The proposal is surprisingly simple for such an arcane subject: Start by adding up each party’s “wasted” votes that don’t help them win a district. (If Party A wins 90 votes out of 100, 39 of its votes are wasted, since it only needs 51 for a majority. All 10 of Party B’s votes are also wasted in this scenario.) The difference between each party’s wasted votes, divided by the total number of votes cast, is the “efficiency gap.”
Across the Wisconsin State Assembly, Stephanopoulos and McGhee found a 13-percent efficiency gap in 2012 and 10-percent gap in 2014, both favoring Republicans. That translates to Republicans winning 13 percent more seats in 2012 and 10 percent more in 2014 than they would have under a map that treated members of both parties equally.
In Whitford, the plaintiffs use the efficiency gap to illustrate how steeply disadvantaged Democrats are in the state. But because Whitford is the first time that any plaintiffs have proposed this kind of test to measure the extremity of gerrymandering, the lawsuit’s repercussions could extend far beyond Wisconsin.
“A sweeping, nationwide Supreme Court victory is sort of the dream scenario,” said Stephanopoulos, who is also one of the lawyers working for the plaintiffs.
He added that he would also welcome a decision that only strikes down Wisconsin’s Assembly map, which would create a guideline for future lawsuits elsewhere. But Stephanopoulos expects the defendants to appeal to the Supreme Court if they lose.
If the Court rules in the plaintiffs’ favor, it could establish the efficiency gap test as an official measure for gerrymandering in all states. But in addition to having a measurement for how extreme gerrymandering is in any given state, the Court would have to actually define how big an efficiency gap would have to be in order to be unconstitutional.
Stephanopoulos’s and McGhee’s recommendation: 8 percent as the threshold for statehouses, and whatever percentage adds up to at least two seats for congressional maps.
By that measure, Florida, Ohio, Pennsylvania, and Virginia all have congressional maps that violate voters’ constitutional rights. At the state level, this measure would invalidate political boundaries in Idaho, Indiana, Kansas, Massachusetts, Michigan, Missouri, North Carolina, Ohio, Oklahoma, Rhode Island, Virginia, Wisconsin, and Wyoming.
These states won’t all necessarily have to draw new maps if Wisconsin’s Assembly map is ruled unconstitutional, though. The plaintiffs base their argument against Wisconsin’s map heavily—though not solely—on the efficiency gap measurement. Stephanopoulos said it’s possible a court will rule against Wisconsin’s maps without approving of this particular measurement or choosing a different percentage as the line in the sand against gerrymandering.
The efficiency-gap standard has already come under criticism. Its reliance on election results means that the standard could be thrown by uncontested races or the natural advantage that incumbents build up the longer they hold a seat, said Wisconsin Assistant Attorney General Brian Keenan, who is defending his state’s map. And if a “wasted” vote is a sign of discrimination, that would make nearly every vote for a third-party candidate a sign of gerrymandering, Keenan added.