The Supreme Court hears oral arguments Wednesday in a second key case about partisan gerrymandering, this time focusing on the way Maryland redrew a congressional district to swing it from a Republican to a Democratic seat.

The justices already heard arguments in October in a case out of Wisconsin about whether a state’s political maps can be challenged on the basis that they entrench a benefit to one political party over another. The court has never allowed such a challenge but has not ruled it out either.

But then in December, with that case still undecided, the Supreme Court announced it also would decide a version of the same issue from Maryland focused on the 6th District. Currently, Inside Elections with Nathan L. Gonzales rates the race to replace retiring Democratic Rep. John Delaney “Solid Democratic” for November.

Michael Kimberly, the lawyer who will argue Wednesday on behalf of Maryland voters who brought the case, said that Gov. Martin O’Malley and other top state officials who redrew the state’s congressional map specifically intended to dilute the votes of Republicans in the northwest section of the state. Voters there had supported Republican Roscoe G. Bartlett, the district’s representative for the preceding 20 years.

“And as it turns out, that’s what they did, and it worked,” Kimberly told reporters Monday. “Roscoe Bartlett was defeated in 2012 and no Republican has won in the district in the years since.”

The goal was to change to a map that allowed Democrats to win seven of the state’s eight congressional seats, instead of just six, Kimberly said. And he argued the result violated the voters’ First Amendment protection from being disfavored based on their political views.

The court’s eventual answer in the Maryland and Wisconsin cases, by the end of the term in June, will likely come too late for this year’s elections.

But the justices could have a huge influence on how states redraw district lines after the 2020 census, as well as on a similar challenge to congressional districts in North Carolina.

Legal experts say Wednesday’s arguments could shed light on how the Supreme Court is thinking about both cases and the broader issues, such as whether courts should get involved at all if maps are drawn too partisan — and what that line should be, and how to determine if a state crossed it.

Watch: The Many Ways to Draw a Gerrymander

Two questions

The Maryland and Wisconsin cases present different ways for the justices to approach the issue of partisan gerrymandering.

Voters in Wisconsin challenged the state’s whole state legislative map, drawn by Republicans, which they said essentially stripped voters of their constitutional right to choose their representative. The Maryland challenge focuses on just one congressional district, drawn by Democrats, on a First Amendment challenge.

Maryland’s attorney general, Brian Frosh, argued in a brief that the challenge’s theory is “novel.” The new lines made the 6th District more competitive and returned it to a configuration consistent with its history, the brief states.

The Maryland voters’ brief counters that two metrics say Bartlett had a 99.7-to-100 percent chance of winning re-election in 2010, but redistricting made it 92.5-to-94 percent likely that a Democrat would win in 2012.

“No other congressional district anywhere in the nation saw so large a swing in its partisan complexion following the 2010 census,” the brief states.

The Maryland and Wisconsin cases haven’t been the only Supreme Court action on partisan gerrymandering. The justices this month declined a request from Republican lawmakers in Pennsylvania to stop a ruling from that state’s Supreme Court.

The state court ordered a new congressional map for the 2018 elections after finding the previous 2011 map drawn by the Republican-controlled General Assembly represented an unconstitutional partisan gerrymander.