Shelby County v. Holder was a June 25, 2013, Supreme Court decision that struck down the formula used in Section 4 of the Voting Rights Act as unconstitutional.
”The conditions that originally justified these measures no longer characterize voting in the covered jurisdictions,” Chief Justice John Roberts wrote in the majority opinion in Shelby. Interestingly, the opinion gave the VRA itself credit for the status of racial discrimination in voting, noting, “these improvements are in large part because of the Voting Rights Act.”
So Shelby didn’t declare the preclearance requirement itself unconstitutional, just the formula that was used since the passage of the VRA to determine who has to be precleared. This means that until Congress passes legislation with a new formula for preclearance under Section 4 — which doesn’t look likely to happen anytime soon — jurisdictions that were covered by the previous formula are free to make election changes without any need to get approval from the federal government.