Any vote cast for a losing candidate is counted as “wasted,” as are votes for a winning candidate beyond the number needed to win.

The formula divides the difference between the two parties’ “wasted” votes by the total number of votes to come up with the “efficiency gap.”

In 2012 – the first election after redistricting – the formula calculated the gap to be a 13 percent advantage for Wisconsin Republicans. Plaintiffs in the case argued that anything above 7 percent should be deemed unconstitutional.

In 2012, Democrats claimed 51 percent of the vote for Wisconsin state Assembly to 49 percent for Republicans. The GOP, though, won 60 of 99 seats.

The ruling from the federal court stated: “Although Wisconsin’s natural political geography plays some role in the apportionment process, it simply does not explain adequately the sizable disparate effect” on voting results that followed reapportionment.

In January, the federal panel ordered the Wisconsin Legislature to submit redrawn districts in time for the 2018 election, declaring: “The people of Wisconsin already have endured several elections under an unconstitutional reapportionment scheme.”

On Feb. 24, Wisconsin’s attorney general appealed the panel’s finding to the U.S. Supreme Court, asking it to reinstate the GOP-drawn legislative boundaries.

The Republican attorney general, Brad Schimel, argued that Democrats are geographically clustered in higher numbers in cities like Madison and Milwaukee, while comprising the minority in outlying districts.

Districts favor Republicans

But if there’s a case in Wisconsin for unfair partisanship in redistricting, Michigan’s election results by this metric look to be just about as partisan – or worse.

Under the same formula used in the Wisconsin case, a Bridge Magazine analysis found the “efficiency gap” favoring Republicans to be 10.1 percent in the 2016 state House races, 15.5 percent in the 2016 races for Congress and 22.8 percent in the 2014 races for state Senate.

Nicholas Stephanopoulos, the University of Chicago law professor who helped develop the mathematical voting standard used in the Wisconsin case, said Michigan's efficiency gap puts it in rare company. He said research for the lawsuit into other state legislative races in the past decade found just 1 or 2 percent of those races with gaps above 20 percent.

“It’s quite clear that Michigan is just as extreme an example as Wisconsin,” he said.