“Free speech is an absolute!” is the conclusion of many discussions of the murderous attack on the French satire publisher Charlie Hebdo and North Korean hack attack of SONY’s movie. This level of discussion is embarrassingly shallow.

Language that is only “offensive” is indeed protected. The U.S. Supreme Court decision in Hustler Magazine vs. Falwell stated “…that it is precisely because language gives offense that it needs to be protected. Indeed, if it is the speaker’s opinion that gives offense, that consequence is a reason for according it constitutional protection.” But there is other speech that is not protected.

Should we allow plans for an atomic bomb to be spread widely in newspapers or across the Internet? Of course not. When the chain reaction concept was born in the early 1900s, that research moved behind closed doors. College dissertations were defended in secret. Results were highly classified. Research on bacterial warfare was also “censored” from the public and much of it remains confidential today.

Just last year, a new technique for growing the deadly flu virus of 1918 in ferrets was embargoed by the scientific community. Young and naive scientists protested that the U.S. had never censored research before; they were ignorant of their own history. Just as we cannot yell “Fire!” in a crowded theater, we have good reason to prevent this “free speech” that could kill millions.

We also prosecute those who would advocate overthrow of the government or threaten the life of the President. A genuine threat to harm any person constitutes the crime of making a terrorist threat.

And what about human “dignity.” Consider the tragedy where teenagers were killed and mangled in a West Coast car crash. Those first on the scene took photographs and posted the gruesome images online, much to the distress of parents and family members. That is “free speech” in the U.S. but newspaper editors chose not to publish it—it would not be illegal but it is wrong.

But we do prosecute indecency. Obscenity is limited by a U.S. Supreme Court ruling. Kansas law allows physicians and teachers to use photos on sex education in the context of the hospital or classroom that we cannot display on the street corner. That limitation on speech is defined by community standards. In 1964, U.S. Supreme Court Justice Potter Stewart described his test for obscenity in Jacobellis v. Ohio: “I shall not today attempt further to define the kinds of material I understand to be embraced within [‘hard-core pornography’]…. But I know it when I see it.” So communities establish their standards. But in the Internet community, the U.S. has no standard and little children view material they should not see.

Within these last months in the U.S., we have seen Islamic State (ISIS) rebels recruit online. Hundreds of teenagers have left their homes to join the war in Iraq and Syria. The wimpy U.S. response was to produce counter online advertisements. Blocking those recruitment websites was not considered legitimate because it was “free speech.” But other countries are willing to take action.

Article 19 of the U.N. Universal Declaration of Human Rights recognized in the International Covenant on Civil and Political Rights asserts that “…everyone shall have the right to freedom of expression…” in speech, print, art or other media. However, Article 19 also explains that exercise of these rights may be “…subject to certain restrictions.” Those limitations include respecting “…the rights or reputation of others” and “…the protection of national security or of public order, or of public health or morals.”

Foreign countries recognize the gray areas of free-speech. For instance, some European countries restrict libel of living persons on the Internet. And China has no qualms using their great firewall to block those Internet ISIS calls to come-and-kill. Why do we consider it a crime to threaten to kill another person in the U.S., but not a crime to recruit youngsters to kill people elsewhere?

Universities implement “hate speech” rules and cancel campus speakers—probably when they should not. “Free speech” is not a black-and-white issue. We do have laws that clearly restrict some speech. But there is a continuum of gray situations and different cultures will draw the line at different mid-points.

Some would argue that Internet censorship is a “slippery slope.” But some speech is not on a slippery slope, but at the bottom of a gutter.