Members of the U.S. Supreme Court

WASHINGTON, October 3, 2017.- The Supreme Court heard a strong argument Tuesday for reining in partisan gerrymandering – at least if it’s extreme enough to allow one party’s politicians to keep themselves in power for a decade.

Better yet for the groups challenging gerrymanders, Justice Anthony M. Kennedy, who likely holds the swing vote on the issue, seemed open to ruling that extreme gerrymanders are unconstitutional.

“Politicians are never going to fix gerrymandering. You are the only institution in the United States that can solve this problem,” Paul Smith, an attorney for Wisconsin Democrats, who brought the current case, told the justices. “And this is your last opportunity” to act before the next round of redistricting following the census of 2020.

Kennedy asked a lawyer for Wisconsin’s Republicans whether it would be constitutional for the state to adopt a law that the election map will be drawn to “favor party X over party Y.”

Attorney Erin Murphy hesitated, noting that in this case, Republicans did not publicly proclaim that they were drawing a statewide map to ensure the GOP would maintain a solid majority, even though that was the effect of the district lines they created.

Kennedy was undeterred. “I’d like an answer to my question,” he said.

By the time the hourlong argument ended, it was clear that Kennedy believes the Constitution would prevent one party from writing a law designed to keep itself in power for a decade. What was unclear is whether he was convinced that the Republicans in Wisconsin had in effect done that when they went behind closed doors and drew legislative boundaries after the last Census.

The district lines the Republican-controlled legislature adopted ensured that the GOP would have a 60-vote supermajority in the state’s Assembly, the lower house of its Legislature, even if a majority of voters statewide voted for Democrats, as they did in subsequent elections.

By contrast to Kennedy, Chief Justice John G. Roberts Jr. made clear he was opposed to the court taking on the issue of partisan gerrymandering based on what he called “sociological gobbledygook.” He was referring to statistical studies that characterize the Wisconsin electoral map as highly unusual.

If the court declares the Wisconsin map unconstitutional, the justices in years to come will have to decide on a series of highly political disputes, he said.

Smith tried to assure the justices that only the most extreme partisan gerrymanders should be struck down.

The case heard Tuesday, Gill v. Whitford, is a once-in-a-decade challenge to partisan gerrymandering, a process that since 2010 has allowed Republicans to control power in at least half a dozen states where the voters are closely divided.

Wisconsin provides a textbook example. The GOP redistricting plan succeeded in preserving Republican control of the legislature despite their losing a majority of voters statewide. Federal judges ruled that the Wisconsin Republicans had gone too far and had unfairly “entrenched” themselves in power.

The high court, however, has never before struck down a state’s election districts simply because they were unfairly partisan.

If Kennedy and four other justices say Wisconsin went too far, the outcome could reach far beyond that state to potentially reshape the U.S. House of Representatives.

Pennsylvania, Michigan, Ohio and North Carolina together send 61 representatives to the House. Thanks in part to skilled line-drawing, 44 of them are Republicans and only 17 are Democrats despite voters in those states being closely divided between the two parties.

Legislative and congressional district lines in the U.S. get redrawn every 10 years, after each census. The last redistricting came after the 2010 census. In most states, elected legislators get to draw the lines, although some states, such as California, have given that power to nonpartisan commissions.

The 2010 timing was lucky for the Republicans because the elections that year were especially good for them. As a result, when the time came for redistricting, Republicans had sole control over the electoral maps in many key states. They were able to draw lines that concentrated Democrats in a handful of districts, helping to give Republicans a continuing majority.

Democrats have also used the redistricting process to help themselves, but they’ve had fewer opportunities. In Maryland, for example, seven of the eight congressional districts were drawn to favor Democrats.

The justices will hand down a decision in the case later in the court’s term.