The U.S. Supreme Court has struck down a portion of the Voting Rights Act, a Civil Rights-era law designed to prevent voter suppression in nine states and parts of seven other states.

In Shelby County, Ala. vs. Holder, the justices voted 5-4 to eliminate the law’s existing formula for selecting which places can't make changes to their elections laws or procedures without clearance from the U.S. Department of Justice. The formula has remained in place since the law’s passing in 1965.

Although the court left in place Section 5, a provision that requires states (or parts of states) to ask permission from the federal government before making changes to their elections, that part of the law has no effect without the formula. Congress would need to enact a new statute to determine which places today should be covered by the preclearance requirements in Section 5.

“Given Congressional polarization, this ruling is as big as striking down section 5 itself,” writes Rick Hasen, a political scientist from the University of California, Irvine School of Law, on his Twitter feed.

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"I think effectively it is dead," said Ilya Shapiro, a senior fellow at the Cato Institute. “I don’t see a big, controversial piece of legislation, like a coverage formula, getting through Congress.”

Chief Justice John Roberts, who wrote the majority opinion, was joined by Justices Antonin Scalia, Anthony Kennedy, Clarence Thomas and Samuel Alito. Justices Ruth Bader Ginsburg, Stephen Breyer, Sonia Sotomayor and Elena Kagan dissented. Thomas also wrote a concurrence in which he argued that Section 5 should also be struck down as unconstitutional.

The decision leaves Section 2 in place, meaning that changes to state and local elections are still subject to legal challenges, including by the U.S. Justice Department. The difference, however, is that Section 2 functions as a corrective measure after a change in law or procedure takes place, whereas Section 5 prevented a change unless the federal government certified that the change did not discriminate against minority voters.

Under the now-defunct preclearance formula, the law covered all of Alaska, Alabama, Arizona, Georgia, Louisiana, Mississippi, South Carolina, Texas and Virginia, and parts of California, Florida, Michigan, New Hampshire, New York, North Carolina and South Dakota.

Congress reauthorized the law, including its coverage formula, four times -- in 1970, 1975, 1982 and 2006.

Luther Strange, Alabama's attorney general, celebrated the decision in a written statement. He said he anticipated that the formula's elimination would save the state and local governments money by not having to submit preclearance applications. However, several states under the preclearance requirement, including Mississippi and North Carolina, argued just the opposite in an amicus brief -- those states said the preclearance process helped avoid expensive legal battles.

"It's like litigation paradise," said Rob Richie, executive director of FairVote, a nonprofit that advocates broader voter access and participation. Without the preclearance review by the Justice Department, "more things will have to go to court. It will be more expensive for states. What we will not have is the level of oversight on these local elections. And we should."

In the majority opinion, Roberts writes that the original preclearance formula was based on a robust body of evidence demonstrating that specific states and counties used devices, such as literacy tests, to discriminate against minority voters. In the 1960s Congress could point to low rates of voter registration and participation to demonstrate that the devices were suppressing minority voters. Thus, the preclearance was rational both in theory and in practice. "Nearly 50 years later, things have changed dramatically," he writes. Black voters register and vote in greater numbers and have more Black elected representatives than in the 1960s. To the degree that minorities still face barriers to voting in some parts of the United States, the geography has changed. The original distinctions between places that require clearance and those that do not have become outdated, he argued.

"Congress -- if it is to divide the States -- must identify those jurisdictions to be singled out on a basis that makes sense in light of current conditions," Roberts said.

In her dissent, Ginsburg writes that today’s formula does, in fact, reflect the current condition of voter discrimination. Her argument relies on research leading up to 2004 that showed states burdened with the preclearance requirement had a disproportionate share of successful Section 2 lawsuits in the previous two decades -- where courts decided that an election change was discriminatory. She also points to more than 1,000 preclearance applications between 1982 and 2006 that were either blocked or modified during Justice Department reviews.

During the oral arguments in February, Breyer acknowledged that the type of racial discrimination in elections had "evolved" and the "disease" was less prevalent. Still, several justices asked about the need for preempting what Ginsburg described as "second generation devices."

“The reason Section 5 was created was because States were moving faster than litigation permitted to catch the new forms of discriminatory practices that were being developed," Sotomayor said during the hearing. "As the courts struck down one form, the States would find another.”

Advocacy organizations that supported the preclearance formula are already shifting into campaign mode for a new formula. “We’re going to take our case very aggressively to Congress,” said Marvin Randolph, senior vice president for campaigns at the National Association for the Advancement of Colored People (NAACP). Under an updated coverage formula, “the number of states required to comply, we believe, will expand.”

Randolph said that today’s version of racial discrimination in elections takes the form of state laws shortening early voting periods, requiring photo ID to vote and restricting the voter registration periods.

“It’s clear that things have not changed as much as some folks would have you think they have,” he said. “Our opposition -- they don’t go away. They mutate.”

Experts disagreed about the long-term implications of the Supreme Court ruling. Shapiro, of the Cato Institute, said the decision was a confirmation that Jim Crow-era racial discrimination was a thing of the past. Kareem Crayton, a researcher at the University of North Carolina School of Law, said he suspects a lack of preemptive federal oversight on local elections could negatively impact minority voting. Crayton echoed concerns raised in Ginsburg's dissent about voter dilution, where a minority voter has access to the polls and can cast a ballot, but the vote has diminished influence because of a structural change, such as at-large elections.

"I suspect we'll see state and local jurisdictions trying to adopt measures that they couldn't have adopted yesterday," Crayton said.

In a written statement, President Barack Obama said he was deeply disappointed by the Supreme Court decision, which "upsets decades of well-established practices that help make sure voting is fair, especially in places where voting discrimination has been historically prevalent." He added that he was calling on Congress to pass legislation that would ensure a "fair and equal voting process."