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5 Things to Know About the Wisconsin Partisan Gerrymandering Case

With Gill v. Whitford, the U.S. Supreme Court has taken the most important case in decades dealing with how Americans are represented in Congress and state legislatures.

In the next few weeks, the Supreme Court will be consid­er­ing whether to hear Gill v. Whit­ford, a major partisan gerry­man­der­ing case out of Wiscon­sin. Here’s what you need to know.

1.  What’s Gill v. Whit­ford about?

Wiscon­sin is asking the Supreme Court to over­turn a decision strik­ing down the 2011 redis­trict­ing plan for the lower house of the Wiscon­sin state assembly as a partisan gerry­mander.

The Wiscon­sin voters who brought the case chal­lenged the plan under the First and Four­teenth Amend­ments of the U.S. Consti­tu­tion and, in late 2016, won at trial — the first time in over three decades that a map has been struck down as a partisan gerry­mander. The lower court ruled that the plan was “an aggress­ive partisan gerry­mander” that locked in a Repub­lican major­ity in the state assembly under “any likely elect­oral scen­ario.”

If the Supreme Court agrees to hear the case (it would be argued this fall), it will be the first time the high court has considered the consti­tu­tion­al­ity of partisan gerry­man­der­ing in more than a decade. The case could have major implic­a­tions for redis­trict­ing because, thus far, the Supreme Court has not been able to agree on a stand­ard for decid­ing when a map goes too far. The Wiscon­sin case could at last give it that oppor­tun­ity.

2.  What makes the gerry­mander in Wiscon­sin espe­cially bad?

Gerry­man­der­ing comes in many vari­et­ies, but the kind of gerry­man­der­ing that took place this decade in Wiscon­sin (and a hand­ful of other states) is among the worst. This kind of aggress­ive gerry­man­der­ing does­n’t just pre-determ­ine elect­oral results, but also locks in a dispro­por­tion­ate and unfair advant­age for one party over the other — making maps unre­spons­ive to voters in indi­vidual districts and deeply unrep­res­ent­at­ive of the elect­or­ate as a whole.

At a statewide level, Wiscon­sin is a quint­es­sen­tial battle­ground where races are often decided by only a few percent­age points. Contrast that to the state assembly map the Repub­lic­ans drew: In 2012, they won 60 of the 99 seats in the Wiscon­sin Assembly despite winning only 48.6% of the two-party state-wide vote; in 2014, they won 63 seats with only 52% of the state-wide vote.

This is an odd outcome for a state like Wiscon­sin, where statewide elec­tions are very close, and voters for both major parties are fairly evenly spread across the state. Voters in Wiscon­sin, like voters in battle­ground states in general, are not starkly clustered by party. For example, there are substan­tial pock­ets of Demo­cratic voters in places like Vernon County and other rural and small towns, where Donald Trump and Hillary Clin­ton nearly evenly split the vote. The fact that Wiscon­sin’s Legis­lature does­n’t reflect this polit­ical diversity is, in large part, inten­tional.

The same sort of aggress­ive gerry­man­der­ing has distor­ted the U.S. Congress as well. Accord­ing to a Bren­nan Center study, these “extreme maps” account for 16 to 17 Repub­lican seats in the current Congress, a sizable portion of the 24 seats Demo­crats would need to take back the House.

3.  Why is it urgent that the Supreme Court take action against partisan gerry­man­der­ing now?

Amer­ic­ans across the polit­ical spec­trum agree by wide margins that gerry­man­der­ing is bad. In 2013, a Harris poll found that seven in ten Amer­ic­ans agreed that those who stand to bene­fit from draw­ing elect­oral lines should not have a say in the way those lines are drawn. This view cut across partisan lines, with 74 percent of Repub­lic­ans, 73 percent of Demo­crats, and 71 percent of inde­pend­ents in agree­ment. Even elec­ted offi­cials agree. Ohio governor John Kasich recently called gerry­man­der­ing “the biggest prob­lem we have.” Like­wise, Pres­id­ent Obama called for an end to gerry­man­der­ing in his final State of the Union address in 2016, echo­ing calls made by Pres­id­ent Reagan thirty years earlier.

Unfor­tu­nately, gerry­man­der­ing is only going to get worse, as legis­lat­ors and consult­ants gain access to even more power­ful mapping tech­no­logy and more soph­ist­ic­ated data about voters to make gerry­manders that are even more biased and even more durably so. The same sort of “Big Data” that gives retail­ers and polit­ical campaigns greater insight into people’s beha­vior will increas­ingly be used in redis­trict­ing as well.

Gerry­man­der­ing is one prob­lem voters can’t fix on their own. Citizens can’t just vote the gerry­man­der­ing party out of office, because the maps are too heav­ily skewed. In fact, that’s the whole point of extreme partisan gerry­manders: to insu­late the legis­lat­ive major­ity from the will of the voters. And while 24 states provide for some form of ballot initi­at­ive that could be used to push redis­trict­ing reforms, many other states don’t make this option avail­able to voters.

A ruling from the Supreme Court declar­ing that partisan gerry­man­der­ing is uncon­sti­tu­tional will, at the very least, create some limits that legis­lat­ors will have to obey when they draw maps in the future.

4.  How can a court tell when partisan gerry­man­der­ing has gone too far?

Deeply rooted consti­tu­tional values that ensure repres­ent­a­tion and demo­cratic account­ab­il­ity make clear that extreme gerry­manders are illegal.

There are several types of evid­ence that can help trial judges tell when these values have been viol­ated. For instance, in Wiscon­sin, the trial court was able to consult, among other things, emails and docu­ments that showed how the Legis­lature’s consult­ants used advanced stat­ist­ics to eval­u­ate how partic­u­lar districts they drew would vote and then figure out which maps would advant­age Repub­lic­ans the most. Also in evid­ence was a string of altern­at­ive maps that grew increas­ingly biased and notes from people involved in the redis­trict­ing process record­ing their under­stand­ing of the long-term effects of the maps they chose to use. Addi­tion­ally, Courts can look at the features of a state’s mapping process and polit­ical climate. For example, when a single party controls the redis­trict­ing process, it has a unique oppor­tun­ity to create extreme maps.

The courts will also have the bene­fit of evid­ence in the form of social science meas­ures that schol­ars have developed over the last decade to help them identify when maps have signi­fic­ant, inten­tional bias. The good news is that although these tests approach the issue in slightly differ­ent ways they all flag the same hand­ful of prob­lem state. The task for the Supreme Court won’t be to decide which of these tests courts must use. Trial courts can and should weigh a broad vari­ety of evid­ence as they do in all kinds of cases, and make judg­ments about the value of expert evid­ence as they do in many settings.

5.  How many other maps could be affected by a ruling in the Wiscon­sin case?

A ruling for the plaintiffs in the Wiscon­sin case would put in place an import­ant limit­a­tion ahead of the next round of redis­trict­ing in 2021.

In the short-term, it could set the stage for chal­lenges to around half a dozen congres­sional maps that exhibit extreme partisan bias. 


Research by Univer­sity of Sydney professor Simon Jack­man, like­wise, suggests that legis­lat­ive maps in under a dozen states could be suscept­ible to chal­lenge for extreme partisan bias. 


It’s prob­ably not surpris­ing that, with a couple of excep­tions, the states with the worst bias were ones where a single party controlled all the levers in the redis­trict­ing process, though Flor­id­a’s maps were redrawn in 2016 under court super­vi­sion to sharply reduce bias. Excep­tions are New York and Virginia, where the party being adversely affected had the power to block adop­tion of the biased map but did not do so.

By contrast, maps drawn by commis­sions, courts, and, with a couple of excep­tions, split control legis­latures did not exhibit stat­ist­ic­ally signi­fic­ant partisan bias.