Many colleges have rules against “hate speech.” But racial supremists and others fire back that the counter-demonstrators who yell back “fascist” and other epithets are engaging in hate speech too. In the wake of the violence at the University of Virginia at Charlottesville, higher education institutions across the country are facing a dilemma in how to handle controversial speakers, attempting to balance the need for open dialogue with the risk of physical violence on campus.

Unfortunately, we do not teach much about “free speech” and the restrictions to speech. As a result, many graduate into society believing that they can say anything they want.

Yes, the First Amendment reads: “Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof; or abridging the freedom of speech, or of the press; or the right of the people peaceably to assemble, and to petition the Government for a redress of grievances.”

Some may recall that free speech does not extend to yelling “Fire!” in a crowded theater. But speech can cause harm in many other ways. And that provides the basis for a considerable number of legal restrictions on speech.

It is our U.S. Supreme Court that encounters the many ways speech harms others, and has imposed limitations on freedom of speech. In many cases, these limitations are specific to various institutions including the press, the courtroom, the government, industry, schools, and other venues. And restrictions may be crafted differently in different states.

Libel and slander laws limit what we can write and say about others, although if the target is a public figure, only a statement made with malice is actionable.

In Kansas, you cannot parade obscene material in public; but medical doctors and teachers have an exemption from obscenity restrictions for appropriate materials in the doctor’s office or classroom. There is no free speech right when it comes to child pornography.

Sedition is speech or organization to overthrow the government. Speech that promotes armed insurrection is illegal. Incitement to riot is therefore a no-no. Get in someone’s face and shout fighting words and get slugged in response; you can probably forget claiming assault.

Lie in court and you can be charged with perjury—no freedom to say anything you want there. Legal settlements can also involve a non-disclosure agreement; you agree to curb your freedom of speech.

In some civilian jobs, as well as military service and government, there is classified information that may not be revealed to the public. Schools cannot disclose grades and hospitals are restricted in issuing patient information. –No public disclosure of your social security number. And of course there are those government leaks, acts also subject to prosecution.

So there are many situations where “freedom of speech” in America is rightly constrained. And nearly all center on the issue of preventing harm. There are additional restrictions that can be applied in academic institutions, based on varying state laws, whether the school is public or private, and even the nature of the environment (a crowded downtown urban campus versus a spacious rural setting).

Looking back on the violence at the University of Virginia at Charlottesville, various authorities have noted that the torches could have been banned or confiscated, as well as the guns and clubs. And there was no right to be masked; such individuals can be excluded.

These tragic events should provide American teachers with a teachable moment to discuss the complexities of “freedom of speech” and its limitations. Yet, the reaction of many administrators is to avoid controversial speakers and barricade the doors. Meanwhile, the ignorance of the younger generations continues. While some recognized the Nazi swastika, I have yet to locate a student who knows what the symbol was on other shields: crossed bundles of sticks forming the handle to a battleaxe. Those were “fasces,” Mussolini’s symbol for fascism. You can be pretty sure that our 90-year-old World War II veterans know. That is why “freedom of speech” is culturally-dependent.

There is no better time than now for social studies teachers from high school up to seize this teaching moment to discuss our very complicated freedom of speech. And the best textbook for that is Stanley Fish’s book, clearly titled: “There’s No Such Thing as Free Speech…and It’s a Good Thing Too.”