In other places with similar histories of discrimination, officials have closed polling places, creating longer lines and making it difficult, if not impossible, for people in minority communities to vote. In Texas, the number of voting locations has been reduced by more than 400. In Arizona, nearly every county closed at least one voting location; about 60 percent of counties in Louisiana and numerous counties in Alabama did so as well. A vast majority of these closings would have been blocked had the Voting Rights Act not been eviscerated by the Roberts Court.

That law had required nine states and many counties with long records of voting discrimination — primarily in the South, but also in places like Arizona, Alaska and New York — to seek federal approval, or preclearance, before making changes to their laws. Hundreds of discriminatory laws and practices were blocked over the years — until 2013, when the Supreme Court struck down the preapproval requirement, as applied to those states and counties, as no longer addressing “current conditions” and as an unconstitutional burden on state sovereignty.

Why? Because “things have changed dramatically,” according to Chief Justice John Roberts Jr., who wrote the 5-to-4 majority opinion in Shelby County v. Holder. With that decision, he and the other justices in the majority set back the cause of racial equality at the voting booth by decades.

The past three years have confirmed just how naïve the chief justice’s words were. Right after the court’s decision, lawmakers in North Carolina passed a stunningly broad anti-voter law, while Texas revived its own absurdly strict voter-ID law that had already been blocked by the federal government.

Last summer, federal appeals courts found that both states’ laws discriminated against minorities, but voters, poll workers and government officials were confused, even on Election Day, about what the current rules were.