With increasing partisan polarization and reduction in voting across party lines, redistricting schemes implemented by state legislatures are one of the most important tools legislatures can use to entrench a political party in power. From drawing boards with physical maps of electoral districts, to using software to draw thousands of maps instantaneously, the means of redistricting have changed dramatically in the past couple of decades. Additionally, while the technology allowing political gerrymandering to become finely tuned has advanced, political checks on this scheme have diminished significantly.

Gerrymandering is the manipulation of electoral districts to increase the likelihood of a particular party winning the election for the district.[1] The Constitution apportions seats of the House of Representatives to the States on the basis of their population,[2] and grants to State Legislatures authority to determine the manner in which they conduct federal elections, subject to alterations by Congress.[3] However, beyond this, the Constitution has nothing to say about the districting methods used by States in conducting elections.

The most popular tool used in districting is Maptitude for Redistricting Software, created by the Caliper Corporation. The tool features mapping and Geographic Information System software, and “provides a complete set of mapping and spatial analysis functions, sophisticated geocoding, tools for complex data manipulation, and a large collection of nationwide geographic data.”[4] With the power of big data, legislators are now easily able to use information about age, race, sex, ethnicity, income, past election results, and more, to predict voting patterns. Legislators can then use algorithms that take into consideration this voting data along with other factors such as compactness, county and municipality boundaries, contiguity, and minority representation, to develop electoral maps that keep their party in power. These algorithms allow legislators to develop maps that are perfectly gerrymandered on party lines, but comply with districting requirements like equal population size, and those imposed by the Voting Rights Act of 1965.[5] This has resulted in a “winner’s bonus” in heavily gerrymandered states. For instance, in the 2012 elections, in six states (NC, VA, MI, OH, PA, FL, and IN) Republicans had a 76% advantage in seats in the House, despite only having an average margin of victory of 7% in total vote share.[6] With advancing software and increasing access to big data, redistricting along party lines has become easier than ever.

However, it is not all bad news. The same algorithms that are being exploited by these gerrymanders can be used to develop neutral electoral maps. Statisticians can put redrawn maps through simulations to determine how far they fall from a “fair” plan.[7] A tool developed by Harvard University, called Redist, can be used to create over 5,000 maps drawn on non-partisan lines.[8] These maps provide a neutral baseline to which redrawn maps can be compared and can check whether the chosen redistricting scheme is such an outlier to the extent that factors like party membership must have had an undue influence on district drawing.[9] This has been used as evidence of unlawful gerrymandering, leading to revision of unfair maps. For instance, in League of Women Voters of Ohio v. Ohio Redistricting Commission, the Ohio Supreme Court held that the redistricting plan was invalid because 5,000 other party-neutral maps that were drawn were not as favorable to Republicans as the proposed plan.[10] Similarly, in New York, the algorithm was used to show that the chosen map was an “extreme outlier,” reducing Republican seats from eight to four.[11] Thus, while technology has made partisan gerrymandering easier and more extreme than ever before, there is also an emerging opportunity to use software to test redistricted maps and challenge their fairness.

While the Constitution provides no guidelines about how legislatures should set up their districts, the Supreme Court has read the Equal Protection Clause to provide protections against the districting plans used by legislatures. In Baker v. Carr, the Supreme Court held that districts created by legislatures should be of equal population sizes to ensure votes have equal value. Additionally, Congress passed the Voting Rights Act in 1965 to protect against voter disenfranchisement and vote dilution through voting practices that discriminate on the basis of race, color, or membership in language minority groups.[12] However, most legislation surrounding voting rights and vote dilution have focused on racial gerrymandering and the use of processes and districting schemes to dilute votes of minority communities.

Partisan gerrymandering on the other hand has been held to be nonjusticiable by federal courts because of the lack of “judicially manageable standards.”[13] In Rucho v. Common Cause, Chief Justice Roberts held that the issue of partisan gerrymandering could instead be addressed by other institutions such as Congress, State Constitutions, and State Courts.[14] However, this limited protection against partisan gerrymandering is vulnerable. While the For the People Act, which bans partisan gerrymandering, has passed the House, the Act has been blocked in the Senate. Additionally, the likelihood that state legislatures will solve this issue is minimal given that gerrymandering allows “politicians [to] cherry-pick voters to ensure their reelection.”[15] State court checks on partisan gerrymandering are in peril as well. The Supreme Court will soon decide Moore v. Harper, which addresses the authority of North Carolina’s Supreme Court in striking down a congressional map that violates the state’s Constitution because of its extreme partisan gerrymandering.[16] The outcome of this case could impact the ability of constituents to turn to the courts for recourse in instances of extreme partisan gerrymandering, further limiting checks on the legislature's ability to entrench their party in power.

In light of these disappearing controls over extreme gerrymandering, advancement of technology that allows parties to redistrict with surgical precision threatens democracy. Currently, constituents can turn to their state courts to challenge extremely gerrymandered maps, but the outcome of Moore v. Harper will determine whether the public will be able to hold their representatives accountable and protect the value of their votes.



[1] https://en.wikipedia.org/wiki/Gerrymandering

[2] U.S. Const. art. 1, §2.

[3] U.S. Const. art. 1, §4.

[4] https://www.caliper.com/redistricting-software.htm

[5] https://www.theguardian.com/us-news/2021/aug/22/gerrymandering-us-electoral-districts-congress

[6] https://www.theatlantic.com/politics/archive/2017/10/gerrymandering-technology-redmap-2020/543888/

[7] https://news.harvard.edu/gazette/story/2022/11/an-algorithm-to-detect-gerrymandering/

[8] Id.

[9] Id.

[10] League of Women Voters of Ohio v. Ohio Redistricting Comm'n, 167 Ohio St. 3d 255 (2022).

[11] Matter of Harkenrider v. Hochul, 38 N.Y.3d 494, 506 (2022).

[12] https://naacp.org/find-resources/history-explained/legislative-milestones/voting-rights-act-1965

[13] Rucho v. Common Cause, 139 S. Ct. 2484, 2491 (2019).

[14] Id.

[15] Id at 2512.

[16] https://www.brennancenter.org/our-work/research-reports/moore-v-harper-explained