In somewhat of a surprise announcement, the Supreme Court agreed Monday to review a Wisconsin case to determine whether gerrymandered congressional district maps violate the Constitution’s 1st and 14th Amendments. The Court has traditionally avoided such cases, deeming them the purview of the political branches. The outcome could have a tremendous impact on the American electoral process.

Those who are not political or history wonks may be unfamiliar with the term “gerrymandering.” The term was first used in the March 26, 1812, edition of the Boston Gazette. A portmanteau of “Gerry” and “salamander,” it was used to describe the Massachusetts state Senate districts that were drawn by the Democratic-Republicans under Gov. Elbridge Gerry, in which his party successfully created election districts that stayed in his party’s hands despite losing the state House and governorship. One of these districts resembled the shape of the mythical salamander.

In the Wisconsin case, a dozen plaintiffs from across the state claimed “Republican legislative leaders authorized a secretive and exclusionary mapmaking process aimed at securing for their party a large advantage that would persist no matter what happened in future elections.” A three-judge panel ruled last year in the plaintiffs’ favor, declaring the Republican redistricting plan was partisan enough to effectively disenfranchise some voters. The state of Wisconsin has appealed this ruling to the Supreme Court.

Notably, this case was not brought before the federal courts until July 2015, after Republicans had taken control of state government from the Democrats. Wisconsin has long been a Democrat stronghold which, until Donald Trump narrowly won in 2016, had not voted for a Republican for president since Ronald Reagan won the state. Wisconsin’s state-level gains for the GOP are a microcosm of America generally, where Republicans made tremendous advances. During Barack Obama’s disastrous tenure, the GOP picked up nearly a thousand state legislative seats, control of two-thirds of state legislative chambers, 63 House seats, and 10 U.S. Senate seats. The Democrat Party is at its weakest electoral position in nearly a century, and is desperate for a way to reverse these losses.

The courts have largely refused to intervene in gerrymandering disputes in the past, primarily because the drawing of such districts is an inherently political act. For the courts to intervene would be to substitute the opinion of the judiciary for the opinion of the elected branches. As Supreme Court Justice Felix Frankfurter warned in Colegrove v. Green (1946), “Courts ought not to enter this political thicket. … The fulfillment of this duty cannot be judicially enforced.”

When the Court has chosen to invalidate redistricting lines in the past, it has generally done so based on the claim that the lines in question disenfranchise minority voters — that was the case just last month with two North Carolina districts. However, these cases have been few and far between. In the other most recent case — 2004’s Vieth v. Jubelirer — a 5-4 majority rejected plaintiffs’ claims, unable to delineate where normal “to the victor goes the spoils” redistricting stopped and disenfranchisement began.

Interestingly, members of the minority party often work with the majority in gerrymandering districts. While the minority party will stay in the minority, its members are drawn into increasingly safe districts, protecting them from general election challenges.

It should also be noted that both parties have engaged in such gerrymandering for more than two centuries. Even now, in addition to the Wisconsin case, a challenge to the congressional districts drawn by Maryland’s Democrats is being heard by the lower courts.

Gerrymandering doesn’t always work out for the victors though. Following the 2000 census, Georgia Democrats — with absolute control of state government since Reconstruction — gerrymandered congressional districts so “nakedly partisan” a three-judge panel modified them. In 2002, voters, furious at Democrats, elected Republican Sonny Perdue as governor, and awarded the state Senate to Republicans. The next election saw Republicans win the House. Republicans now hold supermajorities in the state House and Senate, and control every constitutional office in the state.

In these gerrymandering challenges, a move is being made to have the courts strip the power to draw districts from the elected branches and hand it to an independent panel, such as a board of retired judges equally representing both parties.

Both sides have valid arguments.

On the one hand, gerrymandering has led to safely partisan but politically polarized districts where both parties tend to cater to their base. This has made it increasingly difficult for parties to find common ground on any issues. While the Republican Party has its share of moderates, it is generally a conservative party. The Democrat Party is even more partisan, and virtually no politician supporting tax or spending cuts, or declaring themselves pro-life, can expect to survive long in that party.

On the other hand, the Constitution grants power to draw district lines exclusively to the elected branches, and to change the foundational structure of our government is not to be taken lightly.