Do restricting reforms work? We investigate the effects of rules reforms and procedural reforms on districting outcomes. First, we investigate the effects of common “fair districting” criteria – that is, rules that require (or prohibit) certain outcomes in districting. We find little evidence that adding additional criteria will prevent partisan bias in districting. In many cases, such as district compactness requirements, it appears that districting authorities frequently ignore the rules. The biggest drawback with rules-based reforms is that they depend upon the judiciary for enforcement. We then evaluate the effects of “procedural reforms,” like citizen redistricting commissions. We find systemically less bias in districting when the maps are drawn by citizens and other independent bodies. Although the design and mechanics of commissions vary widely, we find the least bias in the maps drawn by redistricting bodies that forbid membership by politicians. This suggests that independent redistricting commissions represent an effective solution against partisan gerrymandering, provided they are staffed by citizens or independent public officials.

What lessons can we draw from the study of 2011 state legislative redistricting? We find that, on the one hand, predicting partisan gerrymandering is relatively simple: gerrymandering occurs when one party can monopolize redistricting and has an incentive to draw biased maps. One the other hand, our investigations of racial segregation and political geography reveal the intimate links between racial gerrymandering and political gerrymandering and suggest that the Republican Party in 2011 was willing to use racial vote dilution in many states in order to achieve extreme bias. We conclude with an assessment of redistricting reforms in Virginia and “best practices” in preventing partisan gerrymandering.

Although scholars have investigated the effects of redistricting for many decades, surprisingly little is known about the causes of redistricting outcomes. We argue that studying state legislative redistricting in 2011 provides a unique opportunity to identify the theoretical determinants of partisan gerrymandering and assess the political, social, and democratic consequences of bias. We also argue that the story of 2011 redistricting is incomplete without a comprehensive investigation of the causes and consequences of redistricting of state legislatures. Ultimately, our findings reveal the interconnectedness of racial and political gerrymandering and suggest that partisan bias has long-term consequences for public policy and democratic health, yet they also show that it is possible to design redistricting institutions to prevent bias.

Since the 1960s, the judiciary has become a key player in redistricting, and litigation has become an increasingly common feature of the decennial redistricting process. How do the courts fare when they draw the lines? We investigate the effects of court intervention in several states where federal and state courts redrew or forced changes to state legislative maps. We find that courts are only a partial solution to the problem of gerrymandering, because judicial actors are minimalistic in their treatment of redistricting and, as incrementalists, have a tendency to avoid extreme change. While the federal courts have been assertive in combatting racial gerrymandering, state courts have had only limited effect on partisan bias when they have been delegated the task of redistricting.