CRS – Congressional Redistricting Law: Background and Recent Court Rulings, March 23, 2017. [via FAS]

“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 district..”