Nancy Wiechec / Reuters

The late Irving Feiner would have made a hell of a lawyer. After he spoke to my First Amendment class twenty years ago, a few students suggested he’d also have been a better professor than I. Professor Ralph Stein of Pace Law School told a newspaper that, after Feiner lectured to his class, “he had trouble leaving the class because the students kept talking to him. They would ask him to autograph their casebooks.”

But Feiner is the name of a landmark case rather than of a distinguished civil-liberties lawyer. That’s a shame—one that can be laid at the feet of the United States Supreme Court, which in 1951 affirmed Feiner’s state-court conviction for disorderly conduct. Feiner was expelled from Syracuse University, and his multiple admissions to law school were rescinded. He spent the rest of his life as a dealer in tropical fish—and as a civil-rights advocate and political activist (he helped form the Working Families Party, among other things). He died in 2009 in Valhalla, New York.

Feiner’s life changed on March 8, 1949, when he mounted a wooden box at a busy Syracuse street corner to invite passersby to a meeting in support of the Trenton Six—six African American defendants who had been convicted in 1948 by an all-white jury of the murder of a shopkeeper. (Eventually, four of the six went free after appeal; two were convicted.) The rally had been scheduled for a public-school auditorium that night; at the last minute, the mayor had canceled the event, requiring a quick change of venue to a nearby hotel. Feiner was trying to get the word out. Accounts differ about what he said: The police later claimed he urged African American listeners to “rise in arms,” while Feiner recalled saying that blacks and whites should protest “arm in arm.”

But what’s clear is that some white onlookers took offense, and one of them told a police officer, “If you don’t get that son of a bitch off, I will go over and get him off there myself.” The police told Feiner to shut up and come down; when he refused, they arrested him.

Writing for a six-justice majority, Chief Justice Fred Vinson accepted the lower court’s version of events without question. “[W]hen as here the speaker passes the bounds of argument or persuasion and undertakes incitement to riot,” he wrote, the police had every right to “prevent a breach of the peace.” Justices Hugo Black and William O. Douglas both dissented, sharply. The police had made no attempt to protect Feiner, they noted, and the evidence did not support a charge of “incitement to riot.” But Feiner’s conviction, his expulsion, and the rescission of his law-school admissions stood.

Feiner v. New York, never overruled, shambles around the legal landscape like a First Amendment zombie. When Southern sheriffs in the 1960s used the “danger” of mob action to break up civil-rights demonstrations, the Court refused to accept their claims. Instead, the Court fashioned an important principle—courts hearing a First Amendment claim may not just accept the conclusions of courts below; they must re-examine the factual record to see whether there really was a threat of disorder.

The en banc majority of the Sixth Circuit did exactly that last week in a case called Bible Believers v. Wayne Co. Overruling both a district judge and a three-judge appeals panel, the majority held that the Wayne County sheriff’s deputies could have—and thus should have—protected the First Amendment rights of fundamentalist Christian demonstrators who invaded the 2012 Arab International Festival in Dearborn. The demonstrators held signs deriding Muhammad (“child molesting pervert”) and Islam (“a religion of blood and murder”). They also carried the severed head of a pig on a stick, supposedly as protection from Muslims, to whom pork, and pigs, are unclean.

Angry teenagers began pelting them with plastic bottles, garbage, rocks, and a milk crate. The sheriff’s deputies detained a few of the rock-throwers; but soon they told the Believers to leave or face citation for disorderly conduct. Examining the record independently, the en banc majority concluded that the sheriff’s office had enough officers on hand to protect the Bible Believers, and should have done so:

The Bible Believers attended the Festival to exercise their First Amendment rights and spread their religious message. The way they conveyed their message may have been vile and offensive to most every person who believes in the right of their fellow citizens to practice the faith of his or her choosing; nonetheless, they had every right to espouse their views ... When the message was ill-received, the police did next to nothing to protect the Bible Believers or to contain the lawlessness of the hecklers in the crowd. Instead, [they] accused the Bible Believers of being disorderly and removed them from the Festival. On this record, there can be no reasonable dispute that the [sheriff’s office] effectuated a heckler’s veto, thereby violating the Bible Believers’ First Amendment rights.

Bible Believers displays vividly the underlying strength of the American commitment to free speech—and the troubling shadow that commitment inevitably casts.

Only a few things that public speakers say can be punished. “Islam is bad” isn’t one of them, even when said to a large, angry crowd of Muslims. A speaker who said, “Kill some Muslims now!” could be punished for incitement. A speaker who said to a specific person, “You are a disgusting infidel and your religion stinks and you are going to hell” might be punished for “fighting words.” A speaker who brandishes a pig’s head—or any other object—to convey a physical threat can be punished as well.

Otherwise, police can’t arrest a speaker for saying something awful.

The civil-rights era cases show why this is good. All too often, the police want to silence this world’s Irv Feiners because they don’t like what they have to say, and the “angry crowd” is a handy excuse.

But we pay a price for this freedom, and not everyone pays the price equally. The First Amendment imposes on us all the duty to maintain the peace even when our deepest beliefs are denounced. But that duty is doubly onerous for minorities, because they must endure such abuse more often and longer.

In a country that is 70 percent Christian, Muslims account for less than one percent of the population. Since 9/11, powerful religious and political figures have been openly campaigning to strip this tiny population of the protections of the Constitution.

In that context, the Bible Believers’ speech, though protected, was far from harmless. Their demonstrations ruined the nation’s largest public Arab American event—after the arrests in 2012, the Arab American Chamber of Commerce, sponsor of the festival for nearly 20 years, cancelled it.

The more I study the First Amendment, the more I think our system protects free speech not because it is harmless but precisely because it often does terrible harm. We may like to imagine that American society is at heart a kind of sunny Norman Rockwell small town; but it is not and never has been. Like all other societies, it embodies at its core a constant bitter struggle for cultural, religious, and political dominance. The Constitution makes a judgment that speech is the least bad way for that deadly competition to take place—not car bombs and bullets, but vicious images and words.

I wish I could talk to Irv Feiner about Bible Believers. He was a better lawyer than many who took the bar, and a better American than those who tried to ruin his life. His imagination, I think, would have room for concern about both the Muslim people of Dearborn and the aggressive bigots who destroyed their peaceful fair.

We want to hear what you think about this article. Submit a letter to the editor or write to letters@theatlantic.com.