UC Law Constitutional Quarterly


In Gill v. Whitford, the Supreme Court dismissed a challenge to Wisconsin’s state legislative map based upon a lack of standing. While the plaintiffs alleged that the statewide map violated the Equal Protection Clause of the Constitution by being gerrymandered to asymmetrically advantage one political party over the other, the Court held that such allegations were insufficient to state a personal, individualized injury under Article III’s Case or Controversy Clause. Since the plaintiffs had not alleged that their voting power in their particular legislative districts had been diluted, the Court found that the plaintiffs’ complaint stated only a “generalized grievance” incapable of giving them standing under Article III. The Supreme Court was likely correct to find the plaintiff’s proof was incomplete, but that is only because the principal metric employed in the case—the much-celebrated “efficiency gap”—is by definition capable of identifying partisan bias only in a statewide map and not on a district-by-district basis. In this Article, we propose a methodology by which plaintiffs can plausibly demonstrate the impact of partisan bias on a district-by-district basis by calculating the district’s “vote dilution index”: the percentage of voters who could be drawn into competitive districts but who have instead been “cracked” or “packed” into a noncompetitive district by mapmakers. The application of that metric reveals not only that the prevalence of partisan gerrymandering is more significant and, in many districts, more extreme than previously known, but the precise degree to which each district has been skewed to promote the dominance of one of the major political parties at the expense of the power of individual voters. By permitting comparison of the degree of vote dilution between districts while simultaneously accounting for the limitations imposed by geographical clustering of voters, the “vote dilution index” opens the door to partisan gerrymandering claims that the Supreme Court left ajar in Whitford.