JIM LO SCALZO / EPA Ryan Haygood, the director of the NAACP Legal Defense and Educational Fund, gathers with civil rights activists outside the Supreme Court to protest the decision to strike down part of the Voting Rights Act of 1965 in Washington on June 25, 2013

The Supreme Court delivered a sucker punch to fair elections today, striking down a key part of the Voting Rights Act. It is a ruling that will make it much easier for partisan election officials and legislators to rig the voting system — and a lot harder for ordinary voters to participate in democracy.

The ruling is also a huge Supreme Court power grab. How big? In 2006, Congress reauthorized the Voting Rights Act by a vote of 98-0 in the Senate and 390-33 in the House (and President George W. Bush signed it into law). Now, five Justices have swept away the decision of all those elected leaders — over the vociferous dissent of four other Justices.

At his confirmation hearing, Chief Justice John Roberts — who wrote today’s majority opinion — famously declared that as a Justice, “my job is to call balls and strikes and not to pitch or bat.” But in nullifying one of the most important pieces of civil rights legislation in U.S. history, he picked up a bat and swung for the bleachers.

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The part of the Voting Rights Act that the court held unconstitutional (Section 4) was a critical one: the formula that specifies which particular states and localities must clear significant voting changes in advance with the Justice Department. That process — “preclearance” — ensures that unfair voting rules can be stopped before they are allowed to interfere with actual elections.

An example of why it’s needed: in 2001, the all-white leadership of Kilmichael, Miss., abruptly canceled the town election when it looked like voters might elect the first black mayor. Using the Voting Rights Act, the Justice Department required that the election go forward — and a black mayor was elected. That was only one of more than 700 discriminatory voting changes the Justice Department blocked from 1982 to 2006.

The Supreme Court’s majority was troubled by the specific states and localities that the Voting Rights Act’s “preclearance” rules apply to. Why Alabama and not Vermont? Why Brooklyn and the Bronx, but not Lincoln, Neb.? The simple answer is that these are the jurisdictions Congress chose after careful consideration. It held 21 hearings and heard from scores of witnesses — it produced a 15,000-page record — before reauthorizing the law in 2006. Without doing any of that work, five Justices have said they know better.

Now that the formula has been thrown out, the whole process of preclearance is effectively thrown out as well. In theory, Congress could come up with another formula — and a list of states and localities — that the Supreme Court would find constitutional. But it would be a legislative nightmare for Congress to try to do that — and no one expects that to happen anytime soon.

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So what does the gutting of the Voting Rights Act mean for American democracy? It will be easier for bad-apple election officials to revive classic vote-suppression tactics — like moving polling places at the last minute, so voters cannot find them, or getting eligible voters off the rolls. And it will be easier for state legislatures to draw district lines to divide up minority voters and dilute their power at the polls.

The majority dismisses all these very real concerns, arguing that “things have changed” since the bad, pre-civil-rights-era days. Of course, even if that were so, it would not mean that we don’t need the Voting Rights Act. As Justice Ruth Bader Ginsburg wrote for the dissenters, that sort of logic is “like throwing away your umbrella in a rainstorm because you are not getting wet.” Now that the Supreme Court has gutted the Voting Rights Act, we should get ready for an antidemocratic downpour.

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