Amid all the paeans to the memory of the Rev. Martin Luther King Jr. that will be published today, it’s vital to note that at this moment perhaps his most important legacy — his struggle to ensure the full realization of voting rights for all Americans — is under greater threat than at any time since his death.

King, who would have turned 90 this year, was a tireless advocate for freedom, equality and democracy. He urged the nation to revitalize the amendments added to the Constitution after the Civil War — what he called the “full pledge of freedom” — to ensure equal citizenship for all. Even as a teenager, he spoke eloquently for the “13 million black sons and daughters of our forefathers” who “continue the fight for the translation of the 13th, 14th and 15th amendments from writing on the printed page to an actuality.”

At the center of King’s campaign for freedom was ending racial discrimination in voting. Over the course of his life, he demanded, time and again, “give us the ballot.” The right to vote was a core fundamental right: “To deny a person the right to exercise his political freedom at the polls is no less a dastardly act as to deny a Christian the right to petition God in prayer.”

King denounced the many types of “conniving methods” that were “still being used to prevent” African Americans from exercising their franchise. “The denial of this sacred right,” he insisted, was a “tragic betrayal of the highest mandates of our democratic tradition.” King led one of the greatest marches in American history — from Selma, Ala., to the state capital in Montgomery — to demand that Congress end the “flagrant denial of the right to vote.”

Today, the Voting Rights Act that King helped to push through Congress is in tatters. To stop voting discrimination, the Voting Rights Act created strong remedies applicable to jurisdictions with a long history of flouting constitutional guarantees. Such jurisdictions would have to “preclear” new voting changes and prove they were nondiscriminatory before enforcing them. In 2013, in a 5-4 ruling in Shelby County v. Holder, the Supreme Court eliminated this critical remedy. Claiming that things had changed, Chief Justice John G. Roberts Jr. insisted that the Voting Rights Act’s coverage formula was now unconstitutional.

In Shelby County, the Supreme Court’s conservative majority ignored that the Constitution gives Congress sweeping powers to stamp out racial discrimination in voting. Turning a blind eye to the Constitution’s text and history, the court gutted our nation’s most successful tool to curb voting discrimination.

Our democracy hasn’t been the same since. In 2018, as in past years, voter suppression ran rife. As they had in King’s day, states resorted to new methods to keep African Americans and other voters from the polls. States invented new roadblocks to voter registration, aggressively purged citizens from the voting rolls, closed hundreds of polling places in areas where voters of color reside, and imposed new, stricter voter identification laws that disenfranchised minority and other voters for no good reason. In Georgia and elsewhere, as Democratic gubernatorial candidate Stacey Abrams put it, “democracy failed.”

The 2018 elections offered fresh evidence of why restoring the Voting Rights Act is critical to restoring our democracy. From 1965 to 2013, preclearance worked because it stopped voting discrimination in its tracks. But, in 2018, without the full protection of the Voting Rights Act, discriminatory voting changes were enforced and made it harder for voters of color to cast a ballot.

Time and again, when voters went to court, they were often turned away. Courts refused to redress voter suppression, insisting that it was too late to do anything about it. Even in cases of flagrant voting discrimination — such as Kansas’s suspicious decision to move out of town the only polling place from Dodge City, a town with a Hispanic majority — the courthouse doors were bolted shut.

Congress has an opportunity to right these wrongs. It should start by writing a new coverage formula that captures the jurisdictions that, year in and year out, flout our Constitution’s promise of equal political opportunity for all, regardless of race.

Revitalizing the Voting Rights Act — the crown jewel of the civil rights movement — would be a fitting way to honor King’s remarkable legacy.