The Supreme Court Case That Could Hand the House to Republicans

Republicans have been redrawing congressional districts this year at President Trump’s behest, but so far it hasn’t seemed to be enough to deny Democrats a reasonable path to control of the House of Representatives.

That might change if the Supreme Court strikes down Section 2 of the 1965 Voting Rights Act in Louisiana v. Callais, a case the court heard Wednesday.

Without Section 2, which has been interpreted to require the creation of majority-minority districts, Republicans could eliminate upward of a dozen Democratic-held districts across the South.

Republicans may not eliminate every Democratic-leaning district that they technically could (more on why later), but the party’s aggressive mid-cycle redistricting suggests they would eliminate enough to obtain a significant structural advantage. It’s not clear whether this would occur by next year’s midterm elections, with a court ruling likely next summer, but the new seats would eventually be enough to make Republicans favored to win the House even if they lost the popular vote by a wide margin.

Despite all the gerrymandering by both political parties in recent years, neither has been able to obtain a significant structural advantage in the House so far this decade. In two very close elections, the party that won the most votes won the most seats. That’s partly because each side’s gerrymanders canceled the other’s out, but it’s also because the two major legal limitations on gerrymandering — state redistricting laws and Section 2 — have also canceled each other out.

While state laws restricting gerrymandering have mostly been enacted by Democrats in blue and purple states, Section 2 is the main legal limitation on gerrymandering in many red states, particularly in the South. It bans voting practices that discriminate based on race, which has been interpreted to require the creation of majority-minority districts in areas with racially polarized voting and where minority groups represent a majority of the population. Without Section 2, many state legislatures would be free to eliminate majority-minority congressional districts, which mostly vote Democratic.

It’s hard to say exactly how many districts Republicans would eliminate if Section 2 falls. It’s also hard to say whether Republicans would be able to eliminate those districts before next year’s midterms; the Supreme Court’s decision is likely to come after many state primaries. The full fallout from the decision might not come until 2028 or even after the next census in 2030.

But even on the lower end of the estimate, Republicans will probably eliminate around a half-dozen districts: the majority Black districts in otherwise overwhelmingly Republican states and regions of the Deep South. In these reliably red states, Republicans could eliminate every Democratic-held majority-minority district while ensuring that the new districts remain relatively compact and overwhelmingly Republican.

With Mr. Trump already pressuring Republicans to undertake an aggressive mid-cycle redistricting effort, it would not be surprising to see Alabama, Mississippi, South Carolina, Louisiana and Tennessee attempt to eliminate every Democratic district. Additionally, without Section 2, North Carolina’s current plan to dismantle its First District would pass legal muster. And Florida Republicans might be tempted to target the state’s Ninth District in its coming redistricting push.

After those seven or eight seats, things get a little fuzzier. On paper, Republicans could go much further and eliminate another half-dozen seats or more in Texas, Georgia, Missouri and Florida. Republicans might pursue these options, especially with Mr. Trump pressuring them to do so, but other factors would begin to weigh on their calculus.

One limiting factor is that Republicans can’t eliminate every majority-majority district without endangering Republican incumbents. This is especially true in relatively competitive states like Georgia or Texas, where Republicans must preserve some number of Democratic districts to ensure that every Republican incumbent represents a safe district. It’s also true in Florida, where Republicans have the additional burden of needing to plausibly follow the state’s not-strongly-enforced Fair Districts amendment.

A second limiting factor is the cooperation of Republican members of Congress or even state legislators. It’s not always painless for Republicans to eliminate additional Democratic seats, and Republican officials may not support more aggressive gerrymanders, even if they’re mathematically possible.

A maximum gerrymander in Texas, for instance, might require a near total reconfiguration of the state’s congressional map, with outlandishly shaped districts snaking from the center of major metropolitan areas all the way to the border of neighboring states. Republican incumbents might balk at losing their longtime constituents and donors if they suddenly represent a very different area, and they might fear primary challenges in the new districts. State legislators might not want to defend a new map against criticism from their voters.

This may not seem like a serious concern. After all, Republicans have attempted many gerrymanders in recent years. But those same gerrymanders have demonstrated that there are limits to how far they will go. This year, there was significant Republican opposition to the efforts to redraw the congressional maps in Missouri and Indiana. In Georgia in particular, the G.O.P. doesn’t have as much room to survive Republican defections.

Even the successful Republican redistricting efforts sometimes show the hallmarks of a party running up against the tolerable limits of gerrymandering. The existence of a Democratic seat in Austin is one clear case. Legally, Texas Republicans could eliminate it today; it’s majority white. Mathematically, Republicans could eliminate it by extending even more Republican districts into the city, like a pinwheel centered on Austin. But there hasn’t been much appetite to do so.

Still, Republicans wouldn’t need to flip so many districts to deal an enormous blow to Democratic chances. Even in the seven-to-eight-seat scenario, Democrats might need to win the popular vote by five percentage points to merely have a 50-50 shot to win the House.

In recent decades, five-point victories in the House popular vote have generally happened during “wave” elections, like in 1994, 2006, 2010 and 2018, when one party ends up winning a large majority. And only once in the past 30 years has it happened during a presidential election year: Barack Obama’s win in 2008.

But if Section 2 falls, and Republicans redraw districts across the South, Democrats will be at enough of a structural disadvantage that even with a five-point victory, their chances might depend on upsets in a few heavily Republican districts.

Additional work by Amy Fan, Francesca Paris and Jonah Smith.