Cartography is having its day in court and the outcome could make a big difference in American voters’ lives. Map making is a political act, and today (Oct. 3) the US Supreme Court heard oral arguments in a case that essentially asks, “What is a fair map?”

The nine Supreme Court justices entertained arguments in Gill v. Whitford (pdf), a case arising from Wisconsin’s 2010 Republican redistricting efforts, which Democrats say has led to unjustified election success for the right. The plaintiffs (now appellees in the Supreme Court), including retired law professor William Whitford, argued that the GOP’s method for making Wisconsin’s electoral map, dividing the districts politically to create partisan advantages in state elections, consistently skews election results for Republicans and will continue to do so into the future.

Republicans won majorities in both houses of the Wisconsin legislature and the governor’s office in 2010. That gave the party the ability to redraw the voting districts in Wisconsin, and though the method the state GOP adopted adheres to traditional redistricting principles, the outcome leads to skewed results, challengers argue.

As Amy Howe explains in SCOTUS Blog, in the 2012 elections, Wisconsin Republicans won less than half of the vote but got 60 seats in the state’s 99-seat assembly while Democrats, with over half the vote, garnered only 39. In 2014, Republicans won 52% of the vote and 63 seats in the state legislature, while Democrats won 48% of the vote and 36 seats.

The practice of redistricting to a party’s advantage is called gerrymandering, and it’s inevitable to a limited extent. Lines must be drawn, and the considerations that go into drawing them influence election results. Votes from one party or another can be diluted by dividing districts in two ways: “cracking” and “packing.” Cracking splits a party’s supporters into multiple districts in which they can’t form a majority. Packing is the opposite, putting many of a party’s supporters in just a few districts. In those packed districts, a politician may win by a landslide, essentially wasting support that was needed to succeed in other districts.

The issue in Gill v. Whitford is whether these efforts can be so extreme as to be unconstitutional. Whitford argues that Wisconsin’s method of redistricting diluted Democratic votes and leads to non-representative government—that Wisconsin’s partisan gerrymandering deprived citizens of their constitutional right to a vote with value, a principle also known as “one person one vote.” By packing and cracking districts, Whitford says, the votes of individual Democrats came to mean less than those of individual Republicans. His challenge was successful in the lower courts, but Wisconsin appealed, and on June 19, the highest court in the US agreed to review the matter.

Beverly Gill of Wisconsin’s Election Commission, in her brief, argued first that the case shouldn’t even be heard, and standing was the first issue discussed at oral arguments today. Gill says that Whitford and other plaintiffs can’t sue because they’re not living in districts impacted by politically partisan gerrymandering, since they are represented by Democrats (Whitford lives in the Madison voting district). The state argues that the plaintiffs may only challenge their own districts’ cartography, rather than the whole state map.

Wisconsin also argues that the district court failed to apply a standard set in a previous Pennsylvania political gerrymandering case that made it all the way to the high court in 2003, Veith v. Jubilerer. There, the Supreme Court found “gerrymandering claims are nonjusticiable because no judicially discernible and manageable standards for adjudicating such claims exist.” Gill argues that this means redistricting is a political question, not a matter for the courts to decide, because there are no straightforward standards that could be uniformly applied to resolve such disputes. If it was something for courts to adjudicate, then every single redistricting effort would end up challenged in court and decided by judges, leading to chaos around the nation.

Whitford disagrees. He believes political gerrymandering can be addressed with a three-part test:

the intent in making the map whether redistricting has a discriminatory effect whether there is a legitimate justification for the cartography

Wisconsin’s current map, Whitford argues, was made with the intent to discriminate, and had a discriminatory effect by diluting Democratic votes with packed and cracked districts. He says that there is no legitimate justification for the map, which splits more counties than any other map in Wisconsin’s history and creates unusually unwieldy districts.

Whitford’s attorney, Paul Smith, argued today before the Supreme Court that in order to ensure future electoral maps are fair, and that non-representative government doesn’t get entrenched, we need “a method by which the extreme gerrymander, the one that is fundamentally antidemocratic and is going to last for the full decade, can be identified and held unconstitutional.”

Justice Neil Gorsuch seemed frustrated by this request, indicating he didn’t think a fair formula could be found, and that the lower court’s decision that Wisconsin’s map’s was unconstitutional was erroneous. He asked:

So, Mr. Smith, what is the formula that achieves that? Because the Court below didn’t rely on efficiency gap entirely. It looked also at the partisan symmetry test. It reminds me a little bit of my steak rub. I like some turmeric, I like a few other little ingredients, but I’m not going to tell you how much of each. And so what’s this Court supposed to do, a pinch of this, a pinch of that?

Of course, there’s more at stake here than the justice’s steak. The case has major implications for American politics. If the Supreme Court finds Wisconsin’s map took political gerrymandering to an unconstitutional level, such efforts elsewhere will have to be tempered or risk similar challenges. On the other hand, if the state succeeds in convincing the court that its cartography was constitutional, political parties will surely scramble to algorithmically redraw territories to their advantage, arguably ultimately undermining American democracy. A decision is expected by the end of June 2018.

Read next: What is gerrymandering? A guide to understanding the case before the Supreme Court