The Most Exciting Attack On Partisan Gerrymandering In Over A Decade


America’s anti-gerrymandering law is an incoherent mess.

Thirty years ago, in Davis v. Bandemer, the Supreme Court held that a partisan gerrymander may be struck down as unconstitutional upon proof of “both intentional discrimination against an identifiable political group and an actual discriminatory effect on that group.” Yet the Court struggled to determine where to draw the line between lawful and unlawful maps.

Nearly two decades later, in Vieth v. Jubelirer, the justices seemed even more confused. Four of them called upon federal courts to simply give up on solving the problem of partisan gerrymanders. Four others splintered into a maze of dissenting opinions, altogether proposing a total of three different standards for weighing alleged gerrymanders. In the middle, Justice Anthony Kennedy threw up his hands in frustration. “The failings of the many proposed standards for measuring the burden a gerrymander imposes on representational rights make our intervention improper,” Kennedy wrote. Nevertheless, he concluded that “if workable standards do emerge to measure these burdens . . . courts should be prepared to order relief.”

Now, a dozen years after Kennedy despaired for want of a workable way to uncover partisan gerrymanders, two young scholars may have cracked the code. In a paper published in the University of Chicago Law Review last year, law professor Nicholas Stephanopoulos and political scientist Eric McGhee propose a mathematical formula judges can use to identify suspect maps. This formula is now the subject of a federal lawsuit, Whitford v. Nichol, which has survived two motions, submitted by defenders of Wisconsin’s Republican-drawn maps, that sought to kill the case. Moreover, because of a quirk of federal law, the case is overwhelmingly likely to wind up in the Supreme Court.

The “Efficiency Gap”

Stephanopoulos and McGhee’s central insight is that gerrymanders operate by forcing the disadvantaged party to “waste” votes. Some voters are shunted into districts where their party’s candidate has no chance of winning, a process known as “cracking.” Others are crammed into districts that so overwhelmingly favor their party’s candidate that casting an additional ballot for that candidate merely adds padding to a foregone conclusion, a process known as “packing.” “A gerrymander,” Stephanopoulos and McGhee write, “is simply a district plan that results in one party wasting many more votes than its adversary.”


To sniff out possibly gerrymanders, Stephanopoulos and McGhee begin by counting each party’s “wasted” votes. As the three-judge panel hearing the Whitford case explained in a recent opinion, a wasted vote occurs when a voter either casts a ballot “for a candidate who lost the election” (suggesting that the voter was targeted by cracking), or if they cast a ballot “for the winning candidate, but in excess of what the candidate needed to win” (suggesting that the voter was packed).

As Stephanopoulos and McGhee note, some number of wasted votes are inevitable in elections involving single-member districts. But a fair map should produce roughly equal numbers of wasted votes for both parties. To determine which maps diverge too far from the ideal, the two scholars offer a metric they call the “efficiency gap,” which is calculated by taking the difference of the two parties’ wasted votes and then dividing it by the total number of votes cast. The plaintiffs in Whitford (speaking through a team of lawyers that includes Stephanopoulos) offer an example of how to calculate this figure in their complaint:

Suppose, for example, that there are five districts in a plan with 100 voters each. Suppose also that Party A wins three of the districts by a margin of 60 votes to 40, and that Party B wins two of them by a margin of 80 votes to 20. Then Party A wastes 10 votes in each of the three districts it wins and 20 votes in each of the two districts it loses, adding up to 70 wasted votes. Likewise, Party B wastes 30 votes in each of the two districts it wins and 40 votes in each of the three districts it loses, adding up to 180 wasted votes. The difference between the parties’ respective wasted votes is 110, which, when divided by 500 total votes, yields an efficiency gap of 22% in favor of Party A.

An efficiency gap of more than 7 percent, these plaintiffs claim, is indicative of a partisan gerrymander. When combined with evidence that the state acted intentionally to give one party an advantage, they argue that courts should presume that a map that produces such a high efficiency gap is an unconstitutional partisan gerrymander.

What This Solves

The genius of this “efficiency gap” is twofold. First off, it offers what Justice Kennedy described as a “workable standard” — an objective test that can be used by judges across the country to sort suspect maps from permissible ones. A hundred different judges can examine the same maps and, provided that they are all skilled at arithmetic, all reach identical conclusions about which maps fall within an acceptable range and which ones should be presumed to be unconstitutional.


The second advantage of Stephanopoulos and McGhee’s method is somewhat counterintuitive, but may be necessary to swing Kennedy’s vote. “[T]here is no constitutional requirement of proportional representation,” the justice wrote in League of United Latin American Citizens v. Perry, suggesting that he may reject a formula that seems to command states to draw maps that will guarantee that a party with 55 percent of the vote will win 55 percent of the legislative seats. In a phone conversation with ThinkProgress, Stephanopoulos also expressed concern that a legal standard that placed proportional representation on a platform would not fare well in court.

Wisconsin Republicans “hired a law firm and a political scientist to design an Assembly plan that would maximize the electoral advantage of Republicans.”

Indeed, when a party gains one percent of the vote share in a given state, they typically receive more than one percent more representation in the state legislature — a phenomenon Stephanopoulos described as a “winner’s bonus.”

To understand why this winner’s bonus exists, imagine a hypothetical state with 1,000 voters all divided evenly into ten districts. Imagine as well that each district is evenly split between the two major parties — thus they each contain 50 Democrats and 50 Republicans. Now imagine that ten additional voters, all Republicans, move to this state. Each district where at least one of the new voters decides to make a home will become a Republican district, and if the ten voters evenly distribute themselves throughout the state, every district in the state will become a Republican district, even though the GOP’s overall advantage in the state’s total population is minuscule.

Of course, real elections are rarely this simple or this stark, but the point is that small shifts in a state’s partisan preferences can potentially have disproportionate impacts on who the state elects. Stephanopoulos and McGhee’s method implies that the appropriate size of the winner’s bonus should be that “each additional percentage point of vote share for a party should result in an extra two percentage points of seat share.”

But Can It Win?

The test offered by the plaintiffs in Whitford, which is based on Stephanopoulos and McGhee’s scholarship, is not a perfect solution to the problem of gerrymandering. For one thing, it effectively gives lawmakers a free election where they can enact gerrymandered maps and not need to worry that a court will strike them down in advance of the election. This is because the only way to calculate a map’s efficiency gap is to first run an election under that map and then add up the wasted votes.


Additionally, it may not catch the most devious gerrymanders. In a nod to Davis’ holding that plaintiffs must show “both intentional discrimination against an identifiable political group and an actual discriminatory effect on that group” in order to prevail in a gerrymandering case, the Whitford plaintiffs explain that a high efficiency gap is not enough to prove gerrymandering, or even to establish a reputable presumption that a map is gerrymandered. Rather, to win their case, plaintiffs challenging a gerrymander must also show that the mapmakers acted with discriminatory intent when they drew the maps.

That’s probably not going to be a high bar to clear in Whitford where it is uncontested that Wisconsin Republicans “hired a law firm and a political scientist to design an Assembly plan that would maximize the electoral advantage of Republicans.” In other cases, however, lawmakers may learn to do a better job of covering their tracks.

Whatever its flaws, however, the plaintiffs’ proposed standard in Whitford does have one important virtue: it may have a better likelihood of prevailing in court than any other standard previously proposed by litigators. In federal litigation, defendants typically can make multiple attempts to convince a court to kill a case before it goes to a full trial. Whitford has now survived two of the most potent weapons in the Wisconsin defendants’ arsenal — a motion to dismiss and a motion for summary judgment. Significantly, they’ve done so despite the fact that the three-judge panel hearing this case includes a Reagan appointee and a George W. Bush appointee (the third judge was appointed by President Jimmy Carter).

The fact that two Republican appointees believe that Whitford deserves a full trial suggests that some conservative justices, like Kennedy, might be convinced that Stephanopoulos and McGhee have found the solution to the problem of partisan gerrymandering. Moreover, though the Supreme Court normally has discretion to turn away cases it does not want to hear, it has far less ability to ignore cases heard by three-judge district courts. So even if Kennedy (or, for that matter, a newly constituted Court that could soon include Supreme Court nominee Merrick Garland) would prefer not to wade into the fraught waters of partisan gerrymandering, it is far from clear that he’ll be able to avoid doing so.

Should the Whitford plaintiffs prevail, moreover, they could completely upend the results of the next several elections. Currently, many states’ maps are so severely gerrymandered that the winners and losers in many districts are predetermined. Consider six swing states where Obama prevailed in 2012, but where Republicans captured commanding majorities in the state’s U.S. House delegation at least in part due to gerrymandering:

If these maps remain in place, it is not literally impossible for Democrats to win a majority in the House, but it sure won’t be easy. Whitford, in other words, could potentially restore a world where both parties have a fair shot to capture majorities in Congress and, with that, gain the power to actually pass legislation.