Wisconsin Republicans gained control of the state legislature and the governor's office in 2010 for the first time in 40 years and then set about drawing up legislative districts to secure a Republican majority for the rest of the decade. As the legislature was about to act, an aide to the Senate's Republican leader told the GOP caucus they had "an opportunity and an obligation to draw these maps that Republicans haven’t had in decades."
The legislative districts have now been found by a federal court to have been designed to benefit Republicans and to have had that intended effect. That much is obvious from election statistics. Republicans drew 48.6 percent of the votes cast for Assembly candidates in 2012 but won 60 of the chamber's 99 seats. Two years later, Republicans won 63 Assembly seats with 52 percent of the statewide vote.
Democratic voters challenging the redistricting have now won a split ruling from a three-judge federal district court that the redistricting amounts to an unconstitutional political gerrymander. The new map was "intended to burden the representational rights of Democratic voters throughout the decennial period by impeding their ability to translate their votes into legislative seats," Judge Kenneth Ripple wrote for the court.
Both the plaintiffs and the court faced the difficulty that up till now the Supreme Court has failed to find a basis to decide when partisan gerrymandering goes too far. In three decisions over the span of 20 years, the court has recognized constitutional claims against political gerrymandering but upheld each of the challenged plans for lack of any agreed-on standard to apply.
To remedy that gap, the plaintiffs secured the services of an experienced election law litigator now at the University of Chicago Law School. Nicholas Stephanopoulos, just granted tenure at Chicago after several years previously at the Washington law firm Jenner & Block, believes that he and an academic colleague have found the silver bullet needed to establish a legal limit on partisan manipulation in redistricting.
The answer proposed in a law journal article by Stephanopoulos and his coauthor, the California political scientist Eric McGhee, is appealingly straightforward. They created a quantifiable datum they call it the "efficiency gap" to compare how efficiently the respective political parties use their voters to win legislative seats.
In brief, think of the winning party's margin of victory in any district beyond a one-vote plurality as "wasted" votes -- more than needed to win the seat. Votes cast for a losing candidate are wasted by the other party. Add up all the wasted votes either "surplus" votes or "lost" votes for each party, calculate the difference, and divide by the total number of votes cast. A low figure, say 2 percent, indicates a district map of relative partisan fairness, but Stephanopoulos and McGhee argue that a figure above some threshold they suggest 8 percent goes too far and ought to be deemed unfair enough for a court to rule the redistricting plan presumptively invalid. Based on this measure, they say partisan gerrymandering is worse now than ever in the elections they studied.
Stephanopoulos and McGhee argued that their test was better than what has been called the "partisan symmetry" test. Under that approach, a redistricting plan survives challenge as a partisan gerrymander politically if each party would win the same number of legislative seats for a particular vote percentage as the other party would win if it had received the same percentage of the vote.
Five justices indicated support for this approach in the most recent decision, Latin American League of United Citizens v. Perry (2006), but in the main opinion Justice Anthony M. Kennedy said the plaintiffs had offered no way to measure how much asymmetry was too much. Stephanopoulos and McGhee say their approach has the advantage of using actual election data instead of a hypothetical election and they go one step further by suggesting a threshold to define how much is too much.
The majority judges in the Wisconsin case were convinced that the 11.69 percent efficiency gap was too much. Lawyers for the state argued that the Republicans' advantage stemmed from political geography: Democrats are concentrated in urban areas so more "surplus votes" while Republicans are dispersed more widely in suburban and rural areas. In his opinion, Ripple, a senior circuit judge appointed by President Ronald Reagan in 1985, acknowledged the point but said it gave Republicans only "a modest advantage," not the lopsided edge they achieved with the maps being challenged.
The two other judges split along partisan lines. Barbara Crabb, a senior judge named by President Jimmy Carter in 1979, joined Ripple's opinion, while William Griesbach, named by President George W. Bush in 2002, dissented. In his dissent, Griesbach argued that the efficiency gap "oversimplifies political injury," but he appeared to offer no alternate approach.
Stephanopoulos got the unusual opportunity for a professor to put his academic theory into practice after a fellow election law scholar referred him to the Wisconsin plaintiffs to represent them. The state plans to appeal the ruling to the Supreme Court. Stephanopoulos welcomes the chance. The case, he says, would give the Supreme Court "a golden opportunity to put a stop to one of the most pernicious and undemocratic practices in American politics today." As always, court watchers will be watching Kennedy, but the case is unlikely to reach the justices before next fall.