votes” proposed by Stephanopolous and McGhee (2015). What share of wasted votes cast due to gerrymandering, dilutes a group’s voting power sufficiently to shift legislative seats from that group to the group whose members predominantly drew the redistricting plan? Courts can conditionally reject a redistricting plan based on the existence of an alternative plan more responsive to voter preferences and having sufficiently equal population and manageability based on geographic and political boundaries. Although cited recently by expert witnesses and justices, the “efficiency gap (EG)” and the “mean-median” gap, as previously constituted, are inconsistent measures upon which to base a decision to accept or reject redistricting plans. Three corrections to the EG measure results in a reliable inefficiency gap (IG) measure. Using the IG measure, a threshold may be chosen to indicate when redistricting plans shift one or more seats between voter groups due to diluting group members’ voting power via partisan gerrymandering. However, one correction to the EG measure proposed herein – weighting the wasted vote shares by each voter groups’ lost seat share – improves the EG’s reliability in most likely scenarios. This paper tests several standards against hypothetical reapportionment plans having varying amounts of vote shares, legislative seats, and “stacking” and “cracking” or no gerrymander bias. The results show the proposed “inefficiency gap (IG)” measure, by adopting three mathematical improvements to the EG measure, reliably meets the legal needs of state and federal courts for a manageable standard.

Constitutional Preservation and the Judicial Review of Partisan Gerrymanders

This essay makes three contributions to the debate over whether the Constitution contains a judicially enforceable constraint on gerrymanders. First, it directly tackles the Chief Justice’s fear of the judiciary appearing partisan, observing that the same fear would exist if the Constitution explicitly banned gerrymanders and explaining why an implicit ban should be no less judicially enforceable than an explicit ban under Marbury v. Madison. Second, invoking the idea of “institutional forbearance” in the important new book How Democracies Die, the essay shows how the Elections Clause can be construed to protect congressional districting from abuses of legislative discretion committed by state legislatures. Together, these two points lead to a third: the most essential duty of the Court, according to originalist theories of constitutional interpretation, is to preserve the Constitution against changes that would undermine its provisions or its overall core commitment to the creation of a federal republic for the United States; thus, insofar as virulent gerrymanders increasingly threaten the measure of popular sovereignty that elections to the federal House of Representatives were designed to achieve, the preservationist function of originalism requires judicial invalidation of those gerrymanders.

Drawing the Lines: Constraints on Partisan Gerrymandering in U.S. Politics. By Nicholas R. Seabrook. Ithaca, NY: Cornell University Press, 2017. 160p. $49.95 cloth.

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Gerrymandering and Conceit: The Supreme Court's Conflict With Itself

In November 2016, a federal court struck as unconstitutional Wisconsin’s redistricting map under both the First Amendment and the Equal Protection Clause. The court’s decision in Whitford v. Gill marks the first time a federal court invalidated a redistricting map as unconstitutional for partisan gerrymandering in over thirty years. Wisconsin has appealed the decision to the United States Supreme Court, which recently granted review. The Supreme Court has long held that extreme partisan gerrymandering violates equal protection but has simultaneously refused to determine the merits of gerrymandering disputes, instead labeling them as non-justiciable political questions. In particular, the Court has maintained that no manageable standard yet exists by which the Court could implement the promise of equal protection to partisan redistricting. This Article analyzes the manageable standard requirement, revealing the Court’s failure to define the term and that the Court has applied the manageability requirement haphazardly. Scores of court-made standards either over- or under-enforce the constitutional norm they purport to implement. Why is “fairness” a workable standard in one context but not another? How are standards that measure one’s shocked conscious, or weigh the totality of the circumstances judicially manageable? Importantly, a common thread connects the Court’s use of the manageability requirement to its insecurity in exercising judicial review, indicating that the Court often applies the manageability requirement when particularly insecure in exercising the judicial function. Recast in this light, the question of Court engagement in gerrymandering disputes turns on the propriety of Court intervention to address artificial obstacles that disrupt democratic functionality. The Court should no longer hide behind the manageability barrier because court intervention to ensure democracy’s proper functioning was (1) anticipated by the Framers, (2) memorialized in the Constitution’s form and structure, and (3) exercised by the Court without loss of judicial legitimacy in analogous contexts. This Article posits that judicial intervention to unblock the avenues of political change is one of the Court’s central responsibilities, that in similar contexts the Court has recognized as much, and that it should do so again in Whitford.