As the 2020 round of redistricting approaches, these decisions are likely to be of particular interest to Congress. During its current term, the Court has decided one case regarding the degree to which racial considerations are permitted to impact how district lines are drawn and is considering another such case. Furthermore, the Supreme Court is currently considering an appeal from a three-judge federal district court ruling involving partisan gerrymandering. This case presents the Court with an opportunity to establish a standard for determining what constitutes unconstitutional partisan gerrymandering. The report then analyzes key foundational and recent Supreme Court and lower court redistricting decisions addressing four general topics: (1) the constitutional requirement of population equality among districts; (2) the intersection between the Voting Rights Act and the Equal Protection Clause, also known as claims of racial gerrymandering; (3) the justiciability of partisan gerrymandering; and (4) the constitutionality of state ballot initiatives providing for redistricting by independent commissions. In addition to various state processes, the legal framework for congressional redistricting involves constitutional and federal statutory requirements. This includes congressional redistricting plans. Equality Standard: One Person, One Vote

The Supreme Court has interpreted the Constitution to require that each congressional district within a state contain an approximately equal number of persons. This requirement is sometimes referred to as the "equality standard" or the principle of "one person, one vote." In several cases since 1964, the Supreme Court has described the extent to which precise or ideal mathematical population equality among districts is required. It is important to note that for congressional districts, less deviation from precise equality has been held by the Court to be permissible than is permissible for state legislative districts. Equal Protection and the Voting Rights Act

Much of the Supreme Court's redistricting jurisprudence has been prompted by disputes concerning the interplay between the requirements of the VRA and the constitutional standards of equal protection. A majority-minority district is one in which a racial or language minority group comprises a voting majority. The Court further listed the following factors, which originated in legislative history materials accompanying enactment of Section 2, as relevant in assessing the totality of the circumstances: 
1. the extent of any history of official discrimination in the state or political subdivision that touched the right of the members of the minority group to register, to vote, or otherwise to participate in the democratic process; 2. the extent to which voting in the elections of the state or political subdivisions is racially polarized; 3. the extent to which the state or political subdivision has used unusually large election districts, majority vote requirements, anti-single shot provisions, or other voting practices or procedures that may enhance the opportunity for discrimination against the minority group; 4. if there is a candidate slating process, whether the members of the minority group have been denied access to that process; 5. the extent to which members of the minority group in the state or political subdivision bear the effects of discrimination in such areas as education, employment and health, which hinder their ability to participate effectively in the political process; 6. whether political campaigns have been characterized by overt or subtle racial appeals; [and] 7. the extent to which members of the minority group have been elected to public office in the jurisdiction. These cases are often referred to as "racial gerrymandering" claims because the plaintiffs argue that race was improperly used in the drawing of district boundaries. In conclusion, while the VRA may require, under certain circumstances, the creation of one or more "majority-minority" districts in a congressional redistricting plan in order to prevent the denial or abridgement of the right to vote based on race, color, or membership in a language minority, redistricting maps are also subject to the constitutional standards of equal protection. If race is the predominant factor in the drawing of district lines, above other traditional redistricting considerations, then the state must demonstrate that it had a compelling governmental interest in creating a majority-minority district and the redistricting plan was narrowly tailored to further that interest. While leaving open the possibility that a claim of unconstitutional partisan gerrymandering could be within the scope of judicial review, as discussed below, the Supreme Court has been unable to decide on a manageable standard for making such a determination. However, the Supreme Court disagreed. Interpreting such requirements, in a series of cases and evolving jurisprudence, the U.S. Supreme Court has issued rulings that have significantly shaped how congressional districts are drawn and the degree to which challenges to redistricting plans may be successful. Finally, a 2015 Supreme Court ruling held that the Elections Clause of the Constitution permits states to create, by ballot initiatives and referenda, nonpartisan independent commissions for drawing congressional districts.
In addition to various state processes, the legal framework for congressional redistricting involves constitutional and federal statutory requirements. Interpreting these requirements, in a series of cases and evolving jurisprudence, the U.S. Supreme Court has issued rulings that have significantly shaped how congressional districts are drawn and the degree to which challenges to redistricting plans may succeed. As the 2020 round of redistricting approaches, foundational and recent rulings by the Court regarding redistricting are likely to be of particular interest to Congress. This report analyzes key Supreme Court and lower court redistricting decisions addressing four general topics: (1) the constitutional requirement of population equality among districts; (2) the intersection between the Voting Rights Act and the Equal Protection Clause; (3) the justiciability of partisan gerrymandering; and (4) the constitutionality of state ballot initiatives providing for redistricting by independent commissions.
The Supreme Court has interpreted the Constitution to require that each congressional district within a state contain approximately an equal number of persons. This requirement is sometimes referred to as the "equality standard" or the principle of "one person, one vote." In several cases, the Supreme Court has described the extent to which population equality among districts is required. For congressional districts, less deviation from precise equality has been held by the Court to be permissible than is permissible for state legislative districts.
In addition, congressional districts are required to comply with Section 2 of the Voting Rights Act (VRA), which prohibits any voting qualification or practice that results in the denial or abridgement of the right to vote based on race, color, or membership in a language minority. This includes congressional redistricting plans. Under certain circumstances, the VRA may require the creation of one or more "majority-minority" districts, in which a racial or language minority group comprises a voting majority. However, under the Supreme Court's interpretation of the Equal Protection Clause of the Fourteenth Amendment, if race is the predominant factor in the drawing of district lines, then a "strict scrutiny" standard of review applies. To withstand strict scrutiny in this context, the state must demonstrate that it had a compelling governmental interest in creating a majority-minority district and the redistricting plan was narrowly tailored to further that compelling interest. These cases are often referred to as "racial gerrymandering" claims because the plaintiffs argue that race was improperly used in the drawing of district boundaries. Much of the Supreme Court's redistricting jurisprudence has been triggered by disputes involving the intersection between requirements under the VRA and the constitutional standards of equal protection. For example, during its current term, the Court has decided one case regarding the degree to which racial considerations are permitted to impact how district lines are drawn and is considering another such case.
While racial gerrymandering claims have been a recent focus of litigation, the Supreme Court is also currently considering an appeal of a case involving partisan gerrymandering. In February 2017, a state appealed a three-judge federal district court ruling that invalidated a redistricting map as an unconstitutional partisan gerrymander. This case presents the Court with an opportunity to establish a standard for determining what constitutes unconstitutional partisan gerrymandering. While leaving open the possibility that such claims may be justiciable (that is, within the scope of judicial review), to date, the Supreme Court has yet not decided on a standard for assessing such claims.
Finally, a 2015 Supreme Court ruling held that the Elections Clause of the Constitution permits states to create nonpartisan independent redistricting commissions for congressional redistricting by ballot initiatives and referenda. If more states adopt similar laws, it could change the process of congressional redistricting nationwide.