Alabama’s congressional district map has been in limbo since June, when the Supreme Court ruled that the State Legislature had drawn it in a way that violated a landmark civil rights law and undercut the power of Black voters.

Now, a panel of three federal judges will decide whether the legislature’s Republican supermajority, which hastily drew a new map last month, fulfilled the justices’ order to create a second majority-Black district or something “close to it.”

In the new map, Republicans chose to increase the proportion of Black voters in one of the state’s six majority-white congressional districts to about 40 percent from about 30 percent, ignoring an outcry from Democrats and Black residents.

The decision on whether the new map should stand could have national implications at a time when Republicans control the U.S. House of Representatives by a very slim margin. Should the court reject the map, a second majority-Black district in Alabama would probably elect a Democrat, since most Black voters in Alabama support those candidates.

Here’s what has happened so far.

How did Alabama decide on the original map?

Every state is required to reconfigure its congressional and state legislative districts after each census, adjusting boundaries to accommodate changes in population.

Those new districts remain in place for a decade and, depending on how much they favor one political party or another, they can affect the balance of power in the statehouse and the House of Representatives.

After the 2020 census, which showed that more than a quarter of residents in Alabama were Black, legislators maintained a map with only one majority-Black district — represented by Terri Sewell, a Black Democrat. Each of state’s six other districts has been represented by a white Republican since 2011.

Several Black voters in the state challenged the map, arguing in part that it violated the Voting Rights Act of 1965 by diluting their power and denying them an opportunity to elect a representative of their choice.

What did the courts say?

Alabama has a long, troubled history of undercutting or ignoring federal voting and civil rights laws until litigation and the courts force the state to comply. The one existing majority-Black district was created in 1992 after a lawsuit.

In early January 2022, a panel of three judges from the U.S. District Court for the Northern District of Alabama rejected the congressional map and ordered a new one drawn that would give Black voters a meaningful opportunity to elect a representative of their choice. The new map, the judges wrote, should create a second district where Black voters would be in the majority, or something “close to it.”

Alabama appealed the decision. The Supreme Court agreed to hear arguments in the case, and said the lower court’s ruling had come too close in time to the primary elections that year, so it allowed the map to be used for the 2022 midterm elections.

The case was widely seen as a test of the remaining core of the Voting Rights Act, some of whose central provisions were gutted by a 2013 Supreme Court decision. In June, the high court surprised many observers by upholding Section 2 of the law, which forbids discrimination based on race, color or language, and by ordering the Alabama map to be redrawn.

How did the Alabama Legislature respond?

Gov. Kay Ivey, a Republican, formally summoned lawmakers back to the State Capitol in Montgomery for a five-day special session in July focused on redrawing the map.

The group of plaintiffs who successfully challenged the map backed a new configuration that would create two districts with majorities of Black voters. Black Democrats in the statehouse put forward another proposal that would increase the percentage of Black voters in a second district to nearly 50 percent, arguing that a combination of Democratic-leaning voting blocs would allow Black voters there to choose their preferred candidate.

But Republicans made clear that they wanted to protect their six incumbents from potentially ugly primaries in new districts, and created a map that kept certain counties and geographic areas together for their benefit.

Their plan increased the share of Black voters in one of the state’s six majority-white congressional districts to about 40 percent, and reduced the percentage of Black voters in the one district already held by Democrats to 51 percent, from about 55 percent.

Democrats were largely cut out of the process, and opposed the final map the Legislature adopted.

What’s next?

The panel of judges will convene in Birmingham on Monday for a hearing to decide whether the Legislature’s map passes muster. It is unclear how quickly the judges will reach a verdict.

Should the court decide that a new map is required, the responsibility for drafting it will fall to a special master, Richard Allen, and a cartographer, David Ely, appointed by the court.

Mr. Allen is a longtime Alabama lawyer who has worked under several Republican attorneys general in the state. Mr. Ely, a demographer who runs a firm in California, has worked on other redistricting cases.

The verdict could have far-reaching implications across the South, where several other states confront similar redistricting challenges.