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Report · March 2018

Assessing California’s Redistricting Commission: Effects on Partisan Fairness and Competitiveness

Eric McGhee

The creation of the Citizen Redistricting Commission (CRC) in 2008 was a radical departure from California’s previous redistricting process, which had been directed by the legislature with little public input and no official rationale. Many hoped that, in addition to meeting legally mandated representational and geographic goals, the CRC would produce electoral maps that were fair to the two major parties and more competitive than the maps that had been drawn by the legislature.

This report evaluates election outcomes under the CRC plan using two new measures of partisan gerrymandering, as well as established metrics of competitiveness. It also compares these outcomes to results under the previous plan and places them in a national context. The analysis leads to the following conclusions:

  • The CRC largely satisfied expectations that it would produce plans that are fair to each major party and that increase electoral competitiveness.
  • While Democrats have a greater advantage under the CRC plans than they did under the plans drawn by the legislature, this advantage is very small. For the state legislature, the advantage falls within the nationwide range. For Congress, the advantage is by some measures at the high end of Democratic advantage nationwide.
  • The size and direction of the advantage under the CRC plan varies over time. The typical election year has featured a small advantage under both the CRC and legislative plans.
  • The CRC maps are somewhat more competitive than the maps drawn by the legislature. Competitiveness under the CRC state legislative plan remains low compared to plans in other states, while the CRC congressional plan is one of the most competitive in the country.
  • Evidence of greater competitiveness is consistent over time. Every year under the CRC maps has been more competitive than all but one year under the legislative maps.
  • Overall, the CRC plans have moved California in the opposite direction from the rest of the country: other state plans are on average more favorable to Republicans and less competitive than plans from the last round of redistricting.

The report concludes that future CRCs should use partisan data to help them produce competitive and fair maps. If they do, they should identify measures and standards for using this information before holding hearings or drawing district lines. Moreover, the CRC should use measures that are appropriate for states like California, in which one party (the Democrats) holds a clear statewide majority. There are also sophisticated methods for automatically drawing redistricting plans that could prove useful to the CRC in future drawing efforts.

This is an especially good time to consider the partisan consequences of the commission’s work. The independent commission model is still rare, but many states have considered or are considering adopting something like it-particularly in light of two US Supreme Court cases, Gill v. Whitford and Benisek v. Lamone, which could establish a new legal standard for partisan gerrymandering. For California and for other states considering redistricting reform, fairness and competitiveness should be important aims.


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