The Supreme Court on Monday evening overturned a New York state court ruling that found that the Staten Island-based district of Republican US House Rep. Nicole Malliotakis discriminated against Black and Latino voters and needed to be redrawn. The Supreme Court’s intervention preserves a GOP-led seat that would have been likely to shift to Democrats this November.

The court’s ruling sets a disturbing precedent for voting rights in several ways. Federal courts are supposed to defer to state courts on matters of state law. And the Supreme Court has repeatedly ruled that courts should not change election laws in the middle of an election season, and in this instance the filing deadline for candidates in New York has already passed.

In her dissenting opinion, which was joined by Justices Ketanji Brown Jackson and Elena Kagan, Justice Sonia Sotomayor blasted the court’s conservative majority for using one set of rules to uphold redistricting maps that benefit white voters and Republicans in states like Texas while using a completely different set of rules to strike down maps that benefit racial minorities and Democrats in places like New York.

“Time and again, this Court has said that federal courts should not interfere with state-court litigation,” Sotomayor wrote. “Time and again, this Court has said that federal courts should not meddle with state election laws ahead of an election. Today, the Court says: except for this one, except for this one, and except for this one.”