As Democrats struggled last week to salvage control of the Senate, they pushed to get as many black voters to the polls as possible, especially in the South. It’s no wonder: Blacks are the most reliable Democratic voters, and 89 percent of them ended up supporting Democratic candidates in the 2014 elections (a mark that was actually down from 2012). White voters, in contrast, came out heavily for Republicans in the South. In North Carolina, where incumbent Democrat Kay Hagan lost to Republican Thom Tillis, the GOP candidate got just 3 percent of the black vote. But as we all know, the black turnout was not high enough to beat back the Republican wave in North Carolina or elsewhere. In North Carolina in particular, black turnout was down compared with 2012.

Recognizing this major overlap of race and party in the South is key to understanding Wednesday’s Supreme Court case involving a constitutional challenge to Alabama’s legislative redistricting. No one disputes that the Alabama Legislature packed black voters into a few legislative districts, thus strengthening Republican control in the majority of districts throughout the rest of the state. But whether or not that action is constitutional depends a great deal on whether the court views this as a case about race (in which case Alabama may have acted unconstitutionally) or one about party (in which case Alabama’s actions are constitutional, if unsavory politics as usual).

Given current realities, this “race or party” determination is a wholly artificial exercise, but one that puts the justices in a very interesting spot.

The facts and legal circumstances surrounding the Alabama lawsuit are exceedingly complex—I have laid them all out in a detailed analysis at SCOTUSblog. To simplify greatly, the question before the court is not whether the Alabama Legislature impermissibly diluted the votes of black citizens by packing them into fewer districts. Challengers pressed that issue in lower courts but lost, and the Supreme Court refused to hear that part of the case. Instead, the challengers argue that Alabama engaged in an “unconstitutional racial gerrymander.”

Before 1993, there was no such thing in constitutional law as an unconstitutional racial gerrymander separate and apart from a claim of vote dilution. Then, in a case out of North Carolina called Shaw v. Reno, the conservatives on the court recognized a racial gerrymander as an “analytically distinct” claim based on separating voters in districts on the basis of race, often through oddly shaped districts, without adequate justification. As the claim developed, the court explained that racial gerrymandering was an “expressive harm” in which the government sends a pernicious message that race matters above all else in redistricting. Liberals rejected the claim, saying that racial gerrymandering without proof of vote dilution was no harm at all, and that there was no evidence that the shape of districts sent voters any message at all.

The racial gerrymandering claim was a way for the court to rein in the Department of Justice. At the time, the DOJ—under Section 5 of the Voting Rights Act—had authority to approve (or “preclear”) changes in voting rules in jurisdictions with a history of racial discrimination in voting. The DOJ was forcing states covered by preclearance provisions to create more districts in which minority voters could elect candidates of their choice (“majority-minority districts”). Republicans brought racial gerrymandering claims to attack districting plans that favored Democrats, such as North Carolina’s. In those cases, the Supreme Court justices dutifully searched the record of legislative redistricting deliberations trying to figure out if race was the “predominant factor” in redistricting. Sometimes they decided yes, sometimes no.

These racial gerrymandering claims eventually petered out, in part because in the 2000s the DOJ (following other adverse Supreme Court rulings) stopped requiring states to create the maximum possible number of majority-minority districts. But now the racial gerrymandering claims are back. This time, they are being brought by Democrats to stop actions like Alabama’s post-2010 redistricting plan.

When Alabama drew its districts, it was still under federal Voting Rights Act preclearance. In drawing its districts, Alabama decided not only to keep the same number of majority-minority districts (something it likely had to do to get federal approval for its districts), it also decided to keep the same percentage of black voters in each of these districts. It claimed it had to do so to comply with the Voting Rights Act, a dubious argument given earlier DOJ compliance guidance and earlier practice under the act.

Further, because these black districts were underpopulated with voters and the districts lost population throughout that decade, Alabama had to move a lot of voters into these districts to comply with the Supreme Court’s requirement that states achieve something close to equal populations in redistricting. The Legislature moved loads of black voters and very few white voters into these districts, helping strengthen Republican districts in the rest of the state. As the New Republic’s Jason Zengerle shows, the result has been the demise of elected white Democrats, sending a signal to race-sensitive Alabama voters that if they’re voting for a Democrat, that means they’re voting for a black candidate.

Alabama was not alone in packing minority voters into districts this election cycle. As law professor Justin Levitt explains, many Republican legislatures did so claiming (insincerely or not) a belief that such redistricting was required by the Voting Rights Act. Democrats and civil rights groups responded by claiming these states are engaged in racial gerrymandering, by making race more important than any other factor in redistricting.

This role reversal will not be lost on the justices. Will the conservative justices, who do not like race-based government classifications at all, side with Democrats against the Republican Alabama Legislature, seeing Alabama’s actions as a racial gerrymander? Or will the Supreme Court’s conservatives, like the two Republican-appointed judges in the lower court, view this gerrymandering as partisan politics, in which the Republican Legislature packed not blacks but Democrats into fewer districts for partisan gain? (The court has long refused to police such partisan gerrymandering.) The liberal justices have an interesting choice, too. They could embrace the racial gerrymandering claims they have long resisted, breathing new life into a doctrine they have derided as nonsensical. Or they could leave Alabama’s gerrymander alone, strengthening Republican hands.

The issue is further complicated by the fact that, thanks to the Supreme Court’s 2013 decision in the Supreme Court’s Shelby County case, Alabama is no longer subject to preclearance under the Voting Rights Act. It is hard to see how to justify separating voters on the basis of race under a law that the conservatives on the court later struck down as unconstitutional. Indeed, the dissenting Democrat-appointed judge saw a “cruel irony” in Alabama’s reliance on the Voting Rights Act to justify its argument: “Even as it was asking the Supreme Court to strike down the requirement of preclearance for failure to speak to current conditions, the State of Alabama was relying on racial quotas with absolutely no evidence that they had anything to do with current conditions, and seeking to justify those quotas with the very provision it was helping to render inert.”

In the end, the Supreme Court has an impossible task in front of it: figuring out whether the Alabama Legislature’s predominant motive in redistricting was about race or about party. It was surely about both, and trying to pretend that packing black Democratic voters into districts is about just one or the other is a fool’s errand. But it is the task of the court under the rules it has set up for itself, and it could have real consequences for not just black Democrats in Alabama, but all Americans.