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Wednesday’s 6–3 party-line decision in Louisiana v. Callais will go down in history as one of the most pernicious and damaging Supreme Court decisions of the last century. All six Republican-appointed justices on the court signed onto Justice Samuel Alito’s opinion gutting what remained of the Voting Rights Act protections for minority voters, while pretending they were merely making technical tweaks to the act.

This decision will bleach the halls of Congress, state legislatures, and local bodies like city councils, by ending the protections of Section 2 of the act, which had provided a pathway to assure that voters of color would have some rudimentary fair representation. It’s the culmination of the life’s work of Chief Justice John Roberts and Samuel Alito, who have shown persistent resistance to the idea of the United States as a multiracial democracy, and a brazen willingness to reject Congress’ judgment that fair representation for minority voters sometimes requires race-conscious legislation. It gives the green light to further partisan gerrymandering. It protects Alito’s core constituency: aggrieved white Republican voters. It’s a disaster for American democracy.

To understand the importance of what America lost in Callais, we have to go back to a bit of history. After the Civil War, Congress passed the Reconstruction Amendments—the 13th, abolishing slavery; the 14th, requiring that states, among other things, not deny persons equal protection of the laws; and the 15th, barring racial discrimination in voting. Despite these amendments, racial discrimination was rampant in the early 20th century, and in the American South, Black citizens were consistently denied the opportunity to vote. In 1965, Congress passed the Voting Rights Act, which provided enough protection to vastly increase the opportunities for minority voters to be able to register and vote.

But the initial VRA did not deal with other problems of minority political representation, including how voters elect members of legislative bodies like city councils, state legislatures, or Congress. When........

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