When a Florida preacher announced his plan to burn copies of the holy Quran at his small Gainesville church, he hoped the symbolic act of desecration would create more than just a pile of ashes. His aim was no less than to spark a conflagration between two of the world's great religions – Christianity and Islam.

The Rev. Terry Jones had important allies in his fiery gambit; free speech protections enshrined in the First Amendment, an ability to exploit the Internet, and a voracious 24-hour cable news cycle willing and able to send a hateful message around the globe in a single, shocking instant.

The strange tale of Mr. Jones and his fistful of matches cuts to the heart of the American ideal of free speech – that toler­ating expression of even the most ugly and hurtful ideas is a protection in a democratic country.

But has it gone too far?

When a US-based preacher can trigger deadly protests in Afghanistan and Kashmir, or an aborted Quran-burning in Florida prompts copycat burnings across the country, or a Seattle-based artist must go into hiding after drawing a cartoon of the prophet Muhammad, the limits of America's brand of free speech are bound to be tested – sometimes in surprising and dangerous ways.

On Oct. 6, the US Supreme Court takes up a case examining whether members of the Westboro Baptist Church of Topeka, Kan., went too far when they staged a protest at a fallen marine's funeral in Maryland. The demonstrators hoisted signs proclaiming: "You Are Going to Hell" and "Thank God for Dead Soldiers."

Fred Phelps, pastor of the Westboro church, has made a career out of using blunt and offensive statements to try to shock Americans into joining his crusade against gay rights. His followers show up at military funerals and announce that God is killing American soldiers for the sins of the country. Funeralgoers are urged to repent... or else.

In Maryland, it was too much for the grieving father, Albert Snyder, to endure. He sued. The case pits Mr. Snyder's First Amendment right to peacefully assemble in a church to mourn his son's passing against the Westboro protesters' right to chant harsh slogans and display shocking signs in their campaign for moral salvation of the nation.

"I suspect neither Phelps nor Snyder will change their point of view no matter what happens in the case," says Christina Wells, a law professor and First Amendment scholar at the University of Missouri-Columbia School of Law.

"Somebody is going to be unhappy," she says. "But the debate [surrounding the case] hopefully will foster understanding of why we have the First Amendment we do."

• • •

The essence of free speech in America is not that you can say whatever you want. There is no constitutional right to libel someone, or to produce and distribute child pornography, or to use "fighting words" that are sure to provoke fisticuffs.

In the most quoted example, there is no constitutional right to falsely yell "Fire!" in a crowded theater. Government regulation of that speech is appropriate because of the predictable outcome of the panic.

On the other hand, the First Amendment's free speech clause is intended to be broadly permissive. Mere offense is not enough to trigger government censorship.

"The problem is, once you start prohibiting speech that is offensive there is no limit to how far you can extend the concept of offensiveness," says Richard Parker, professor emeritus of communication at Northern Arizona University in Flagstaff and editor of the 2003 book "Free Speech on Trial."

This is an issue that arises on the vast majority of American college campuses through the proliferation and enforcement of speech codes designed to ban offensive speech on campus.

Free speech advocates say it is exactly the wrong lesson for young college students training to become productive citizens.

Will Creeley, a lawyer with the Foundation for Individual Rights in Education, says that the vast majority of colleges and universities in the country maintain some version of a speech code. FIRE has found only 12 schools that have no speech code. Among the no-code schools are Dartmouth College, the University of Pennsylvania, and William & Mary.

"Over 70 percent of [public and private schools monitored by FIRE] maintain restrictions on speech that would not stand if challenged in court based on relevant precedents," estimates Mr. Creeley. Rather than teaching the fundamentals of free speech and tolerance of offensive messages, he says, most schools are telling students they have a responsibility to stop hate speech, to engage in censorship.

"We have a saying here, if you go four years to a university or college and you are not once offended, you should ask for your money back," he says. "We feel there is inherent value in having your most deeply held beliefs tested."

Professor Wells, at the University of Missouri, agrees. She says universities are risk-averse and believe speech codes are a magic bullet: "Having a First Amendment is much harder than you think. We tend to view the First Amendment as a rights-giving instrument. But we really ought to see the First Amendment as providing us the space to have these really important and difficult conversations."

She adds: "When we have these controversies, it is up to us to resolve them. Not the courts, not the police, but us."

• • •

The history of the first amendment is populated by a rogues' gallery of provocateurs, crusaders, ra­cists, and assorted scoundrels. These tend to be the kinds of people who exist at the outer edges of public discourse where the boundaries of constitutional protection of offensive speech may not be entirely clear.

Consider the case of Frank Collin. In 1977, he was the leader of a Nazi group that wanted to conduct a protest march through Skokie, Ill., a Jewish community with a significant population of Holocaust survivors. The group sought a permit to parade through the village in their storm trooper uniforms displaying swastikas.

Village officials objected, and the courts agreed to block it, ruling that such a march would be a blatant provocation, a form of fighting words, unprotected by the First Amendment.

But the US Supreme Court had a different view. It reversed the lower courts and sent the case back. Ultimately, the dispute was decided by a federal appeals court in Chicago that found that free speech rights are broad enough to cover even a group of Nazis wearing swastikas marching through a community of Holocaust survivors.

"If these civil rights are to remain vital for all, they must protect not only those society deems acceptable, but also those whose ideas it quite justifiably rejects and despises," the appeals court said.

David Goldberger remembers the case well. He was legal director of the American Civil Liberties Union (ACLU) of Illinois and was one of Mr. Collin's lawyers.

The case would not have been easy for any lawyer, but it was particularly tough for a Jewish lawyer defending a Nazi pitted against Holocaust survivors. "Some folks threatened to shoot me," he says.

The ACLU lost members and financial support over the controversial case. But Mr. Goldberger, who has since retired after a career as a law professor at Ohio State's Moritz College of Law, says it was a battle well worth fighting.

"It was important that a group identified as a liberal organization with a Jewish legal director would say the First Amendment doesn't turn on the offensiveness of the speech or the noxiousness of the political philosophy that drives the speech," he says.

In 1984, Gregory Lee Johnson arrived in Dallas to participate in a street protest during the Republican National Convention. The demonstration ended at City Hall, where Mr. Johnson unfurled an American flag, doused it with kerosene, and set it on fire. Protesters simultaneously chanted: "America, the red, white, and blue, we spit on you."

No one was injured during the protest, but several onlookers said later they were deeply offended. A witness to the burning gathered up the remains of the flag and buried them, respectfully, in his backyard.

Johnson was charged with desecrating a venerated object in violation of Texas law. He was convicted and sentenced to a year in prison and ordered to pay a $2,000 fine. A state appeals court affirmed his conviction, but the Texas Court of Criminal Appeals overturned it.

The case went to the US Supreme Court. A controversy that tested the justices like no other, it left the court sharply divided. By a 5-to-4 vote, the high court ruled that Johnson could not be prosecuted for engaging in an act of symbolic speech – burning the American flag.

"If there is a bedrock principle underlying the First Amendment, it is that the government may not prohibit the expression of an idea simply because society finds the idea itself offensive or disagreeable," Justice William Brennan wrote in the majority opinion. "We have not recognized an exception to this principle even where our flag has been involved."

Justice Brennan continued: "The way to preserve the flag's special role is not to punish those who feel differently about these matters. It is to persuade them that they are wrong."

In an impassioned dissent, Justice John Paul Stevens, usually a Brennan ally on the court, said the case had nothing to do with disagreeable ideas. Johnson engaged in disagreeable conduct that diminished the value of an important national asset, Justice Stevens said.

"The ideas of liberty and equality have been an irresistible force in motivating leaders like ... the Philippine Scouts who fought at Bataan, and the soldiers who scaled the bluff at Omaha Beach," wrote Stevens, a Navy veteran of World War II.

"If those ideas are worth fighting for – and our history demonstrates that they are – it cannot be true that the flag that uniquely symbolizes their power is not itself worthy of protection from unnecessary desecration."

• • •

Another important figure in the development of free speech protections in America is Ku Klux Klan leader Clarence Brandenburg. In 1964, he was filmed delivering a speech in full white-robed regalia in the glow of a burning cross during a KKK rally in rural Ohio.

"We're not a revengent [sic] organization," Mr. Brandenburg declared, "but if our president, our Congress, our Supreme Court, continues to suppress the white, Caucasian race, it's possible that there might have to be some revengence [sic] taken."

Brandenburg was charged with breaking an Ohio law by advocating violence during his speech. He was convicted and sentenced to serve one to 10 years in prison and pay a $1,000 fine.

On appeal, the US Supreme Court reversed his conviction, announcing in a landmark decision that mere advocacy of unlawful action was fully protected by the First Amendment. What wouldn't be protected, the court said, was an intentional effort to incite imminent lawless action, like whipping a crowd into a riotous mob and sending them on a rampage.

That 1969 decision in Brandenburg v. Ohio established a high standard for the protection of free speech. But, by necessity, it leaves unresolved the critical question of precisely where the line falls between unlawful incitement and mere impassioned advocacy.

Here's where Gainesville preacher Jones reenters the picture. Was his plan to burn the stack of Qurans impassioned advocacy protected by the First Amendment or unlawful incitement to imminent lawless action?

Jones frequently mentioned that the act of burning the Quran would be a protected form of free speech. Many First Amendment scholars agree. But not all.

In the Islamic world's hair-trigger environment, certain kinds of symbolic speech may predictably spark deadly riots, lend ammunition to terrorist recruiters, and perhaps frame a mission for would-be assassins, government officials warned in the days before Jones's planned burning. With US forces on the front lines in Muslim countries, these are not insignificant threats, they said.

"Here you had a genuine concern on the part of our government that there was going to be hostile action taken toward our soldiers in the field," says former law professor Goldberger. "If you have the commander in the military theater, the head of the Defense Department, and other experts saying, 'Yes, there will be violence and it will be directed at our troops,' I leave it to you to put yourself in the place of the judge with that evidence in front of you."

He adds: "The answer is not as obvious as everyone assumed."

"I think it raises really hard questions," Wells says of the Quran-burning controversy, "if you know there could be harm and you know how upset people are and there are claims that they will [retaliate] at some point."

But she says the Quran-burning case would still fall on the side of protected speech because it would be difficult for the government to prove a direct link between a book burning in the United States and specific violent actions in the Islamic world.

There was no shortage of worldwide reaction to the plan to burn the Quran. Thousands of angry Muslims took to the streets in Afghanistan, Pak­istan, Kashmir, Iran, Indonesia, and elsewhere. At least four protesters died in Afghanistan, and 18 were killed in clashes with police in Kashmir.

In the US, Jones's announced plan inspired several others to commemorate the 9/11 terror attacks by burning, ripping, or otherwise destroying copies of the Quran.

Two preachers in Nashville, Tenn., used lighter fluid to burn the book. A New Jersey Transit employee was fired after his bosses learned that he'd destroyed part of a Quran during a 9/11 protest near ground zero in New York City. Police in Gainesville stopped a man from trying to set fire to a Quran during a demonstration.

As if not to be outdone, Pastor Phelps announced that he would burn both a copy of the Quran and the American flag on Sept. 11. He posted video of the burning book and flag on his Westboro Baptist Church website.

"God hates your false religion so we will burn your Quran to get your attention," Phelps said in a website message to Muslims. "Now the day of vengeance has come."

• • •

It was Justice Oliver Wendell Holmes who in 1919 first gave voice to the task of separating speech deserving protection from dangerous speech that did not.

"The question in every case is whether the words used are used in such circumstances and are of such a nature as to create a clear and present danger that they will bring about the substantive evils that Congress has a right to prevent," Justice Holmes wrote. "It is a question of proximity and degree."

This "clear and present danger" test was used for decades to uphold the arrest of perceived government opponents and suspected communists, who – in retrospect – never posed much of a threat to the nation. Over time, the standard evolved, beefing up free speech protections. The evolution eventually led to the 1969 Brandenburg landmark ruling protecting the advocacy of unlawful action.

Behind it all is a conviction expressed by various members of the Supreme Court through the years that what is being protected in the First Amendment's free speech clause is the free flow of ideas – the lifeblood of a democracy. It is the principle that the best way to counter a stupid idea, a hateful idea, a dangerous idea, is through the expression of better ideas.

Supreme Court Justice Louis Brandeis identified this dynamic in a 1927 case.

"To courageous, self-reliant men, with confidence in the power of free and fearless reasoning applied through the processes of popular government, no danger flowing from speech can be deemed clear and present unless the incidence of the evil apprehended is so imminent that it may befall before there is opportunity for full discussion," Justice Brandeis wrote.

"If there be time to expose through discussion the falsehood and fallacies, to avert the evil by the processes of education," he said, "the remedy to be applied is more speech, not enforced silence."

That's what happened in response to Jones's threat to burn the Quran. Muslims expressed outrage. Jones received more than a hundred death threats. But something else happened. Many others spoke out against burning the Quran, including President Obama, Gen. David Petraeus, and a number of religious leaders. Defense Secretary Robert Gates made a personal appeal to Jones in a telephone call. This outpouring of ideas fostered an international debate and an opportunity for education.

The debate culminated on the morning of Sept. 11 when Jones announced on NBC's "Today Show" that he had changed his mind about burning the Quran. "Not today, not ever," he pledged.

"That is the greatness of freedom of speech," says Goldberger, the law professor and former lawyer to a Nazi who wanted to march through Skokie. "It is the power of reason to persuade."

He adds: "What better lesson does the First Amendment teach us all than that the freest democracy is one where there is a give and take, where people listen and are capable – based on what they learn – to modify their course of conduct."

It is perhaps a forgotten footnote of history that although Frank Collin and his fellow Nazis won the right to march through Skokie, they never did.