A federal district court will try to decide whether to put a Maryland gerrymandering case on hold until the Supreme Court resolves a similar case involving Wisconsin’s legislative voting map. (J. Scott Applewhite/AP)

Republican voters who claim their constitutional rights were violated when Maryland redrew its congressional districts six years ago return to federal court Friday to argue that their case should move forward, even as the U.S. Supreme Court weighs a similar dispute involving Wisconsin’s legislative map.

The plaintiffs in Benisek v. Lamone allege that Democratic leaders violated their First Amendment rights by using mapping software, voter-registration data and voting history to draw a 6th congressional district that would ensure a Democratic win. The seat has been held since 2012 by Rep. John Delaney (D).

On Friday, the plaintiffs will ask a three-judge panel at the U.S. District Court in Baltimore for an immediate injunction that bars the state from using the voting map in 2018.

Late last month, Maryland Attorney General Brian E. Frosh (D) filed a motion to dismiss the case, claiming its arguments “hinge on a single false premise: Individuals who affiliate with a party have a right to maintain electoral successes gained by their party under prior redistricting maps.”

Frosh said state officials involved in redrawing the boundaries intended to make the district more competitive for Democrats rather than trying to make it unwinnable for Republicans. He argued that the plaintiffs — all registered Republican voters — have failed to show that officials who changed the boundaries specifically intended to burden the representational rights of GOP voters.

In a response to the court this week, the plaintiffs’ attorneys compared Frosh’s argument to “saying a gambler playing with loaded dice intends only to enrich himself, and not to cheat the house.”

In defending Maryland’s maps, Frosh — a Democrat in a majority-Democratic state — is breaking with others from his party who are fighting to end gerrymandering in states where Republicans have an advantage, including Wisconsin.

“If you look at the statements of the Democratic attorney general in Maryland and the Republican attorney general of Wisconsin, their statements are the same,” said former Wisconsin state senator Tim Cullen (D), who co-chairs the Fair Elections Project. “Gerrymandering has to go, regardless of which party does it.”

The Maryland plaintiffs filed a brief this week that argues against putting their lawsuit on hold, saying it is different from the Wisconsin case, that the Supreme Court should have a chance to hear both cases alongside each other, and that they would suffer “irreparable harm” in the next election if the 6th District map is not struck down.

Frosh wrote that a Supreme Court decision in the Wisconsin case would help settle and simplify many of the questions involved in Maryland’s lawsuit.

In the Wisconsin case, a three-judge panel has ruled that the state’s GOP leadership violated voters’ First Amendment and equal-rights protections through partisan gerrymandering of the state’s legislative assembly districts.

The Supreme Court has previously overturned voting maps on the basis of racial gerrymandering, ruling that such efforts violate the Voting Rights Act. But the justices have never agreed on a method for determining whether partisan ma­nipu­la­tion of voting boundaries can restrict voters’ First Amendment rights.

Gerrymandering opponents are hoping the Wisconsin plaintiffs have found an appropriate standard, which they call the “efficiency gap.”

The approach, developed by two University of Chicago professors, tries to quantify each party’s “wasted votes” — those that are either above the threshold needed to elect a party’s candidate or “lost” because voters from a particular party were placed in a district where their numbers are too small to make an impact.

Dividing the difference between the two parties’ wasted votes by the total number of votes cast determines the efficiency gap. Proponents of the measure say the gap should be close to zero and not grow drastically through redistricting.

The Maryland lawsuit does not rely on the “efficiency gap” standard. It involves a single congressional district, rather than the entire map for a state legislature.

Maryland shifted more than 360,000 residents out of the 6th District in Western Maryland in 2011, and moved about the same number of people into the district from heavily Democratic Montgomery County.

Before the new lines took effect, Republicans made up nearly 47 percent of registered eligible voters in the district, compared with about 36 percent for Democrats. After the change, Republicans made up 33 percent of registered eligible voters inside the boundary, compared with 44 percent for Democrats.

Then-Rep. Roscoe G. Bartlett, a Republican who had consistently won reelection to the district by double-digit margins over two decades, lost the 2012 election to Delaney by 21 points, in what the plaintiffs’ attorneys called “the single largest redistricting swing of any congressional district anywhere in the country.”

The plaintiffs’ legal team have deposed some of the state’s leading Democrats, including former governor Martin O’Malley, House Speaker Michael E. Busch (Anne Arundel) and Senate President Thomas V. Mike Miller Jr. (Calvert).

During his deposition, O’Malley, who led the 2011 redistricting effort, said “it was certainly my hope, and it was part of my intent” to reconfigure the 6th District so voters there would “be more likely to elect a Democrat than a Republican.”

Bush and Miller, in their depositions, denied that they sought to switch the district to the Democratic column. The speaker said he “voted for and supported what I would believe was in the best interest of the citizens of the state.”

Both leaders also said they were largely unfamiliar with detailed data that their staffs received during the redistricting process, including metrics showing the chances of Democrats winning under various configurations of the districts.

Miller said he didn’t review the information and that “it wasn’t important to me.”

O’Malley recently began advocating for nonpartisan commissions to draw voting maps. It is the same position espoused by Maryland Gov. Larry Hogan (R), who proposed legislation last year and this year to that effect.

Miller and Busch, whose party holds strong majorities in both chambers of the state legislature, have called for national or regional redistricting reform, saying they don’t want Maryland to adopt an independent process while many Republican-dominated states continue gerrymandering.