The Junk Science at the Heart of the Gerrymandering Case

Earlier this month, the Supreme Court heard oral arguments in Gill v. Whitford, a case in which University of Wisconsin professor William Whitford and a group of plaintiffs (all Democratic voters in the state) contend that the drawing up of Wisconsin’s state legislative districts was an unconstitutional gerrymander.

The Supreme Court has intervened in gerrymandering complaints in the past, but those cases had to do with racial discrimination or malapportionment. That is, the Court has struck down legislative maps that distribute black voters in ways that minimize their electoral power. In the Wisconsin case, race and ethnicity are not at issue, at least not directly. The plaintiffs are asking the Court to invalidate district lines drawn by the state legislature in 2011 because those lines favor Republicans over Democrats.

Based on the oral arguments, the case is another that divides the Court along ideological lines. The four conservative justices—Chief Justice John Roberts, Clarence Thomas, Samuel Alito, and Neil Gorsuch—seem skeptical that the Court should intervene in such matters. It is better, instead, to leave partisan gerrymanders to the political process. The liberals—Ruth Bader Ginsburg, Stephen Breyer, Sonia Sotomayor, and Elena Kagan—appear eager to involve the Court in the process. Once again, that leaves Justice Anthony Kennedy in the middle, the crucial fifth vote who will decide which way the Court swings.

Kennedy has previously expressed openness to the Court’s involving itself in resolving partisan gerrymandering. In Vieth v. Jubelirer (2004), though the Court declined to rule on the constitutionality of Pennsylvania’s congressional redistricting, Kennedy indicated that the justices might have a role to play if they could find a workable standard to apply.

This is what makes the Wisconsin case especially important. The plaintiffs claim to have put forward such a standard—based on a metric known as the “efficiency gap”—that, they argue, is a simple, intuitive, and broadly applicable tool to find the effects of a gerrymander.