According to a new analysis by Raleigh statistician Marsh Hardy and Democratic activist Joseph Huberman, Democratic congressional candidates in North Carolina wasted more than 930,000 more votes in this year’s midterm election than Republicans did, causing Democrats to lose ten of thirteen congressional elections despite nearly splitting the statewide popular vote.

Using a mathematical formula that generates a measure of gerrymandering, Hardy and Huberman calculate that the state’s congressional races produced a so-called efficiency gap of 27.46 percent, up from a 19.3 percent efficiency gap in the 2016 elections. According to a proposed standard set forth in a 2014 article in The University of Chicago Law Review, that percentage should be about 8 percent in fairly drawn districts. In 2016, a U.S. District Court ruled in a case called Whitford v. Gill that Wisconsin’s congressional districts were unconstitutionally gerrymandered because that state had an efficiency gap of 11.69 percent to 13 percent, though the Supreme Court has not yet ruled on whether explicitly partisan—rather than racial—gerrymandering is permissible. (It overruled the federal court in Whitford by saying that the plaintiffs had not demonstrated standing while taking no position on the underlying issue.)

In this analysis, all votes won by losing candidates and all votes a winner receives over the bare majority needed are considered “wasted.” In other words, or if a candidate runs up the score, he or she has wasted all over the votes over 50 percent plus one. Likewise, a losing candidate wastes all of their votes, because those votes didn’t help them win the election.

As an example, Hardy added this sample calculation to the Wikipedia page on wasted votes:

The efficiency gap is the difference between the two parties’ wasted votes divided by the number of total votes. In the example above, it would be 39.8 percent in favor of Party A.

In the 2018 congressional elections in North Carolina—removing the District 3 race, in which Republican Walter Jones ran unopposed—Republicans wasted 382,452 votes, while Democrats wasted 1,314,081 votes out of nearly 3.4 million cast, producing an efficiency gap in excess of 27 percent. In essence, this means Democrats won fewer seats by huge margins, while Republicans won many more seats by much smaller margins.

The threshold for what constitutes gerrymandering is imperfect and controversial, as even the political scientist who devised it has acknowledged. An election could have an entirely proportional outcome—a party with 60 percent of the vote winning 60 percent of the seats—and still have an efficiency gap of 10 percent, which is higher than the 8 percent threshold the Law Review paper employed. In addition, states could have a high efficiency gap for reasons other than gerrymandering.

But it is nonetheless a useful tool for a tricky problem. Supreme Court justices have expressed interest in reining in partisan gerrymandering—or “cracking and packing,” the intentional effort to win legislative majorities by cramming large majorities of the opposition party into fewer districts. But before the efficiency gap, they didn’t have a good way to precisely measure it. Now they do.

Earlier this year—following years of rulings throwing out the legislative and congressional districts the General Assembly passed in 2011 as unconstitutional racial gerrymanders—a federal court found that North Carolina’s congressional districts amounted to an unconstitutional political gerrymander. But that decision came too late to order the General Assembly to redraw districts ahead of the election, and the case will ultimately head to the Supreme Court. With Anthony Kennedy’s retirement and replacement by Brett Kavanaugh, this current iteration of the U.S. Supreme Court seems unlikely to deem partisan gerrymandering unconstitutional.

But earlier this week, Common Cause and the North Carolina Democratic Party filed a lawsuit in Wake County Superior Court contending that the current legislative districts—even though some were redrawn last year by a special master under a federal court’s supervision—amount to partisan gerrymanders. Regardless of what the U.S. Supreme Court decides about the constitutionality of partisan gerrymandering, this new case is likely to head to the N.C. Supreme Court. The plaintiffs argue that the state constitution prohibits partisan gerrymandering—and with a 5–2 Democratic advantage on the high court, including the newly elected Anita Earls, they seem likely to prevail, and a lawsuit challenging the congressional districts seems destined to follow. The efficiency gap is likely to be central to the plaintiffs’ arguments in those cases.

It’s possible, if not likely, that the state Supreme Court will order both legislative and congressional districts redrawn before the 2020 election—and that could give Democrats a fighting chance at retaking the state House or Senate. That could have huge ramifications, as the next General Assembly will draw the district lines used for the next decade.

The ultimate question—given the tendency of Democrats to cluster in cities while Republicans sprawl out in suburbs, exurbs, and rural areas—is whether any districts could be drawn that both meet the efficiency-gap standard and other measures used to evaluate districts, such as compactness. Hardy—one of the plaintiffs in the original anti-gerrymandering lawsuit that Earls brought while she was with the Southern Coalition for Social Justice—believes they can.

“In order to reduce the efficiency gap,” he says, “districts might be shaped like pie wedges that go into urban areas. It’s still possible to make reasonably compact districts and reduce the efficiency gap at the same time.”