Marijuana’s moment finally seems to be here. At Hempfest in Seattle last month more than 100,000 fans rallied for the one-time evil weed. The governor of New York State and the mayor of Chicago recently supported the repeal of criminal penalties against a personal stash. And next month, if current polls hold, voters in Colorado and Washington will approve historic measures that make the pot nearly as legal as heirloom tomatoes. “This is clearly the tipping point,” says Keith Stroup, the grand old soul of the legalization movement. “We are in the process of ending marijuana prohibition in America,” he tells me.

But hold on a minute. The last time the movement was this cocky it was dead within six months, murdered by some of its own best friends. These included Jimmy Carter’s reform-minded drug czar, staffers at High Times magazine, and, yes, Keith Stroup himself, who did more than most to bring pot smokers into the mainstream—and more than most to send them back to the wings.

To find out if it could all go sideways again, I asked Stroup to do something he’s never done before: revisit the scene of the wildest, saddest chapter in the long fight for more liberal drug laws. That meant trying to find the house where the forces of change last came together—almost exactly 35 years ago—only to vanish up someone’s nose. To his immense credit, Keith Stroup was game.

“I want to say it’s the next block,” he says, striding down S Street in Washington, D.C. At 68 years old, and an almost daily marijuana user for decades, Stroup and his trademark energy has yet to flag. Block after block, we’re still walking, until finally he stops in front of a four-story cream-colored townhouse. “That would be the one,” he says, running a hand through his collar-length gray hair, although it’s clear he isn’t totally sure. “It’s awfully big.”

It had to be big. In the late 1970s, the movement itself was big, growing from a disorganized band of freaks into an upright national coalition for smokers’ rights—with Stroup as Pied Piper. Raised by God-fearing squirrel-hunting conservatives in southern Illinois in the 1950s, he jumped from the University of Illinois to Georgetown Law School to Ralph Nader’s Product Safety Commission, discovering pot and politics in the process. In 1970 he launched the National Organization for the Reform of Marijuana Laws, or NORML—perhaps the world’s first lobby for the openly criminal.

NORML seemed like quixotic kids’ stuff at first. While the adults declared War on Drugs and handed out quarter-century prison terms to pot smokers, what could a few long-hairs with law degrees do? At the start, just a sliver of the country supported a softer approach to pot. But by 1976 the kids were winning. NORML’s legal program shaved decades off of the prison terms of pot smokers, and its lobbying arm provided coast-to-coast leadership, ultimately helping eleven states decriminalize simple possession. And yet the highest high was still ahead.

Reading the smoke signals emanating from young America, Jimmy Carter campaigned on the promise of decriminalizing marijuana. When he won, he brought the reform movement into the White House and his staff brought Keith Stroup in from the margins. The man who had partied with pot smugglers and Playboy bunnies was now a privileged insider, a friend of 1600 Pennsylvania Avenue, working alongside administration officials to end all criminal penalties for possession of up to an ounce of marijuana. “Penalties against drug use should not be more damaging to an individual than the use of the drug itself,” Carter told Congress in 1977, using a line Stroup personally helped craft with one of the president’s speechwriters.

A Gallup poll showed that a clear majority of the country agreed that pot should be decriminalized. That same year, the Senate Judiciary Committee voted to support a bill that would do just that. And Stroup publicly predicted the end of all federal prohibition by 1980. “Smokers were finally out of the closet,” former Carter adviser Robert Carr reflected a few years later. “There was a sense of celebration.”

Enter the large, cream-colored townhouse: the perfect setting for NORML’s 1977 Christmas party, a gathering that makes today’s Hempfest rallies seem like fringe events by comparison. On the night of the party, more than 300 young Washington Somebodies poured into the mansion, where a psychedelic juggler tossed strobe lights and silver trays circulated with caviar and hand-rolled joints of the finest Southern-grown herb. But the party was most notable because of a single guest: Peter Bourne, the self-described “first drug czar,” the first person to be given authority over both the treatment and law enforcement sides of federal policy.

Bourne was Stroup’s closest federal ally, the only senior drug policy official ever to back decriminalization. He was also a friend. When Stroup was tangled up on drug charges in Canada earlier that year, Bourne says he wrote a letter to the authorities, helping the young lawyer hold onto to his right to practice law. Now, inside the cream-colored townhouse, before a stunned circle of partygoers—including High Times staffers and the drug scene poet laureate, Hunter S. Thompson—the unimaginable happened: America’s top drug warrior joined America’s top drug lobbyist for two lines of cocaine, according to Patrick Anderson’s 1981 book High in America, the story of Stroup’s rise and fall. Afterwards, Anderson continues, Thompson threw his arm around a writer for High Times, sighed loudly, and declared, “My God, man, we’ll all be indicted.”

Although there were at least five journalists in the room, the story held for almost six months. It might have held forever, but Bourne, a psychiatrist, came under scrutiny for writing a comely female assistant a Quaalude prescription under a false name. There was an honest explanation, but the press went for the twofer. To confirm the cocaine story, a reporter called the last people you would expect to tell on another drug user: two staffers from High Times, who have never been identified—and Keith Stroup. Since the party, Stroup had soured on Bourne for his support of spraying Mexico’s marijuana crops with a dangerous pesticide. Stroup says he was also doing a lot of cocaine at the time and “not thinking strategically.”

He confirmed the story: Drug Czar Does Cocaine at Pot Party. It broke on Good Morning America. Bourne has always denied actually doing anything more than “good old American whiskey” at the party, but it didn’t matter. He had been there and that was enough—he resigned within 36 hours, taking the marijuana reform movement with him. “The departure of Peter Bourne from the White House marked the beginning of the end of any kind of enlightened drug policy in America,” according to Carr, the Carter adviser. Said another participant, “It vanished up Peter Bourne’s nose.”

Peter Bourne tends to agree, the disappointment apparent in his voice. In his first interview on the subject in 12 years, he told The Daily Beast that decriminalization “probably” would have happened if his tenure had not been cut short. “We were actually fairly close,” he says by phone from England, where he is a senior research fellow at Green Templeton College at the University of Oxford. Dealing would still be illegal, and states would have been free to maintain their own harsher penalties, regardless of federal policy. But Bourne believes “a lot of states” would have followed him.

Instead, the Bourne incident killed drug reform as a winning issue for Carter and crippled NORML; for his perfidy, Stroup himself was forced to resign. “I felt like a failure,” he says. “If I had not been enjoying cocaine in those years, I certainly would not have been so foolish as to go upstairs with the president’s drug adviser and snort cocaine with a dozen other people,” he says. “Jeez. When the first person came up and said Peter wants to do a line, I should have said, you’re out of your fucking mind. Not here. But instead I was thinking, I want to make our relationship even tighter and doing illegal drugs together is kind of a communion.” Later, he reprises a line he has used before: “It was probably the stupidest thing I ever did. (“He’s probably right,” Bourne quips.)

If history were weighted evenly, Stroup would always be remembered as a heroic crusader who defended the average pot smoker, first articulated a vision of legal weed in America—and then did more than most to tilt people in his direction. Many already hold this image. They stand and clap when he appears on stage, and pump his hand at parties. But history is not fair, and many others see Stroup as the rat who ruined everybody’s high.

That’s a shame. You don’t have to go further than the NORML offices—located across the street from the St. Regis Hotel, around the corner from the American Legion headquarters, in a modern building less than two blocks from the White House—to see how far Stroup has pushed pot into the mainstream. When NORML opened its doors fewer than one in five Americans supported full-blown legalization (as opposed to decriminalization, which still entails fines and prohibitions on selling); today a majority of Americans do. And Stroup, who returned to head NORML between 1994 and 2005 and whose memoir, Living NORML, will soon be published by High Times books, is predicting another wave of major reforms. “In four or five years I doubt we’ll be arresting marijuana smokers in America, period,” he says, “and I think you’ll have four or five states with legal, regulated models.”

But this generation’s reform movement is still plagued by infighting. It helped doom California’s 2010 effort and threatens to undermine similar ones in Colorado and Washington this year. Some reformers want an absolutely unrestricted marijuana market, treating it like tomatoes or parsley; others want an alcohol model; still others prefer an expansion of the medical model to encompass everyone, so rest and relaxation might qualify for a prescription. “Bullshit,” Stroup says of this final idea. But he quickly adds that such squabbling is stupid. “Terribly short-sighted.” he says. “The result of being too close to the action to see the big picture.”

Stroup certainly sees it now. As we walk away from the house where the marijuana movement last peaked, Stroup ever so slightly brightens. It’s clear he believes a new high is coming his way, ever optimistic that this year really will be the one. “It’s great to be alive,” he says. “This is the most exciting moment in the 40 years I’ve been working on the issue.” And that’s saying something.