But Gill v. Whitford’s rise to the top of the Supreme Court docket was all the more remarkable because the plaintiffs’ argument—that Wisconsin Republicans drew state Assembly maps that diluted votes based on a partisan, not racial, bias—is one for which federal courts are considerably less prepared. Supreme Court precedent holds that maps drawn to maximize partisan advantage, pack members of one party into certain districts, or dilute them across others, can be unconstitutional. But that Court has also found that partisan advantage in redistricting is acceptable, and hasn’t agreed on how to measure that advantage or on when it might go beyond the pale. Indeed, there are still substantive arguments on whether the Court can even make such a decision. All of these factors have made serious partisan gerrymandering challenges rare.
As the tools for redistricting have become increasingly sophisticated and capable of producing partisan advantages, however, so have the analytic tools for identifying gerrymanders. Those tools were key for the plaintiffs in the Gill v. Whitford case. In their arguments, new ways of identifying gerrymanders gave them a way to spot partisan gerrymanders, and identify tipping points where those gerrymanders constituted constitutional infringement. There were supercomputer simulations. There were different measures of just how many seats devious gerrymandering schemes purloined from opposing parties. Chief among those was the “efficiency gap,” a metric that allows observers to calculate “wasted votes,” those that go to losing candidates or those that would’ve won anyways. Those tests—which found that the Wisconsin GOP had built enough advantage to continue to hold a majority of seats even if they don’t get 50 percent of the votes—were enough for a federal district court to strike the maps down.
Upon appeal, those tests were not enough for the Supreme Court to uphold that decision. Specifically, the justices unanimously agreed that the plaintiffs’ sophisticated tests of partisan gerrymandering pick up damage done to opposing parties, but didn’t quite show how Wisconsin’s politically biased map infringes upon individual constitutional rights, and how it burdens individual voters. Since gerrymandering rulings under the Voting Rights Act derive from the Equal Protection clause, tests that prove a violation of an individual’s civil rights are critical to making the rulings stick.
While voting-rights groups hoping for a firm precedent-setting decision before the next round of map-drawing in 2021 expressed disappointment with the Court’s decision, it clearly doesn’t mean the end of the line for partisan gerrymandering arguments in federal courts. For one, plaintiffs could reconfigure their arguments to again meet the district court’s—and presumably, the Supreme Court’s—standard. Also, on the same day, the Supreme Court ruled in the Benisek v. Lamone case, a partisan gerrymandering case in Maryland in which Republican plaintiffs filed suit against Democratic mapmakers, whom the GOP argues retaliated against Republican voters in the 6th district by diluting their votes with the 2011 congressional map. The Supreme Court’s ruling essentially allows that case to go to trial in the lower court. Additionally, the high court is now primed to take on a consolidated challenge to partisan-aligned maps in North Carolina that were created as a direct response to its earlier decision on racial gerrymandering in the state.