The eight men knew the next step they took would not only change their lives, it could possibly end them as well. “You will take one step forward as your name and service are called and such step will constitute your induction into the Armed Forces indicated,” Lieutenant Steven Dunkley instructed the draftees standing before him inside the Armed Forces Examining and Entrance Station in Houston, Texas, on April 28, 1967.

As Dunkley called out the first six names from a stack of cards, the draftees stepped forward one-by-one to join a military deep in the throes of the Vietnam War. The lieutenant then cried out, “Muhammad Ali, would you please step forward!” The kinetic feet of the reigning heavyweight boxing champion that constantly shuffled around ring rivals remained perfectly still at the request. Dunkley then called out the champ’s birth name, “Cassius Clay!” The 25-year-old remained tethered to the floor as the lieutenant called out both names twice more.

While the other seven draftees left by a back door to board a bus to begin basic training at Louisiana’s Fort Polk, Ali walked out the front door of the induction station to face a crush of reporters and await the consequences.

If there was one thing Ali could do better than box, it was talk, and his outspokenness put him at the center of countless arguments about race, religion, politics and war during the turbulent 1960s, particularly after he confirmed his conversion to the Nation of Islam the morning after he defeated Sonny Liston in 1964 to capture the heavyweight belt. Ali cited his religious beliefs against war as the reason he should be exempt from joining the 438,000 American troops in Vietnam. “I am a member of the Muslims and we don’t go to no wars unless they are declared by Allah himself,” Ali told Chicago Daily News sportswriter Tom Fitzpatrick.

“When he first filed for a draft exemption, it was as a conscientious objector. Then Ali found out that if you got the conscientious objector status, you could still be drafted and required to do non-combat services,” says Leigh Montville, author of the new book “Sting Like a Bee: Muhammad Ali vs. the United States of America, 1966-1971.”

Ali sought the advice of attorney Hayden Covington, who had successfully represented Jehovah’s Witnesses against draft boards. “He was the most successful lawyer ever to go against the Supreme Court at the time,” Montville tells HISTORY. “Covington’s success with the Jehovah’s Witnesses was based on the contention that everyone who was a member was a minister, and the Jehovah’s Witnesses were historically a very active religious group, ringing doorbells and proselytizing. Covington tried to make a case that Ali was a minster like that, and he was in a way because he spoke at temples and was always talking about his religion.”

Ali’s request for an exemption because he was a minister was not an unusual one. More than 100,000 Americans including ordained ministers, seminarians and divinity students had already received 4-D exemptions—nearly five times as many who had been designated as conscientious objectors.

Inside the ring, Ali emulated the theatrics of the noted wrestling heel Gorgeous George, and his controversial comments about the Vietnam War—“I don’t have no personal quarrel with those Viet Congs,” he told Fitzpatrick—were making him a villain outside of the ropes as well in the eyes of millions of Americans, particularly those who had served in World War II. “In 1967, the country is still pro-Vietnam War. It’s still ‘my country right or wrong.’ The numbers after that start to become grim and the results few, so 1967 was probably the crest of public support for the Vietnam War,” Montville says.

“I’m not going 10,000 miles from home to help murder and burn another poor nation simply to continue the domination of white slave masters of the darker people the world over,” Ali said a week before his scheduled induction ceremony. “If I thought the war was going to bring freedom and equality to 22 million of my people, they wouldn’t have to draft me, I’d join tomorrow.”

Less than two months after Ali refused to step forward at the induction center, an all-white jury took just 21 minutes to find him guilty of draft evasion on June 20, 1967. The judge made an example of the high-profile defendant by handing down the maximum penalty for the felony offense—five years in jail and a $10,000 fine. “It is too bad he went wrong. He had the makings of a national hero,” lamented Washington Post columnist Shirley Povich. The New York Athletic Commission revoked the champ’s boxing license while the World Boxing Association did what none of Ali’s professional opponents had been able to do up to that point in stripping him of his title.

Released on bail pending appeal, Ali lived for three years in exile from the ring. As public opinion began to turn against the war, however, it softened against Ali. In 1970 the New York State Supreme Court ordered his boxing license reinstated, and the following year the U.S. Supreme Court overturned his conviction in a unanimous decision. After 43 months away, Ali returned to the ring on October 26, 1970, and knocked out Jerry Quarry in the third round. Four years later, he regained the heavyweight belt after knocking out George Foreman in the “Rumble in the Jungle.”

“It’s interesting in how it all ended with the Supreme Court. Basically they just gave him a pass for being Muhammad Ali. If he had been a normal guy he would have been in jail two years before. In the end it was celebrity justice,” Montville says. “In the beginning he was penalized for being Muhammad Ali and in the end was let off for being Muhammad Ali, which probably shows you the course of the Vietnam War right there that one guy saying the one same thing is interpreted two different ways in a matter of years.”

“As more American kids come back in boxes, the whole view of the war changes. By the time he does get his license back, the hatred is pretty much muted,” Montville says. “It’s an interesting proposition about whether his story and career would resonate with people the way it does now without the draft episode—and it wouldn’t. It was what made him an international celebrity.”