Do Redistricting Commissions Avoid Partisan Gerrymanders?

As attempts to combat partisan gerrymandering transition from proposals to the Supreme Court to state-based districting commissions, it is time to ask two questions. First, how well did commissions in the 2010 round of redistricting perform as neutral decision makers? We answer that question with applications to each of the three independent commissions (AZ, CA, and WA) and four other commission forms (IA, NJ, NY, and VA) in place for post-2010. We take as the neutrality criterion the idea that a commission would produce a district plan that comports with a partisan outcome that could be expected from a set of approximately 10,000 computer generated plans adhering to minimalist constraints of contiguity, compactness, and equal populations. Our results indicate three of seven commissions produced suspect results that redounded to the benefit of one party or the other: pro- Democrat in Arizona; pro-Republican in New Jersey and Virginia.