The NCSL Blog


By Wendy Underhill

A federal court has ruled unanimously that Wisconsin can't wait until its redistricting case is heard by the Supreme Court to redraw the state's legislative maps because they were too partisan in favor of Republicans.

Assembly Speaker Pro Tempore Tyler August (left), Assembly Speaker Robin Vos (center) and Senate President Roger Roth (right) applaud Gov. Scott Walker as he delivers his state of the state address during a joint session of the state Legislature in January in Madison.(Photo: Rick Wood / Milwaukee Journal Sentinel)The panel ruled unanimously that Governor Scott Walker and the legislature must redraw the districts by Nov. 1 to ensure their use in the fall 2018 elections.

When the initial decision against the state came down in November, we listed three things to know about Whitford v. Gill (formerly Whitford v. Nichol):

First, this decision marks the end of one stage in what is likely to be a lengthy legal contest. The results will be appealed, says the state’s attorney general. Observers say the case is likely to reach the U.S. Supreme Court.  “It’s unprecedented and it isn’t over,” said Wisconsin’s House Speaker Robin Vos.

Second, the case is based on allegations of partisan line-drawing, something that Democratic and Republican majorities are equally likely to do. To date, there has been no legal standard to stop plans that allocate voters among districts for political purposes, although the courts have left the door open for a case that might set a standard. Indeed, partisanship is not addressed in traditional redistricting principles. Rather, most redistricting cases are based on claims of racial discrimination, differences in district populations, or procedural missteps.

Third, the case offered the courts a new standard: A statistical measure to gauge partisanship called “the efficiency gap.” The concept comes from University of Chicago law professor Nicholas Stephanopoulos, as described in “Partisan Gerrymandering and the Efficiency Gap.” 

The efficiency gap formula calculates how many votes each party “wastes” compared to each other. (A wasted vote is any vote on the winning side that is above 50 percent plus one, or any vote that’s cast on the losing side.) 

The idea is that if voters of the minority party, whether Ds or Rs, are either “packed” too tightly into certain districts during redistricting, or spread too thinly in other districts, then the redistricting plan doesn’t treat the parties evenhandedly. And that’s the legal question addressed in Whitford.

Wendy Underhill heads NCSL’s Elections and Redistricting Program.

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This blog offers updates on the National Conference of State Legislatures' research and training, the latest on federalism and the state legislative institution, and posts about state legislators and legislative staff. The blog is edited by NCSL staff and written primarily by NCSL's experts on public policy and the state legislative institution.