Lansing — An analysis pinpointing Michigan as one of the most gerrymandered states in the nation is providing new fuel for groups looking to challenge political boundaries in court or change the process at the ballot box.

State House and congressional districts redrawn by Michigan Republicans after the 2010 census report resulted in one of the most lopsided political advantages or “efficiency gaps” in the country last year, according to the Associated Press review.

The measurement of partisan advantage “is motivation” for Voters Not Politicians, a grassroots group pursuing a potential ballot proposal to create a non-partisan redistricting commission in Michigan, said spokeswoman Katie Fahey.

“I think people see there is an inherent unfairness, and I think everybody recognizes too that it’s very short-sighted to be manipulating the lines that way, because either party can do that and leave voters on the other side disenfranchised,” she said.

But after forming in February, the self-proclaimed bipartisan Voters Not Politicians has yet to unveil its petition language and raised $50,725 through April 20, according to a state disclosure report.

A judgment on partisan election advantages is likely to come soonest from the U.S. Supreme Court, which is preparing to take up a challenge in Wisconsin that experts say could have broad ramifications for Michigan and other states.

Wisconsin’s GOP-led Legislature crafted maps in a way that “systematically dilutes the voting strength of Democratic voters statewide,” according to a 2-1 7th Circuit U.S. Court of Appeals decision.

Justice Anthony Kennedy, a Republican appointee, is expected to be the deciding vote in the Wisconsin case.

Kennedy has said he is open to an accurate measurement for gerrymandering. The justice might be persuaded that gerrymandering is worse now than in past decades based on the efficiency gap methodology, but “he was very skeptical that such a formula existed,” said Nicholas Goedert, an assistant professor of political science at Virginia Tech University.

Former Michigan Democratic Party Chairman Mark Brewer said he is watching the nation’s High Court closely while planning to sue state officials over the political maps.

The Associated Press findings “reinforce our analysis that Michigan is among the worst, if not the worst partisan gerrymander in the country,” Brewer said.

Republican experts said the voluntary grouping of huge Democratic majorities in urban areas such as Detroit and Flint skews the picture of partisan advantage.

Michigan’s ‘wasted votes’

The AP contracted with experts who found Michigan’s “efficiency gap” in 2016 state House elections was the second largest in the country. Republicans here returned a 16-seat majority despite essentially splitting the statewide vote total with Democratic candidates.

Michigan’s congressional efficiency gap ranked ninth largest in the nation, as Republicans won nine of 14 U.S. House seats while edging Democratic candidates by a combined 1.1 percentage point.

The calculations are based on a mathematical formula developed by University of Chicago law professor Nick Stephanopoulos and Eric McGhee, a researcher at the Public Policy Institute of California.

The efficiency gap measures “wasted votes” for losing candidates and extra votes for winning candidates beyond the amount they needed to secure victory. A large gap indicates a structural advantage through district boundaries for a party that wins many seats but wastes few votes.

Brewer said he plans to use the efficiency gap results in his pending Michigan lawsuit and praised the approach in the Wisconsin case, where attorneys used it as “corrobarative evidence” rather than an exclusive focal point.

Others say it isn’t foolproof. The efficiency gap is a useful tool for measuring the partisan leaning of a map but doesn’t always tell the whole story, said Jowei Chen, an associate professor of political science at the University of Michigan.

Chen used computer simulations to analyze 2012 congressional elections and found that while partisan gerrymandering was “quite severe” in some states, it only increased Republican control of the U.S. House by one or two seats because Democrats also slanted maps in states such as Illinois and Maryland.

“A more important explanation of why Republicans have dominated the U.S. House in recent elections is voter geography,” he said.

“Democratic voters tend to be heavily clustered in a relatively small number of dense, heavily left-wing industrialized urban districts in cities like Philadelphia, Baltimore, Chicago, and Miami. Meanwhile, Republican voters are more evenly spread out across a larger number of moderately conservative suburban and rural districts, allowing Republican candidates to efficiently win more districts without wasting as many votes.”

The efficiency gap fails to account for natural divisions that occur when Democrats self-cluster in cities, said Bob LaBrant, a Republican attorney who has played a key role in Michigan redistricting efforts since the 1980s. Lopsided votes for Democrats in large cities are counted as wasted votes under the efficiency gap.

“As long as you have Democrats packed into urban districts, you’re going to have high scores, but traditional standards generally find that districts that are contiguous and compact and follow political subdivision boundaries are not evidence of partisan gerrymander,” LaBrant said.

“I think the two individuals who came up with the efficiency gap have done a good job of marketing it, but I don’t think it has much of an impact on how the U.S. Supreme Court is going to view this.”

How to measure bias?

Experts said the Wisconsin case could prove a landmark legal test. But in agreeing to hear oral arguments, the Supreme Court temporarily suspended a lower court order that Wisconsin redraw its legislative maps this fall, suggesting the conservative majority may side with the state.

In a 2004 High Court concurrence, Kennedy noted that there was no “workable standard” to prove the existence of a partisan gerrymander but suggested he would be open to considering a measurement should one emerge.

Attorneys in the Wisconsin case argued the efficiency gap is a viable measurement of partisan bias.

LaBrant said he does not think Kennedy will find the measurement persuasive. He noted the lower court decision focused more on legislative intent in Wisconsin than the efficiency gap.

Goedert said he is no fan of partisan gerrymanders but does not believe courts should use the efficiency gap to determine the constitutionality of maps, in part because the measurement can only be made after an election has happened.

“The maps that look biased in favor of Republicans one year might actually look biased in favor the Democrats another year,” he said, suggesting a large swing could hurt a political party that had drawn itself into more competitive districts to avoid wasted votes.

“Whether a map would be constitutional or unconstitutional using the efficiency gap measurement could depend a lot on public opinion waves.”

Most states allow their state legislatures to redraw political boundaries every 10 years after census results. A party with a legislative majority at that time controls the process, and Republicans made a concerted national effort to win legislative majorities at the turn of the decade.

“In the vast majority of states, Democrats have just been taken to the cleaners by Republicans who have used reapportionment to give themselves an advantage in elections,” said Bill Ballenger, a longtime Michigan political observer and former GOP legislator.

Michigan Democrats largely controlled the maps in the 1960s and 1970s because they had majorities on courts that ultimately drew them after legal challenges. Courts again decided the maps in the 1980s and 1990s, relying on principles developed by state elections staffer Bernie Apol.

Those standards were codified into law in the 1990s under legislation sponsored by then-state Sen. Bill Schuette, a Midland Republican who is now attorney general and considering a run for governor.

Asked if Schuette still believes the legislation is capable of combating gerrymandering, his office declined comment, citing the possibility of future litigation over Michigan redistricting.