NRCC General Counsel and RNLA member Chris Winkelman and Holtzman Vogel Josefiak Torchinsky PLLC attorney Phil Gordon wrote about the serious problems with the efficiency gap analysis used by the lower court in Gill v. Whitford, which the Supreme Court will hear next term (internal headings omitted):
Just when plaintiffs, distraught that their failures at the ballot box cannot be saved by wins in the courtroom, had given up hope of ever finding a standard that would meet with the approval of five justices, come the plaintiffs in this case with a “scientific” method of determining impermissible partisan gerrymandering: the so-called “efficiency gap.” . . . The efficiency gap counts any vote as wasted if that vote was for a losing candidate or was more than what the prevailing candidate needed to win a given election (i.e., 50 percent of the vote plus one in a two-party election). These supposedly wasted votes are then divided by the total number of votes in an election, and the resulting number is the misleadingly named efficiency gap. However, even a cursory inspection of this so-called methodology reveals analytical flaws and partisan skullduggery too blatant to pass constitutional muster or stand up to common sense.
A fundamental problem with the efficiency gap is that it treats voters as monolithic blocs who vote party above all else. This assumption is contrary to reality. The efficiency gap, much like most statistical election models, attempts to predict the future. The efficiency gap is particularly bad at predicting the future because it relies on the results of a single statewide election for its calculation, aggregating a series of district-by-district elections. As recent elections have laid bare, the assertions that voters 1) will never change their mind, and 2) vote for the party only and not the candidate, are not supported by actual election outcomes. The efficiency gap does not account for vote switchers or split-ballot voting. In fact, the authors of the efficiency gap state that a gap of eight percent ought to be sufficient to render a legislative reapportionment a justiciable partisan gerrymander. . . .
The efficiency gap is mired in a plethora of problems, both methodological and quantitative. There is not nearly enough time or space to fully document them all here. The biggest single problem with the efficiency gap is that it assumes that political populations are relatively evenly dispersed geographically. Scientific literature and common-sense experience do not support that assumption. Currently, Democrats in the United States are mostly clustered in urban areas, while Republicans tend to inhabit more suburban and rural areas. . . . This asymmetrical grouping of voters has real-world consequences on attempts to form legislative districts using traditional districting criteria (compactness, contiguity, equal population etc.). Traditional districting criteria exist, at least in part, to give courts and map makers some guidelines for evaluating maps to ensure compliance with the equal protection clause of the Constitution. Given the focus that the Supreme Court has placed on the shapes of districts, the lower court could be forgiven for rejecting the challenged maps in Wisconsin’s Act 43 if the shapes of the district boundaries were particularly egregious. They were not. The plaintiffs in this case even conceded that the challenged districts were relatively compact and contiguous and that they met the requirements of “one-person one-vote.” . . . However, the two-judge district court majority, in a novel approach, eschewed traditional districting criteria in favor of the efficiency-gap test in order to rule that Republicans had given themselves an overwhelming unconstitutional electoral advantage over the life of Act 43.
The district court ignored the actual impact that its decision will have. Compactness, as Kennedy said in Vieth, helps Republicans because of the effect of political geography. In order to comply with this new efficiency-gap standard, the Wisconsin General Assembly would have to create maps that are less compact and contiguous. The Supreme Court has long lamented the snakes, “sacred Mayan bird[s],” “Rorschach ink-blot test[s]” and “uncouth twenty-eight-sided figure[s]” that creative cartographers have made into legislative districts. Yet, in this case, the challengers are asking the court to force state legislatures across the country to fix the Democrats’ political geography problem by ignoring years of precedent to make less compact and contiguous maps. The court should roundly reject this invitation.
The NRCC's amicus brief in Gill v. Whitford fully analyzes the practical problems with the efficiency gap analysis and outlines how the plaintiff's methodology, adopted by the district court, violates established Supreme Court case law on redistricting. We will follow interesting developments in Gill v. Whitford as it goes to argument next term.