But Ali had been convicted in 1967 and sentenced to 5 years in prison. The Supreme Court case that ultimately kept him out of prison came in 1971. What did the Court decide? Here's the very unusual inside story, found in "The Brethren" by Bob Woodward and Scott Armstrong:
Apart from the complicated war and draft issues, there were racial overtones to the case.... Public sympathy was growing for Ali, but at the same time the Black Muslim faith had been portrayed as separatist, antiwhite and bizarre....In the conference after the oral argument, the judges voted 5 to 3 in favor of the government — because you have to oppose all war to qualify as a conscientious objector — and Justice Harlan was assigned to write the case. (The 9th justice was Thurgood Marshall, "recused because he had been Solicitor General when the case began.")
Given Ali’s prominence, the Justices would allow him the satisfaction of having his case reviewed by the highest court in the land, a satisfaction given to few defendants. None of the Justices believed Ali had a chance of winning.
At oral argument, Solicitor General Griswold pointed out that Ali had left little doubt that “if the Vietcong were attacking his people, the Muslims would become involved in that war.” Moreover, Ali had been quoted in the press as saying, “I am a member of the Muslims and we don’t go to war unless they are declared by Allah himself. I don’t have no personal quarrel with those Vietcongs.” Since Ali would participate in a holy war, he was not really a conscientious objector, Griswold said.
But as Harlan’s clerk began preparing a draft opinion, he was persuaded by another clerk who had read Alex Haley’s Autobiography of Malcolm X to reconsider the question of Ali’s opposition to war. Reading the Message to the Black Man, one of the most trusted texts of the Black Muslims, the clerk became convinced that Ali’s willingness to fight in a holy war was irrelevant. For all practical purposes, Ali was opposed to all wars.Harlan was nearly blind.
Harlan was not inclined to buy any of this. But he agreed to take home his clerk’s background materials and study them in the specially illuminated library of his Georgetown townhouse.
The next morning, he had a surprise for his clerks. He had read the materials and he agreed wholeheartedly, wanting them incorporated, as written, into his draft. Harlan was persuaded that the government had mistakenly painted Ali as a racist, misinterpreting the doctrine of the Black Muslims despite the Justice Department’s own hearing examiner’s finding that Ali was sincerely opposed to all wars.Harlan switched sides, and his opinion didn't convince the others who'd sided with the government. (These were Chief Justice Warren Burger and Justices Black, White, and Blackmun.) They didn't like any of that, especially what looked like groundwork for all Black Muslims to claim conscientious objector status. So the vote at that point was at 4 to 4, which would leave the result from the court below in place and would have sent Ali to prison for draft evasion. There wouldn't even be an opinion explaining why, and this bothered Justice Stewart, who "proposed an alternative: the Court could simply set Ali free, citing a technical error by the Justice Department." Unlike Harlan's opinion, it set no precedent that anyone else would be able to use.
Harlan wanted to confront the Justice Department’s misrepresentation and state explicitly that there had been “no basis in fact” all along for them to say that Ali was not really opposed to all shooting wars. Because there had been no indication outside Harlan’s chambers that his view had changed, when his memo suggesting reversal of the conviction was circulated, it exploded in the Court. Burger was beside himself. How could Harlan shift sides without notifying him? He was even more irritated by the incorporation of Black Muslim doctrine in the opinion. The draft said that Black Muslim doctrine teaches “that Islam is the religion of peace …and that war-making is the habit of the race of devils [whites] … [and that Islam] forbids its members to carry arms or weapons of any kind.” Harlan had become an apologist for the Black Muslims, Burger told a clerk.
Gradually, all but the Chief agreed to go along with Stewart’s plan.... That left Burger with a problem. If he dissented, it might be interpreted as a racist vote. He decided to join the others. An 8-to-0 decision would be a good lift for black people, he concluded.