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As the nation's court of last resort, the U.S. Supreme Court has heard various cases throughout its history regarding the drawing of congressional and legislative district lines. When the high court issues rulings in these cases, the precedents established affect redistricting practices throughout the country.

This article summarizes 18 noteworthy redistricting cases that the court has heard since 1946, including links to additional information about each of them.

Is there a case you think should be included on this list? Click here to let us know.

To see these cases displayed in a timeline, see this article.

Redistricting cases by year

This section lists 18 summaries of noteworthy redistricting cases heard by the U.S. Supreme Court in reverse chronological order.

The decision to include a case as noteworthy is based on Ballotpedia's criteria for inclusion, which were drafted and adopted in April 2017. These criteria were developed by our professional writers and editors and approved by our senior editorial team. For more information on our selection criteria for noteworthy cases, click here.

Alexander v. South Carolina State Conference of the NAACP (2024)

See also: Alexander v. South Carolina State Conference of the NAACP

Alexander v. South Carolina State Conference of the NAACP is a case that was decided by the Supreme Court of the United States on May 23, 2024, during the court's October 2023-2024 term. The case was argued before the Court on October 11, 2023.

The Court partially reversed the U.S. District Court for the District of South Carolina's ruling and partially remanded the case for further proceedings in a 6-3 ruling, holding "the District Court’s finding that race predominated in the design of District I in the Enacted Plan was clearly erroneous. ... Because the same findings of fact and reasoning that guided the court’s racial-gerrymandering analysis also guided the analysis of the Challengers’ independent vote-dilution claim, that conclusion also cannot stand. ... In light of these two errors in the District Court’s analysis, a remand is appropriate."^[1] Justice Samuel Alito delivered the majority opinion of the court. Justice Clarence Thomas filed an opinion concurring in part. Justice Elena Kagan filed a dissenting opinion, joined by Justices Sonia Sotomayor and Ketanji Brown Jackson. Click here for more information about the ruling.

For more information and background about the issues presented regarding redistricting in South Carolina after the 2020 census, click here.

Moore v. Harper (2022)

See also: Moore v. Harper

Moore v. Harper is a case that was decided by the Supreme Court of the United States on June 27, 2023, during the court's October 2022-2023 term. The case was argued before the Supreme Court of the United States on December 7, 2022.

Merrill v. Milligan (2022)

See also: Merrill v. Milligan

Note: This case was previously known as Merrill v. Milligan; it became Allen v. Milligan when Wes Allen became the Alabama Secretary of State.

Allen v. Milligan is a case that was decided by the Supreme Court of the United States on June 8, 2023, during the court's October 2022-2023 term. The case was argued before the court on October 4, 2022. It was consolidated with Allen v. Caster. In a 5-4 opinion, the court affirmed the judgment of the United States District Court for the Northern District of Alabama, holding that the plaintiffs showed a reasonable likelihood of success concerning their claim that Alabama's redistricting map (HB1) violates Section 2 of the Voting Rights Act. Chief Justice John Roberts delivered the opinion of the court.^[3][4]

Benisek v. Lamone (2017)

See also: Benisek v. Lamone

Benisek v. Lamone is a case that was decided by the Supreme Court of the United States on June 18, 2018, which held that the plaintiffs, seven Republican voters in Maryland, failed to demonstrate that they would suffer irreparable harm if an injunction was not granted barring enforcement of a new congressional district map in the state. The Supreme Court affirmed the district court's decision to deny the plaintiffs an injunction.

On December 8, 2017, the court added the case to its docket for the term, consenting to a hearing on the merits. Oral argument in the case took place on March 28, 2018. The judgment under review came from the United States District Court for the District of Maryland.^[6]

Gill v. Whitford (2017)

See also: Gill v. Whitford

Gill v. Whitford is a case decided by the Supreme Court of the United States on June 18, 2018, which held that the plaintiffs, twelve registered Democratic voters in Wisconsin, failed to show sufficient evidence of personal harm to have standing to challenge the state's legislative redistricting plan as an unconstitutional partisan gerrymander. The case was remanded to the district court. Argument in the case was held on October 3, 2017. The judgment under review was from the United States District Court for the Western District of Wisconsin.

In a July 21, 2017, talk addressing Duke University Law School's D.C. Summer Institute on Law and Policy, Justice Ruth Bader Ginsburg suggested that Gill was "perhaps the most important" case the court would hear during its October 2017 term, noting that "so far, the court has held race-based gerrymandering unconstitutional but has not found a manageable, reliable measure of fairness for determining whether a partisan gerrymander violates the Constitution."^[7][8][9]

Harris v. Arizona Independent Redistricting Commission (2016)

See also: Harris v. Arizona Independent Redistricting Commission

Harris v. Arizona Independent Redistricting Commission is a case decided by the United States Supreme Court on April 20, 2016. At issue was the constitutionality of state legislative districts that were created by the commission in 2012. The plaintiffs, a group of Republican voters, alleged that "the commission diluted or inflated the votes of almost two million Arizona citizens when the commission intentionally and systematically overpopulated 16 Republican districts while under-populating 11 Democrat districts." This, the plaintiffs argued, constituted a partisan gerrymander. The plaintiffs claimed that the commission placed a disproportionately large number of non-minority voters in districts dominated by Republicans; meanwhile, the commission allegedly placed many minority voters in smaller districts that tend to vote Democratic. As a result, the plaintiffs argued, more voters overall were placed in districts favoring Republicans than in those favoring Democrats, thereby diluting the votes of citizens in the Republican-dominated districts. The defendants countered that the population deviations resulted from legally defensible efforts to comply with the Voting Rights Act and obtain approval from the United States Department of Justice. At the time of redistricting, certain states were required to obtain preclearance from the justice department before adopting redistricting plans or making other changes to their election laws—a requirement struck down by the United States Supreme Court in Shelby County v. Holder (2013).^[11]

Evenwel v. Abbott (2016)

See also: Evenwel v. Abbott

Evenwel v. Abbott is a case decided by the United States Supreme Court in 2016. At issue was the constitutionality of state legislative districts in Texas. The plaintiffs, Sue Evenwel and Edward Pfenninger, argued that district populations ought to take into account only the number of registered or eligible voters residing within those districts. Total population counts have typically been used for redistricting purposes. Total population tallies include non-voting residents, such as illegal immigrants, prisoners and children. The plaintiffs alleged that this tabulation method dilutes the voting power of citizens residing in districts that are home to smaller concentrations of non-voting residents. Oral arguments took place on December 8, 2015.^{[14][15][13][16]}

Arizona State Legislature v. Arizona Independent Redistricting Commission (2015)

See also: Arizona State Legislature v. Arizona Independent Redistricting Commission

Arizona State Legislature v. Arizona Independent Redistricting Commission is a case that was decided by the United States Supreme Court. At issue was the constitutionality of the Arizona Independent Redistricting Commission, which was established by state constitutional amendment in 2000. According to Article 1, Section 4, of the United States Constitution, "the Times, Places and Manner of holding Elections for Senators and Representatives shall be prescribed in each State by the Legislature thereof." The state legislature argued that the use of the word "legislature" in this context is literal; therefore, only a state legislature may draw congressional district lines. Meanwhile, the commission contended that the word "legislature" ought to be interpreted more broadly to mean "the legislative powers of the state," including voter initiatives and referenda.^[15][21]

Shelby County v. Holder (2013)

See also: Shelby County v. Holder

Shelby County v. Holder, a major case decided by the United States Supreme Court in 2013, declared Section 4(b) of the Voting Rights Act of 1965 unconstitutional, removing preclearance requirements for all jurisdictions unless the preclearance formula of Section 4(b) is updated by Congress.

Vieth v. Jubelirer (2004)

See also: Vieth v. Jubelirer

Vieth v. Jubelirer was a case decided by the Supreme Court of the United States in 2004. The case was brought by a group of Pennsylvania Democrats who alleged that the state legislature, controlled by Republicans at the time of the 2000 redistricting cycle, had developed a congressional district map that constituted an illegal partisan gerrymander. On April 28, 2004, the court issued a split decision with no majority opinion, declining to intervene in the case. Consequently, the case established no precedent regarding claims of unconstitutional partisan gerrymandering.^[25]

Davis v. Bandemer (1986)

See also: Davis v. Bandemer

Davis v. Bandemer was a case decided by the Supreme Court of the United States in 1986. The case was brought by a group of Indiana Democrats who alleged that the apportionment of Indiana's state legislature diluted the impact of Democratic votes in key districts in violation of the Equal Protection Clause of the Amendment XIV, United States Constitution. On June 30, 1986, the high court ruled that Indiana's district plans did not constitute an illegal partisan gerrymander. The court did, however, maintain that partisan gerrymandering claims are justiciable under the Equal Protection Clause (i.e., that federal courts have the right to intervene in such matters).^[26]

Thornburg v. Gingles (1986)

See also: Thornburg v. Gingles

Thornburg v. Gingles, a case decided by the United States Supreme Court in 1986, rendered districts of the General Assembly of North Carolina invalid on the basis that the districts impaired the ability of black voters to elect candidates of their choice. In this ruling, the high court established three criteria for analyzing claims of vote dilution.^[27]

Avery v. Midland County (1968)

See also: Avery v. Midland County

Avery v. Midland County was a case decided by the Supreme Court of the United States in 1968. The case was brought by Hank Avery, then-mayor of Midland, Texas, who alleged that the apportionment of Midland County's Commissioners Court violated the Equal Protection Clause of the Fourteenth Amendment to the United States Constitution due to population disparities between the districts from which the commissioners were elected. On April 1, 1968, the high court ruled 5-3 in favor of Avery.^[28]

Reynolds v. Sims (1964)

See also: Reynolds v. Sims

Reynolds v. Sims is a case decided on June 15, 1964, by the United States Supreme Court holding that state legislative districts should be made up of equal populations. The case concerned whether the apportionment of Alabama's state legislature violated the Equal Protection Clause of the Fourteenth Amendment of the U.S. Constitution. The Supreme Court affirmed the decision of the United States District Court for the Middle District of Alabama.^[29][30][31]

Wesberry v. Sanders (1964)

See also: Wesberry v. Sanders

Wesberry v. Sanders was a case decided by the Supreme Court of the United States in 1964. The case was brought by James P. Wesberry, Jr., against Georgia Governor Carl Sanders. Wesberry alleged that the population of the Georgia's Fifth Congressional District, his home district, was two to three times larger than that of other districts in the state, thereby diluting the impact of his vote relative to other Georgia residents in violation of the United States Constitution. On February 17, 1964, the court ruled 6-3 in favor of Wesberry, finding that congressional districts must have nearly equal populations in order to ensure that "as nearly as is practicable, one man's vote in a congressional election is to be worth as much as another's."^[32][33]

Gray v. Sanders (1963)

See also: Gray v. Sanders

Gray v. Sanders was a case decided by the Supreme Court of the United States in 1963. The case was brought by a Georgia voter who alleged that the state's system for counting primary votes (described in court documents as the county unit voting system) violated the Equal Protection Clause of the Amendment XIV, United States Constitution, giving disproportionate influence to voters in rural counties. On March 18, 1963, the Supreme Court of the United States ruled 8-1 that the county unit voting system violated the Equal Protection Clause.^[34][35]

Baker v. Carr (1962)

See also: Baker v. Carr

Baker v. Carr is a case decided by the Supreme Court of the United States in 1962. The case was brought by a group of Tennessee voters who alleged that the apportionment of Tennessee's state legislature failed to account for significant population variations between districts, violating the Equal Protection Clause of the Fourteenth Amendment to United States Constitution. A federal court dismissed the complaint, finding that it lacked jurisdiction to intervene in such matters. On March 26, 1962, the Supreme Court of the United States ruled 6-2 in favor of the plaintiffs, finding that apportionment cases are justiciable (i.e., that federal courts have the right to intervene in such cases).^[36]

Colegrove v. Green (1946)

See also: Colegrove v. Green

Colegrove v. Green was a case decided by the Supreme Court of the United States in 1946. The case was brought by three Illinois voters who alleged that the state's congressional districts "lacked compactness of territory and approximate equality of population," violating the United States Constitution. The high court affirmed the decision of a federal district court, which had dismissed the complaint on the grounds that no requirements relating to compactness, contiguity, or equality of population existed within the canon of federal law.^[37]

See also

• Redistricting
• Gerrymandering
• State-by-state redistricting procedures

Footnotes