The civil-rights movement has been richly chronicled in books like Taylor Branch’s trilogy on Martin Luther King Jr. and documentaries like Eyes on the Prize. But there have been few equally powerful depictions of the movement in pop culture, which tend to overstate the contribution of white protagonists and turn African-Americans into supporting players in their own struggle (i.e., The Help, Mississippi Burning etc).

That’s why the new film Selma is such an important work.

The movie is unique in many respects. It movingly captures the dramatic events that led to the passage of the Voting Rights Act of 1965. It has a great cast, anchored by an unusually nuanced portrayal of King by David Oyelowo. It also boasts a diversity rarely seen in major films, both on screen and behind the camera: as a black woman filmmaker, writer-director Ava DuVernay is, sadly, a rarity in Hollywood. In her hands, Selma skillfully shows the tensions within the civil-rights movement between groups like King’s Southern Christian Leadership Conference and the young activists with the Student Nonviolent Coordinating Committee, and the many pressures—personal, political and organizational—that King faced at the time.

Despite glowing reviews, the film has attracted controversy for its portrayal of Lyndon Johnson. Some of this criticism is the result of an Oscar-season smear campaign and former aides to the president who are over-protective of his legacy. But as an admirer of the film and DuVernay, I must confess that I found the depiction of Johnson to be unnecessarily one-sided, and out of sync with the history I’ve extensively studied in the course of writing a book on the history of voting rights since 1965.

Selma depicts King as a crusader for voting rights and LBJ, in contrast, as a voting rights skeptic. The reality is more complex, and gets to the heart of how the VRA came to be.

One of the first scenes in the film shows King meeting with the president in the Oval Office on December 18, 1964, eight days after King won the Nobel Peace Prize. He urges Johnson to take up voting rights legislation to end the systematic disenfranchisement of African-Americans in the South. “Let’s not start another battle until we’ve won the first,” Johnson tells King in the film, referring to the passage of the Civil Rights Act of 1964. “This voting thing is just going to have to wait.” After the meeting, King tells Andrew Young they’re going to Selma to launch a voting-rights campaign.

In real life, LBJ did tell King something to that effect at that meeting, saying he wanted to focus on Great Society legislation in 1965, and that voting-rights legislation couldn’t pass Congress so soon after the enactment of the Civil Rights Act. “I’m going to do it eventually, but I can’t get voting rights through in this session of Congress,” LBJ told King, according to Nick Kotz’s great book Judgment Days: Lyndon Baines Johnson, Martin Luther King Jr., and the Laws That Changed America.

What Selma doesn’t show is that four days before meeting with King, LBJ told his acting attorney general Nicholas Katzenbach to begin drafting a voting-rights bill. “I basically believe that we can have a simple, effective method of gettin’ ’em registered,” the president said. “Just get me some things you’d be proud of, to show your boy, and say, ‘Here is what your daddy put through in nineteen sixty-four, -five, -six, -seven.’ ” LBJ was a notorious wheeler-dealer who liked to keep his options open, which is why he told King one thing and Katzenbach another. Two weeks later, Katzenbach sent LBJ three options for a voting-rights bill.

On January 15, 1965, after King had arrived in Selma, Johnson called the civil-rights leader on his birthday. “We have got to come up with [voting-rights legislation],” Johnson told him. “That will answer 70 percent of your problems!” He urged King to highlight examples of blacks being denied the right to vote, which was the purpose of King’s campaign in Selma.

While King and civil-rights activists bravely tried to register black voters in Selma, the Civil Rights Division of the Justice Department was busy drafting voting-rights legislation. Two days before the Bloody Sunday march, DOJ lawyers finished a rough draft of a voting-rights bill, giving the federal government extensive power over voter registration in the South.

The violent response to the protests in Selma significantly accelerated the administration’s timetable for pushing voting-rights legislation—LBJ’s aides were previously divided on what the bill should look like, when to introduce it and how aggressively to promote it—and compelled Congress to act swiftly. “The climate of public opinion throughout the nation has so changed because of the Alabama outrages, as to make assured passage of this solid bill—a bill that would have been inconceivable a year ago,” House Judiciary Committee Chairman Emanuel Celler said on March 18, 1965, when the House began hearings on the VRA.

In another scene in Selma, King is shown lecturing LBJ about the need for a voting-rights bill following the death of the white minister James Reeb in Selma, who was brutally beaten by white segregationists following a second aborted march from Selma to Montgomery on March 9. When I saw the film, audience members cheered as King put Johnson in his place. But Johnson didn’t need to be converted at that point; his administration was frantically trying to finalize voting-rights legislation that week.

Johnson championed the Voting Rights Act in a dramatic speech before a joint session of Congress on March 15, which is shown in the film, and his administration skillfully shepherded the bill through Congress, defanging Southern opposition. The result was the most impactful civil-rights legislation of the twentieth century.

At a signing ceremony at the US Capitol, LBJ gave King one of the pens he used to sign the VRA. “You have created a Second Emancipation,” King told the president. It took King’s activism and LBJ’s leadership to get it done.

Why does this matter today?

“When it comes to voting rights, you realize the past isn’t the past,” former NAACP president Ben Jealous once told me. Selma comes out at a time when the VRA is under attack like never before and states are enacting the most significant restrictions on voting rights since the end of Reconstruction. “If there is anything that we should be talking about in terms of legacy, it is really the destruction of the legacy of the Voting Rights Act,” DuVernay said recently.

To protect voting rights today, we must understand how those rights were secured in the past. It requires determined activists who can dramatize the inequities in our democracy and political leaders who can channel the movement’s goals. We have neither a King nor an LBJ today.