On October 3, the US Supreme Court will hear a case concerning the state of Wisconsin’s legislative districts that could resolve a pending constitutional crisis and dramatically improve electoral representation.

At the center of the dilemma is the applicability of a scientific standard to measure discrimination resulting from district boundary manipulation. What’s new in this case is that social scientists have developed a standard. But what the court will do with it is anybody’s guess. So let’s guess.

We have a scientific standard that is discernible and manageable

Social scientists have been hard at work since 2004, when the Supreme Court issued a fragmented, 5-4 decision in Vieth v Jubelier holding that “plaintiffs failed to establish a standard” to determine when partisan gerrymandering has gone too far The analytical tools for estimating various forms of partisan discrimination have dramatically improved since Vieth, as described in one of the many amicus briefs submitted to the court.

Consensus has emerged around partisan asymmetry as a scientific standard that is both discernible (logically grounded in constitutional protections) and manageable (so that courts can apply it). It measures any difference in the percentage of seats that a given percentage of voters (say 50%) receive, depending on what party they vote for. Asymmetries can be easily estimated with actual election results and computationally simulated vote swings across districts, along with measures of statistical confidence.

Similarly, the mean-median test, comparing each party’s actual vote share in its median district to overall mean vote share, is another way of estimating asymmetries between voters. There are important theoretical and methodological differences between various measures, including the efficiency gap, which compares “wasted” votes between parties. But all are empirically accurate at identifying partisan bias where it matters most: in competitive states where voters from one party have a major seat advantage.

However, the fact that a standard has emerged is no guarantee that it will be adopted. Attention will focus on convincing Justice Anthony Kennedy, who welcomed the discovery of “workable standards” as the swing vote in Vieth. His level of satisfaction with these results is likely to drive the justices toward one of the following three scenarios.

Scenario one: Kennedy keeps the Supreme Court out of the thicket

In a crushing defeat to defendants and electoral reformers in both parties, Justice Kennedy is unpersuaded, leading to another 5-4 decision in which the more liberal justices (Ginsburg, Breyer, Kagen, and Sotomayor) agree that symmetry is a workable standard, but they don’t have the votes. A plurality of the court’s conservatives either dismiss outright the idea that courts ought to be entering the political thicket of partisan competition, or they reassert a version of Antonin Scalia’s Vieth opinion, holding that symmetry is a standard measuring discrimination against parties, not people, with only the latter having constitutional rights (although it has been demonstrated that symmetry reflects individual political equality).

Kennedy writes a concurrent opinion with the conservatives, articulating a more nuanced failure on the part of plaintiffs to specify “how much is too much” as both plaintiffs and most of the scientific briefs submitted explicitly placed responsibility for specifying a threshold of unconstitutional discrimination with the courts. Kennedy could also point to in-fighting among political scientists over our favored measures as lack of consensus. Talk about a tragedy of the commons.

Scenario two: Wisconsin’s districts are thrown out, but the real work is left for future courts

A focused interrogation by Kennedy results in a majority opinion that overturns Wisconsin’s gerrymandered map. Several measures of bias are incorporated into a multi-pronged test that verifies if 1) the district boundaries caused the observed discrimination (asymmetry), and 2) the extent of asymmetry is not likely to be reduced through changing voter preferences. That is, even a “wave” of public opposition would allow the entrenched party to hold power.

However, the majority does not go so far as to prescribe a general threshold for “how much is too much” gerrymandering. There is no precise level of necessary asymmetry, or responsiveness, or competitiveness specified that constitutes a violation of equal protection or free speech. Standards are left to emerge through future cases, of which there are many. Some version of this outcome seems most likely, given the scientific consensus, the level of extreme gerrymandering witnessed in the 2011 redistricting cycle, and the bipartisan response to it.

Scenario three: A precise standard is adopted with clear direction for lower courts

In this third, and probably least likely scenario, the justices not only establish a multi-prong test to identify unconstitutional partisan discrimination, they also specify the degree of relief that discriminated voters are entitled to. The question of “how much is too much” discrimination is answered precisely through a specific measure, either when asymmetry would result in a single seat change, or change in majority control of a legislative body, or a mean-median difference greater than 5 percent (which is rare) or an efficiency gap greater than 7 percent (which is also rare), etc.

The court could apply the breadth of knowledge that we have to specify thresholds of tolerance, below which any hypothetical districting plan would be invalidated. But because the process of districting involves maximizing numerous conflicting principles, such as geographic compactness and bias, the justices are unlikely to go this far, at this time. And only time will tell if a more cautious approach will be adequate.

Can a constitutional crisis be averted?

If the Supreme Court fails to rein in partisan gerrymandering, the fundamental democratic principle of majority rule is undermined. The Electoral College has enabled minority control over the executive, and majority control of the Senate has been determined by a minority of voters due to the underrepresentation of large states.

In 2018, a majority as large as 56 percent of Americans could vote against the governing party (currently the Republican Party) in the House of Representatives, while they retain control of a majority of (gerrymandered) seats. It is up to the Supreme Court to re-establish a republic “of the people.”

Posted in: Science and Democracy Tags: gerrymandering, supreme court



Support from UCS members make work like this possible. Will you join us? Help UCS advance independent science for a healthy environment and a safer world.