On Tuesday, the Supreme Court will hear an appeal of a lower court ruling that struck down Wisconsin’s Republican-drawn state Assembly map as an unconstitutional partisan gerrymander. Over the past three decades, the high court has repeatedly held that partisan gerrymandering could in theory run afoul of the Constitution, but it has never struck down any maps on these grounds because it’s never been able to decide upon a standard for when to do so. If, however, the Supreme Court changes course and sides with the district court, a ruling in Gill v. Whitford could establish a sweeping precedent leading to a slew of lawsuits against partisan gerrymanders nationwide.
Republicans aggressively gerrymandered Wisconsin after they gained full control of the state’s government following the 2010 GOP wave. Their Assembly lines were particularly effective: Republicans won a commanding 60-to-39 majority in the chamber in 2012 even as Barack Obama carried Wisconsin by 7 percentage points and Democratic legislative candidates won more votes statewide than Republicans did by a similar margin. And as shown in the map at the top of this post, Republicans maintained a lopsided 64-35 majority in 2016, despite the fact that Donald Trump won the state by less than one percent of the vote.
While it has regularly invalidated maps for improperly using race, the Supreme Court, as noted above, has never struck down a map for excessive partisanship despite 31 years of precedent that partisan gerrymandering could theoretically be unconstitutional. In a 2004 case on this topic called Vieth v. Jubelirer, Justice Anthony Kennedy, as the deciding vote, refused to strike down the map at issue on the grounds that it represented an unfair partisan gerrymander. However, Kennedy effectively opened the door for future challengers if they could ever come up with a new standard for evaluating such claims—a standard that would have to satisfy the court’s perennial swing justice.
The plaintiffs in Wisconsin have sought to overcome this problem by proposing a mathematical test called the “efficiency gap” that examines how many votes get “wasted” in each election, which we have explained in detail here. Under this test, if one party routinely wins landslide victories in a minority of seats while the other party wins much more modest yet secure margins in the vast majority of districts, that could signify a gerrymander that has gone so far as to infringe upon the rights of voters to free speech and equal protection. Although this test has some major flaws, it provides one of many tools a court could use to judge a map’s partisan distortion.
And that’s exactly what the lower court here did: Late last year, a federal district court struck down the GOP’s map for the Wisconsin Assembly for excessive partisanship. The judges acknowledged the efficiency gap, though they did not rely on it as a silver bullet. Instead, the court laid out a three-part test to determine if a mapmakers have engaged in partisan gerrymandering: whether there’s (1) a durable partisan effect; (2) an intention by mapmakers to seek a partisan edge; and (3) a partisan lean that isn’t merely the result of mapmakers adhering to traditional redistricting criteria (such as district compactness), which the Constitution permits.
However, even if the Supreme Court agrees with the district court, the same Republican legislators who benefit from the existing gerrymander would get to draft a replacement map, though they wouldn’t be able to draw lines that are as brazenly partisan as the current districts are. Most problematically, plaintiffs under this framework have to prove after the fact that a gerrymander indeed punished the disfavored party, giving legislators license to draw partisan gerrymanders for two or more election cycles each decade.
Some of these statistical tests would still allow states to modestly gerrymander like they’ve done in Nebraska, just not to the current extremes they have gone to in states like Wisconsin. That's still a big problem because, just as with racial discrimination, any partisan discrimination should be too much. Even success in Whitford would still necessitate more substantial redistricting reforms, like ballot measures to create independent redistricting commissions.
Notably, the Supreme Court also stayed the lower court’s order for Wisconsin to redraw its districts in 2017 pending the GOP’s appeal, making it less likely that redistricting will take place in time to affect the 2018 midterm elections even if the plaintiffs prevail. Several observers have argued that the fact that the Supreme Court granted the stay suggests that plaintiffs will have a hard time succeeding on the merits of their case.
Kennedy siding with the plaintiffs appears to be less likely than not based on his history in Vieth, but as is so often the case with litigation, nothing is a foregone conclusion. Furthermore, if Trump appoints a replacement for 81-year-old Kennedy in the future, the court would likely have a majority of five ultra-conservatives who would take judicial policing of partisan gerrymandering off the table. Whitford could be the last chance at judicial action for years to come. And if plaintiffs do succeed, Whitford could indeed open up the floodgates for successful lawsuits against partisan gerrymanders across the country.
That tide of litigation would have enormous consequences, because Republicans have gerrymandered most congressional and legislative districts across America after the 2010 census. (Democrats only had the chance to do so in a tiny handful of states.) A victory for plaintiffs in Wisconsin could subsequently deprive Republicans of the lock that they have on Congress and legislatures across the country. On the other hand, a defeat could give (mostly Republican) mapmakers license engage in extreme gerrymandering for years to come.
While Whitford currently concerns just the Wisconsin Assembly map, future potential lawsuits could take years to resolve. Consequently a landmark ruling against partisan gerrymandering would most likely have its biggest impact after the 2020 census. Nevertheless, its outcome would immediately affect other key challenges to partisan gerrymanders that are working their way through the judicial system right now and could appear before the Supreme Court soon.