Should Partisan Gerrymandering Be Allowed?

Last week, the Supreme Court began its new session and brought in the new session with a doozy of a case: Gill v. Whitford. This case is set to determine whether partisan gerrymandering is constitutional or not. Partisan gerrymandering is the practice of drawing [congressional] district lines in order to give one party an advantage over the other. The term comes from when Massachusetts governor Elbridge Gerry signed a redistricting bill in 1812 in a way where the district was shaped like a salamander, hence the portmanteau "gerrymander." Two main methods of gerrymandering are concentrating the opponent's voters into one district ("packing") or by spreading out the opponent's votes throughout multiple districts ("cracking"). In the case of Gill v. Whitford, the contention is that the Republicans in Wisconsin drew the district lines in such a way to provide the Republicans more seats in the state assembly than the Democrats.

The plaintiffs are arguing using a method calculating what is referred to as the "efficiency gap" (see more here for further details). The efficiency gap is calculated by taking the difference between "wasted votes" (i.e., votes beyond what are necessary to win an election) for each party and dividing that difference by the total number of votes. Anything beyond 7 percent would show that one party is getting a wasted-vote advantage, and would [based on their argument] be gaining undue advantage. The defendants are arguing that the efficiency gap not only fails to take in such traditional criteria as contiguity and compactness, but also that the redistricting ought to be challenged on a district-by-district basis. This Supreme Court case will be important because it will determine how congressional districts will be drawn in the future. The question is whether we have a case of politicians drawing district lines in such a way where politicians choose their constituents instead of constituents choosing their politicians.

As the Washington Post points out, 83 percent of the decline in swing districts between 1997 and 2017 was due to the political evolution of the American voter (i.e., it had nothing to do with redistricting). What this means is that the Republican's rise to power in 2010 did not have to do with gerrymandering. However, the solidification of the Republican hold in Congress is being maintained by gerrymandering. This, of course, is to insulate themselves from competition and insure their incumbency. This makes sense if the lines are drawn in their favor: it would become more expensive for a challenger to campaign in that district. Conversely, even in districts that are dominated by one party, there is still evidence of there being competitiveness within the primary election (Hirano and Snyder, 2014; Abramowitz et al., 2006). Furthermore, the effects of gerrymandering are exacerbated by the fact that voting is not based on issues or candidates like it used to be; it is based on parties.

There is also a question of how much it has polarized legislators. One can argue that gerrymandering has a negligible effect on Congressional polarization (McCarty et al., 2009), which would mean that the polarization is because of how Democrats and Republicans represent moderate districts. Even if the districts are drawn to be more heterogeneous and competitive, the impact on polarization would be minimal. Some, however, disagree about the polarization, and argue that gerrymandering causes more polarized politicians to be elected (Caughey et al., 2017). In terms of polarization, gerrymandering deviates the results away from broader statewide attitudes (Mattingly and Vaughn, 2014). And to think none of this gets into how gerrymandering makes creating third parties all the more difficult.

Additionally, I have to wonder how much of an advantage the parties have had as a result of gerrymandering. Historically speaking, fair districts have been the norm, not the exception. More to the point, there has been a roughly even balance of wasted votes from both parties (Stephanopolous and McGhee, 2014), which would mean that gerrymandering is not as bad as perceived. Other good news: gerrymandering does not increase the rate of incumbency (Friedman and Holden, 2009).

While gerrymandering is not the cause of all political woes, there are still enough problems where it needs to be reformed, regardless of the party that is doing the gerrymandering. Gerrymandering invites more overt corruption, especially when our governance should be representative of the people. The question is how does one reform the redistricting process. One facet that will make this Supreme Court case messier is that there are other measures of a gerrymander, which implies that there is no obvious system that gives people the optimal representation. The Supreme Court is going to have to sift through a question that is not just about politics, but also mathematics and cartography. The two main questions are who draws the lines and how they should be drawn. There ought to be such traditional criteria as being contiguous, compact, and congruent. There is the question of whether or not an independent commission is a good idea because of the mixed results (Henderson et al., 2017).

Ultimately, the Gill case has major ramifications. If the Supreme Court defines the "efficiency gap" as a principled and objective manner of drawing district lines, then Gill v. Whitford will change electoral politics for the foreseeable future.

11-13-2017 Addendum: The Cato Institute recently released an essay on why libertarians, and indeed everyone, should care about the implications of partisan gerrymandering.