LOUISIANA — In Louisiana v. Callais, the U.S. Supreme Court ruled that plaintiffs challenging racial vote dilution under Section 2 of the Voting Rights Act must control for party affiliation when proving racial bloc voting. The Court held that to satisfy the second and third preconditions established in its 1986 Gingles v. Thornburg decision, plaintiffs must demonstrate that racial bloc voting cannot be explained by partisan affiliation.

Justice Samuel Alito authored the majority opinion. Alito described Louisiana v. Callais as merely an "update" to the evidence required under Section 2 of the Voting Rights Act to challenge racial vote dilution. He stated that the Court was not "abandoning" the prior framework that had authoritatively construed Section 2 for decades.

The 1982 amendments to the Voting Rights Act replaced an intent-based standard with a "results" test, prohibiting voting practices that "result[]" in an abridgement of the right to vote "on account of race or color." Under the Gingles preconditions, plaintiffs must show that minority voters are sufficiently compact to form a reasonably configured district and that racially polarized voting exists—meaning minority voters are politically cohesive and white voters typically vote as a bloc to defeat minority-preferred candidates.

Brian Clardy, professor of history at Murray State University, said, "Both decisions represent conservatism that privileges hate and white supremacy, Plessy after Reconstruction, Callais after civil rights legislation in the 1960s that was called a second Reconstruction." William Mulligan, history professor emeritus at the same institution, added, "The Callais decision continues a troubling trend – reversing decisions that have expanded the definition of who receives full rights and equal treatment." Mulligan also proposed that the Court’s conservative majority might heed Justice Louis D. Brandeis’ argument that what matters most is the result of a law or a decision.