Gill v. Whitford, 585 U.S. 48 (2018), was a United States Supreme Court case involving the constitutionality of partisan gerrymandering.

[1] That issue was later resolved in Rucho v. Common Cause, in which the Court decided that partisan gerrymanders presented a nonjusticiable political question.

During the Court's deliberations, it also accepted to hear the merits of another partisan gerrymandering case, Benisek v. Lamone,[2] related to the 2011 redistricting of Maryland's 6th congressional district, for which it heard oral arguments in March 2018.

While the majority of political scientists agree that Wisconsin's map was heavily biased, it was expected that the case would center on whether the efficiency gap measures and other metrics provided by political scientists meet the criteria that Justice Anthony Kennedy set forth in his concurring opinion in Vieth v. Jubelirer (2004), a previous Supreme Court case dealing with partisan gerrymandering.

Notably, the practice of gerrymandering, redistricting that draws convoluted district boundaries to favor or disadvantage certain socioeconomic groups, has frequently been used to improve the party's chances of securing elections in the future.

However, the ruling has yet to adopt a standard for determining partisan gerrymandering in redistricting, with proposed tests being too ambiguous for the courts to apply.

[3][4] In the decision for the 2004 case Vieth v. Jubelirer, which ruled that perceived partisan gerrymandering in Pennsylvania was not unconstitutional, the nine Justices were split.

[8] The case was filed by the Campaign Legal Center (CLC), representing twelve plaintiffs that were registered Democrats.

[9] The lead plaintiff, Professor William Whitford, from University of Wisconsin, stated, "In a democracy citizens are supposed to choose their legislators.

"[14][7] The panel judged these prongs based on whether they created an entrenchment of power, specifically defined as "making that party—and therefore the state government—impervious to the interests of citizens affiliated with other political parties",[15] which has been the basis for unconstitutional gerrymandering in the past.

"[16][7] The panel also used the Efficiency Gap measure, developed in 2014 by law professor and lead attorney for the plaintiffs Nicholas Stephanopoulos, and political scientist Eric McGhee.

[5] Judge William C. Griesbach dissented, believing that there were more appropriate measures they could take to prevent partisan gerrymandering, such as requiring a non-partisan redistricting panel.

[27] These scholars introduced other metrics besides the efficiency gaps that equally demonstrated the partisan bias in Wisconsin's plan, which were expected to be considered to be evaluated by the Justices.

[23] Oral arguments were given by Paul Smith of the CLC, representing the original plaintiffs, and by Misha Tseytlin, the Wisconsin Solicitor General.

[29] Smith argued that while the Court's previous attempts to regulate partisan gerrymandering failed due to lack of a usable measure, modern statistics and advanced computing available today made it very easy for the Wisconsin Republicans to create their favorable redistricting plan, but these tools would be just as useful to determine when partisan gerrymandering had occurred.

The four Justices that were considered liberal appeared to side with the original plaintiffs in arguing that the redistricting plan was biased, with Justice Ruth Bader Ginsburg proposing that if they did not intervene here, Republicans would likely be able to stack other states in a similar manner, and it would de-incentive voters not favored by such redistricting plans to vote.

[30] The decision was expected to hinge on Justice Kennedy, who had held a middle ground in Vieth and wrote in his opinion about the need to find a "manageable standard" to determine if a partisan gerrymandering had occurred.

Instead, Roberts suggested there may be other forms of harm that the plaintiffs could demonstrate, such as by considering the impact of the redistricting on the entire state rather than one district.

Justice Elena Kagan wrote a concurring opinion, joined by Ruth Bader Ginsburg, Stephen Breyer, and Sonia Sotomayor, which identified steps that the plaintiffs could use in the remanded case to demonstrate harm.