In 1962, Bernard Lafayette Jr., a slim, erudite, 21-year-old civil rights activist with the Student Nonviolent Coordinating Committee (SNCC), was looking for a new assignment. He’d just finished exams at Nashville’s Fisk University, where he was one of a pioneering group of students who had desegregated Nashville’s lunch counters during the sit-ins and integrated interstate bus travel with the Freedom Rides. During the latter mission, Lafayette was beaten in Birmingham and arrested in Jackson, and he narrowly escaped death when his bus was attacked by white supremacists in Montgomery.

In the summer of 1962, Lafayette visited SNCC’s headquarters in Atlanta. SNCC executive secretary James Forman showed him a large map with tacks in places where the group was active. One place—Selma, Alabama—had a large X over it. SNCC had abandoned the city, Forman told Lafayette, because the organizing work was “too hard.” Only 156 of its 15,000 eligible black residents were registered to vote. “During the past decade,” writes Gary May in Bending Toward Justice, the first history of the Voting Rights Act’s passage in 1965, “only seventy-five blacks—twenty-eight of them college graduates—had tried to register, and all had failed.” Lafayette, one of the unsung heroes of the civil rights movement, departed for Selma that fall.

He encountered a city that Andrew Young, a top aide to Martin Luther King Jr., called the “most oppressive” in the South. It had been a major slave-trading port in the Black Belt and an important manufacturing center for the Confederacy during the Civil War. The city was ransacked by the Union in 1865 and occupied during Reconstruction, when Selma briefly elected black congressmen, city councilmen, county commissioners and state legislators. That era officially ended in 1901, when Alabama passed a new constitution that effectively denied black suffrage and black voter registration in the county plunged to less than 1 percent. Selma became the state headquarters of the White Citizens’ Council, known as the “KKK in suits.”

The city was ruled by a tyrannical segregationist, Sheriff Jim Clark, who fashioned himself after Gen. George S. Patton, as well as by a board of registrars that implemented a literacy test requiring black voters to name all sixty-seven county judges in Alabama in order to get on the rolls. (Most whites, of course, never faced this test.) On June 12, 1963—the same day Medgar Evers was assassinated in Mississippi—Lafayette was nearly beaten to death by white supremacists across from his home when he went to help the driver of a broken-down car. He wore the bloodstained shirt for almost a month afterward, to show the black residents of Selma not to be afraid.

Lafayette taught residents to pass the county’s literacy test and helped to organize the Dallas County Voters League, but blacks remained disenfranchised. During a Freedom Day march on October 7, 1963, when 350 African-Americans assembled at the county courthouse to register to vote, Clark’s police assaulted demonstrators in front of two Justice Department lawyers and two FBI agents, who stood idly by. Between 1963 and 1965, when Lafayette was in Selma, the Justice Department filed four lawsuits against discriminatory voting laws in the county, but the number of black registered voters increased from 156 to a mere 383.

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At the beginning of 1965, Martin Luther King Jr., fresh from being awarded the Nobel Peace Prize, arrived in Selma on the 102nd anniversary of the Emancipation Proclamation to spearhead “a determined, organized, mobilized campaign to get the right to vote everywhere in Alabama.” There were demonstrations nearly every day, but Clark and the board of registrars didn’t budge. On February 1, King and 770 others were thrown in jail. “This is Selma, Alabama,” he wrote in The New York Times from his cell. “There are more Negroes in jail with me than there are on the voting rolls.” The turning point in the fight for voting rights came on March 7, when King aide Hosea Williams and SNCC chairman John Lewis, Lafayette’s former college roommate in Nashville, led a march from Selma to Montgomery to protest the killing of unarmed civil rights activist Jimmie Lee Jackson by the police in nearby Marion.

The 600 marchers didn’t make it past Selma’s Edmund Pettus Bridge. They were brutally beaten, trampled by mounted officers, and doused in tear gas by Alabama state troopers and Clark’s vigilante posse. That evening, ABC interrupted the prime-time premiere of Judgment at Nuremberg to broadcast fifteen minutes of footage from Selma to 48 million Americans. Some viewers thought they were seeing images of Nazi Germany. There had been ample public outrage over atrocities committed against the civil rights movement—for example, when the police used dogs and fire hoses to attack children in Birmingham, or when three young men were murdered in Mississippi—but nothing had the impact of Bloody Sunday. “The Voting Rights Act would be written—in blood—on the Edmund Pettus Bridge,” May writes. Two days later, following a second aborted march led by King, a Unitarian minister named James Reeb was attacked in Selma by white segregationists when he accidentally entered the “wrong” part of town; he died shortly thereafter.

Bloody Sunday inspired sympathy marches in eighty cities, sit-ins at the Oval Office and a constant stream of demonstrators outside the White House. Eight days after Bloody Sunday, Lyndon Johnson introduced the Voting Rights Act (VRA) before a joint session of Congress. In truth, the Johnson administration had already drawn up a voting rights bill before the march, but events in Selma accelerated the president’s timetable and assured swift passage in Congress. Seventy million Americans watched LBJ’s speech. “I speak tonight,” the president said in his opening, “for the dignity of man and the destiny of democracy.” Even the most battle-scarred civil rights activists were stunned when the president invoked the movement’s mantra: “We shall overcome.”

In Selma, MLK watched the speech with Lewis, squeezed into the living room of a local dentist, fighting back tears. “We will make it from Selma to Montgomery,” King told Lewis afterward, “and the Voting Rights Act will be passed.” On the third try, they finally made it fifty-four miles from Selma to Montgomery, passing impoverished rural counties where not a single black voter had been allowed on the rolls before 1965. The march grew to 25,000 as they entered Montgomery, where King gave one of his lesser-known but most eloquent speeches, uttering the famous words that form the title of May’s book: “the arc of the moral universe is long, but it bends toward justice.” Barack Obama frequently invoked the phrase on the campaign trail in 2008.

The VRA became law on August 6, 1965, 104 years after Lincoln signed the Confiscation Act freeing Confederate slaves. “Today is a triumph for freedom as huge as any victory that has ever been won on any battlefield,” President Johnson said. He called the vote “the most powerful instrument ever devised by man for breaking down injustice.” King and Lewis, though not Lafayette or any of the other foot soldiers in Selma, were given the pens used to sign the legislation by LBJ. Lewis, now a thirteen-term congressman from King’s home district in Atlanta, keeps the pen framed in his living room and a bust of LBJ in his Washington office. In his excellent memoir Walking With the Wind, Lewis called the day “a high point in modern America, probably the nation’s finest hour in terms of civil rights.”

The VRA quickly became regarded as one of the most transformative pieces of legislation ever passed by Congress. It suspended literacy tests across the South, authorized the attorney general to file lawsuits challenging the poll tax, replaced recalcitrant registrars with federal examiners, forced states with a history of voting discrimination to clear electoral changes with the federal government to prevent future discrimination, and laid the foundation for generations of minority elected officials, including Obama. In 1965, there were fewer than 500 black elected officials nationwide. Today, there are more than 10,500.

The law had an immediate impact. On August 10, federal examiners from the Civil Service Commission arrived in Selma and other centers of hard-core resistance to begin registering black voters. During the next year, the number of black voters in Dallas County increased from 400 to more than 10,000. The 1966 primary elections in Alabama were the first test of the new law. Selma’s moderate commissioner of public safety, Wilson Baker, challenged Clark for sheriff. Baker courted black voters, while Clark appealed to his segregationist base. Baker accumulated a comfortable lead thanks to the large black turnout, but the Dallas County Democratic executive committee, which supported Clark, refused to count six boxes of ballots from predominantly black precincts that would have given Baker a large enough margin of victory to avoid a runoff. Assistant Attorney General John Doar immediately filed a lawsuit in federal court asking that the votes be counted. Judge Daniel Thomas of Mobile ruled for the government, and that November Selma elected a new sheriff. Though it would take much longer for blacks to gain real representation in the South (Selma didn’t elect a black mayor until 2000), the election and its aftermath were a preview of the changes to come.

The temporary provisions of the VRA were overwhelmingly reauthorized by Congress four times in subsequent years and strengthened every time. Critics of the law had no choice but to acknowledge its popularity. “Even the name of it is wonderful: the Voting Rights Act,” Justice Antonin Scalia said in February. “Who is going to vote against that in the future?”

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Given the magnitude of the VRA, it’s surprising that it took forty-eight years for someone to chronicle the law’s passage. May, a professor of history at the University of Delaware, has written about the subject before in a biography of Viola Liuzzo, a Detroit housewife killed by members of the KKK following the climactic Selma-to-Montgomery march. Parts of May’s narrative, particularly the first few chapters, will be familiar to students of civil rights history, chronicled previously in books like David Garrow’s Protest at Selma (1978) and Steven Lawson’s Black Ballots (1976) and In Pursuit of Power (1985). But May’s book is a great introduction to voting rights at a moment when the subject is drawing more attention than any time since 1965.

Bending Toward Justice was published in April, two months before the Supreme Court—with Scalia in the majority—invalidated the centerpiece of the VRA, Section 4, the formula designating that states with the highest frequency of voting discrimination (primarily in the South) had to approve their voting changes with the feds. Section 5, the preclearance position, still theoretically exists, but it is now a zombie rule because it no longer applies to states. Justice Ginsburg cited May’s book in her scathing dissent in Shelby County v. Holder, noting that Shelby County, Alabama, which challenged the VRA’s constitutionality, committed the very type of voting discrimination that Section 5 was designed to stop: in 2008, the city of Calera eliminated its only majority-black city council district. The change was invalidated—and new districts drawn—only after the Justice Department stepped in. Now Shelby County and so much of the South are free to return to their old ways.

Chief Justice John Roberts based his decision on what he called the “fundamental principle of equal sovereignty” among the states, which he ruled Section 4 violated by treating some states differently from others. That argument is eerily reminiscent of those made by South Carolina, Alabama, Louisiana, Mississippi and Virginia when they first challenged the VRA’s constitutionality in 1965—an argument the Supreme Court of that day soundly rejected. “We here hold that the portions of the Voting Rights Act properly before us are a valid means for carrying out the commands of the Fifteenth Amendment,” wrote Chief Justice Earl Warren in an 8–1 opinion in South Carolina v. Katzenbach. “Hopefully, millions of non-white Americans will now be able to participate for the first time on an equal basis in the government under which they live.”

The strongest parts of May’s book are his descriptions of the fight for voting rights from 1963 to 1965 in places like Selma and his detailed account of the VRA’s passage, to which he devotes six of his nine chapters. The last third of the book, which chronicles the persistent attempts to weaken the VRA during the Nixon and Reagan years and the resurrection of voter suppression efforts following Obama’s election, seems somewhat hastily put together. What happened after 1965—the flipping of the South from Democratic to Republican, the conservative counterrevolution against voting rights, the rise of minority voting power—still remains a deeply underreported current of contemporary American history.

One could argue persuasively that the George Wallaces and Richard Nixons of America lost many civil rights battles, but ultimately won the war. The Reagan revolution of the 1980s ushered in a new generation of conservative legal activists, among them John Roberts, who used the power of the courts to blunt the achievements of the 1960s civil rights movement. As a 27-year-old special assistant to Attorney General William French Smith, Roberts waged an energetic campaign against Section 2 of the VRA, a nationwide prohibition on racial discrimination. “Violations of Section 2 should not be made too easy to prove,” Roberts wrote, arguing that this would “establish a quota system” for minority elected officials and “provide a basis for the most intrusive interference imaginable by federal courts into state and local processes.” Congress overruled Roberts when it reauthorized the VRA in 1982, but Roberts got his revenge three decades later as chief justice. His mission on the Court, The New Yorker’s Jeffrey Toobin has written, is “to declare victory in the nation’s fight against racial discrimination and then to disable the weapons with which that struggle was won.”

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The VRA’s passage in 1965 was due to a number of unique factors: the denial of voting rights in the South for nearly ninety years following the end of Reconstruction; an unyielding and unspeakably brave civil rights movement; profound public outrage about the violence in Selma; the most liberal Congress since the New Deal; a Republican Party filled with Northern moderates, many of them senior figures; and, in LBJ, a president who’d just been elected by the largest margin of victory in presidential history, who cared deeply about civil rights (although for much of his career didn’t show it), and who knew how to steer complex legislation through Congress.

Few of these crucial elements are present today, despite having a black president in the White House, which is why many are pessimistic that an updated VRA can be shepherded through Congress. The final draft of the VRA, May reminds us, emerged from the office of Senate minority leader Everett Dirksen, Republican of Illinois. Also working out of the Senate, Bob Dole, Republican of Kansas, brokered the compromise agreement that secured an extension of the VRA in 1982. “It is hard to see John Boehner, the current Republican Speaker of the House, or Mitch McConnell, the Senate Republican Leader, playing similar roles,” May wrote several months ago in Salon.

Indeed, today the VRA looks like a classic victim of its own success. In his opinion in Shelby County v. Holder, Roberts cited the progress made on civil rights since 1965, much of it owing to the VRA, but conveniently ignored the widespread attacks on voting rights following the 2010 election. “Just when it seemed that the democratic process had reached its apotheosis with the election of America’s first black president,” May writes, “a political earthquake occurred in 2010 that threatened all that had been accomplished since 1965.”

From 2011 to 2012, 180 new voting restrictions were introduced by Republicans in forty-one states and passed in key battlegrounds like Ohio, Florida, Pennsylvania and Wisconsin under the guise of stopping “voter fraud.” Though many of these laws were temporarily blocked in court during the last election, including under Section 5, the push to curb voting rights has accelerated since the Supreme Court’s decision, with seven Southern states passing or implementing new voting restrictions that disproportionately impact people of color. Voting changes blocked by the federal courts as discriminatory as recently as last summer, like Texas’ voter ID law, will now go into effect, while North Carolina recently adopted an election law that Hillary Clinton aptly described as “the greatest hits of voter suppression.” It will take a new iteration of the civil rights movement to win the battle against Jim Crow II.

This country has many distinctions as a democracy. The saddest is that it is the only advanced democracy ever to disenfranchise, enfranchise and disenfranchise again an entire segment of the population. What should be its most settled right—the right to vote—remains the most contested. Our past tells us that people don’t recognize how important that right is until it’s taken away.