Virtually every state in the Union elects its governor and other statewide offices by popular vote. Mississippi does something different. First, a candidate must win a majority of the statewide popular vote. Second, they must also win a plurality of the vote in a majority of Mississippi House of Representatives districts. If a candidate does both, they win. If they don’t, the Mississippi House chooses the winner. As with the Electoral College, the popular vote in Mississippi only matters until it doesn’t.

In May, four black Mississippians represented by voting-rights groups filed a federal lawsuit against the state to challenge the second requirement. That “electoral-vote rule,” as they called it, “creates a system in which white-preferred candidates can win a majority of House districts with a smaller percentage of the statewide popular vote than would be required of an African-American-preferred candidate.” The lawsuit claims it violates the Voting Rights Act of 1965, the Fourteenth Amendment, and the “one-person, one-vote” rule.

The plaintiffs are unequivocally correct that the system—which does not apply to U.S. senator elections—was designed to suppress their electoral power. And yet they might still lose. Earlier this week, the state argued that the lawsuit should be dismissed under two recent Supreme Court cases on partisan gerrymandering. The lawsuit—and Mississippi’s response to it—shows how these Roberts Court rulings are already being wielded in defense of antidemocratic systems.

More than a century ago, Mississippi structured its statewide elections in this way to preserve white supremacy. The state’s white leaders adopted the electoral system when they redrafted the state constitution in 1890. They ditched the charter drafted during Reconstruction to protect multiracial democracy and replaced it with one designed to suppress black political power. Every weapon in Jim Crow’s arsenal was deployed: The new constitution imposed literacy tests, poll taxes, criminal disenfranchisement provisions, and more.

Though black voters outnumbered white voters in the state at the time, the 1890 constitution apportioned the state legislature to guarantee a majority of seats would be held by white lawmakers. That apportionment also affected the statewide election plan: Even if a black-supported candidate received a majority of votes, it would be almost impossible for him to clinch victory by also capturing a majority of the state House of Representatives districts. Lawmakers in those districts would then be able to elevate the second-place candidate to the governor’s mansion.