Redistricting Criteria, Standards, and Requirements
The following points are a general description of commonly accepted legal principles that have been developed over the years to govern redistricting. When redistricting, what is or is not permissible under the state and federal constitutions and the Voting Rights Act often depends on a variety of factors that are unique to any given situation.
Congressional Districts: The reapportionment of congressional districts (which are drawn and established by the General Assembly, not the Board of Apportionment) must as nearly as practicable result in each congressional district having an equal population so that one citizen’s vote in a congressional election is worth the same as another citizen’s vote. See, e.g., Westbury v. Sanders, 376 U.S. 1, 84 S.Ct. 526 (1964).
State Legislative Districts: A slightly less stringent standard applies to the redrawing of state legislative districts under the Equal Protection Clause of the Fourteenth Amendment to the United States Constitution. The primary state legislative redistricting standard for the Board of Apportionment is “substantially equal population” in respective senatorial and house districts. In a 1964 case, the U.S. Supreme Court stated that “the overriding objective must be substantial equality of population among the various districts, so that the vote of any citizen is approximately equal in weight to that of any other citizen in the State." Reynolds v. Sims, 377 U.S. 533, 579, 84 S.Ct. 1362, 1390 (1964). States may deviate from absolute perfect equality due to such considerations as are set forth below.
History: From the 1960s until the early 2000s, the U.S. Supreme Court developed an allowable deviation in state legislative redistricting called “The 10% Rule.” In a series of cases following the Reynolds case, the Supreme Court established a 10% presumption of constitutionality for state legislative redistricting. If a state drew all of its districts within 10% of each other in population, then the courts would generally presume that the state’s district map passed muster under the one-person, one-vote standard. If the variance exceeded 10%, then the state would have to prove some extraordinary circumstances justifying the deviation. Thus, there is a presumption that if a state’s largest and smallest districts are more than 10% apart, the redistricting plan is not constitutional. However, meeting the 10% target is not necessarily sufficient—for example, districts may be found to have been drawn unconstitutionally if there is evidence of wrongful intent, even when the difference is less than 10%. Examples of wrongful intent include discrimination based on race or ethnicity, attempting to protect or disadvantage an incumbent, bribery, or attempting to minimize the voting impact of one community of interest at the expense of another.
Compliance with the Voting Rights Act of 1965 (VRA): In addition to equal population as the primary goal and the Fourteenth Amendment’s prohibition against intentional discrimination, the VRA prohibits any practice or procedure that has a discriminatory effect on racial or language minorities. A common example of a discriminatory practice or procedure would be districts that are drawn, intentionally or not, so that minorities do not have an equal opportunity to elect a candidate of their choice. A de facto exception to the prohibition against drawing legislative districts based on race is the VRA and case law that require districts to be drawn to allow minority populations to elect candidates of their choice. The courts have recognized that the Census data will show where there are concentrations of minorities, but this is not to be used as a primary consideration. In order to comply with the directive not to base redistricting on race, after districts are drawn, demographic data including racial and language minority population concentrations are overlaid on the district map, and adjustments to boundaries may be made and the reasons documented.
Compliance with the Equal Protection Clause of the Fourteenth Amendment: Courts have held that the Equal Protection Clause of the Fourteenth Amendment means that mapmakers cannot draw districts based solely or primarily on race. The U.S. Supreme Court has held that districts should not be defined exclusively by race, although it is permissible to take race into account while drawing district boundaries. There are exceptions for drawing or adjusting a district based on racial considerations in order to avoid a violation of the Voting Rights Act.
Geographically Contiguous Districts: Generally, districts must be geographically contiguous. The entire district must be substantially connected. For example, it would not be permissible to have a portion of a district as an “island” that was not connected geographically to the rest of the district.
Geographically Compact Districts: Ideal districts are also geographically compact. In practice, most districts have some irregularity in shape; nevertheless, the more bizarre the district shape, the less likely it is to be approved by the courts. There are many measures of compactness, but generally, smooth boundaries and the closeness of a district’s boundaries to a common core are good indicators of a compact district.
Minimizing Splitting Political Subdivisions: Courts have held that it is preferable to minimize splitting political subdivisions such as counties, cities, and voting precincts. When possible, it is better to keep whole counties, cities or towns, wards, and so forth intact. Districts must still comply with the requirements of the VRA, however, and there can be complications when anomalies occur, for instance, where municipal boundaries cross county boundaries.
Maintaining Cores of Existing Districts Where Practicable: Preservation of the “cores,” including the general locations and shapes of existing districts is a common redistricting principle. When district lines are redrawn, mapmakers can take into account existing districts, their geographic locations, and their current populations. This helps preserve continuity of representation.
Avoiding Pairing Incumbents: It is permissible to try to avoid making current officeholders run against other incumbents by not drawing a new district that includes two or more incumbents. The rationale for this principle is that voters who have already chosen a candidate should be able to continue to choose that same candidate if desired. However, it is also possible that two incumbents might be placed in the same district if necessary to meet other requirements of equal representation. For example, when there are large population losses, existing districts must expand and incumbents may unavoidably be placed in the same district. When there are large population gains, additional districts will be added into an area, and again incumbents may unavoidably be placed in the same district.
Maintaining Communities of Interest Where Possible: Preservation of communities of interest describes the goal of maintaining a substantial group of people in a specific geographic area where those individuals share common identifiable interests. Those interests may be economic, social, cultural, residential (rural vs. urban), ethnic, military, religious, or political in nature. As an example, a redistricting plan may consider keeping all of a military base in one district.