IN an opinion brimming with a self-confidence that he hides behind a cloak of judicial minimalism, Chief Justice John G. Roberts Jr., writing for a conservative Supreme Court majority in Shelby County v. Holder, cripples Section 5 of the Voting Rights Act.

The court pretends it is not striking down the act but merely sending the law back to Congress for tweaking; it imagines that Congress forced its hand; and it fantasizes that voting discrimination in the South is a thing of the past. None of this is true.

In the Shelby decision, we see a somewhat more open version of a pattern that is characteristic of the Roberts court, in which the conservative justices tee up major constitutional issues for dramatic reversal. First the court wrecked campaign finance law in Citizens United. On Tuesday it took away a crown jewel of the civil rights movement. And as we saw in Monday’s Fisher case, affirmative action is next in line, even if the court wants to wait another year or two to pull the trigger. Imagine striking down affirmative action and the Voting Rights Act in the same week!

Section 5 of the Voting Rights Act requires certain states and parts of states (mainly in the South) to get permission from the federal government before changing voting rules. The law puts the burden on jurisdictions with a history of racial discrimination to demonstrate that any voting change — from a voter-ID law to moving a polling place — won’t make the minority voters the law protects worse off. In Section 4, Congress provided a formula for determining the jurisdictions to which Section 5 applies — but the data used to construct the formula is from the 1960s or 1970s. Congress renewed the act, most recently in 2006, without touching the old formula.