The Supreme Court will hear arguments Tuesday in the case Common Cause versus Rucho. Common Cause and the League of Women Voters say the state's congressional map is an unconstitutional partisan gerrymander.

The U.S. Supreme Court will hear arguments Tuesday in a North Carolina gerrymandering case that could determine how far state legislatures can draw maps to maximize one political party’s advantage over another.

The case - Common Cause versus Rucho - focuses on North Carolina’s 2016 congressional map, which helped Republicans win 10 of 13 congressional seats that year.

The plaintiffs, Common Cause and the League of Women Voters, use words like “extreme” and “brutal” to describe North Carolina’s congressional map, which packs Democrats into three of the state’s 13 districts. In some cities, Republicans “cracked” Democratic voters, diluting their strength by splitting them into Republican-majority districts.

One of their most critical pieces of evidence is from Republican state representative David Lewis of Harnett County. Three years ago, he said the GOP would have drawn a map with 11 Republicans and two Democrats if that was possible.

"I acknowledge freely that this would be a political gerrymander which is not against the law," Lewis said. "I propose that we draw the maps to give a partisan advantage to 10 Republicans and three Democrats because I do not believe it's possible to draw a map with 11 Republicans and two Democrats."

Attorney Allison Riggs, who will argue on behalf of the League of Women Voters, said Lewis' comment is "the most devastating smoking gun evidence."

She added: "If you are in Black’s Law Dictionary, and there was an entry for 'smoking gun,' there would be a picture of David Lewis."

[Related: Bill Would Take Legislative Map-Making Away From General Assembly]

The Supreme Court has ruled that legislatures can’t gerrymander based on race – but it hasn’t definitively weighed in on how far maps can be drawn based on political party.

Common Cause will, for the most part, argue that the map violates the First Amendment in that if elections are pre-ordained, people’s speech, or vote, is suppressed. The League of Women Voters will argue the map violates the 14th Amendment’s equal protection clause, which requires that the government treat all citizens the same.

Paul Clement, who will argue for North Carolina Republicans, did not return phone calls.

Last year, the Supreme Court heard a similar case about Wisconsin’s state house map, which favors Republicans. In that case, Gill versus Whitford, Misha Tseytlin argued for the of Wisconsin and said a judicial intervention would just shift the issue to the courts.

"This court has never uncovered judicially manageable standards for determining when politicians have acted too politically in drawing district lines," he said during the Wisconsin hearing. "Plaintiff's social science metrics composed of statewide vote to seat ratios and hypothetical projections do not solve any of these problems. Instead, they would merely shift districting from elected public officials to federal courts, who would decide the fate of maps based upon battles of the experts."

At first glance, North Carolina’s congressional map doesn’t look particularly crazy – there are no districts that snake across the state, as though they were a piece of modern art. It was created in 2016 after the state's previous map from 2011 was ruled an unconstitutional gerrymander based on race.

The map may look normal, but it helps Republicans by cracking Democratic voters in large cities.

Asheville is split, and so is Fayetteville.

Close to home, the legislature placed all of Mecklenburg County in the 12th District, except for the Republican-leaning precincts in south Charlotte. Those were placed in the heavily revised 9th District – a move designed to offset black Democratic voters in Anson and Robeson counties.

The 9th District was held by Republicans after the 2016 election and was the GOP’s 10th Congressional seat. It’s unclear which party will hold it because there is now a special election after the state board of elections said there was absentee mail ballot fraud last fall that benefited the Republican candidate, Mark Harris.

Greensboro is also one of the most severely cracked cities, says Bob Phillips of Common Cause. Greensboro is a Democratic city, but it's split into the 6th and 13th districts, both held by Republicans.

"That line actually divides the campus of North Carolina A&T, literally dorms are split, where you have dorms in one congressional district, and across the street, dorms in another," Phillips said.

In addition to Lewis’ admission, Common Cause and the League of Women Voters have leaned on the work of a Duke mathematician, Jonathan Mattingly, who created more than 20,000 North Carolina congressional maps, based on some of the criteria the state used, like keeping counties whole. A 10-3 Republican map occurred in less than 1 percent of his maps.

"It was vanishingly many, vanishingly many," Mattingly said. "It was a tiny number, a tiny fraction. It basically rarely happened, if ever."

In August, a three-judge panel last fall ruled in favor of Common Cause and ordered new districts to be drawn immediately.

The Republican legislative leadership appealed, saying that new maps before the 2018 midterms would produce chaos.

The Supreme Court’s decision to hear the North Carolina case is a victory for Republicans. The court could have let the lower court ruling stand – and the state would likely already have new maps in place.

The plaintiffs must now argue before a court that has a 5-4 conservative majority after Brett Kavanagh was appointed last year.

Here’s one question conservative justice Neil Gorsuch raised in the Wisconsin case.

"What criteria would a state need to know in order to avoid having every district and every case and every election subject to litigation?" he asked. "Because the standards given in the lower court here was, well, a little bit of partisan symmetry problem, a little bit of an efficiency gap problem, not a real set of criteria."

The court postponed a final decision on the Wisconsin case until it rules on the North Carolina gerrymandering case, as well as a similar case from Maryland that will also be heard Tuesday. That state’s map favors Democrats.

A ruling on Common Cause vs Rucho is expected this summer.

