The French, of course, are no more bound to accept the findings of the bishop of Rome than they are to be guided by the Supreme Court’s rulings on our Constitution’s free speech guarantee. But given the possible ripple effects of Charlie Hebdo’s mistreatment of Islam’s most sacred religious figure, at least people in this country should understand the limits America’s highest court has placed on free speech.

In 1919, the Supreme Court ruled speech that presents a “clear and present danger” is not protected by the First Amendment. Crying “fire” in a quiet, uninhabited place is one thing, the court said. But “the most stringent protection of free speech would not protect a man in falsely shouting fire in a theater and causing a panic.”

Twenty-two years later, the Supreme Court ruled that forms of expression that “inflict injury or tend to incite an immediate breach of the peace” are fighting words that are not protected by the First Amendment.

If Charlie Hebdo’s irreverent portrayal of Mohammed before the Jan. 7 attack wasn’t thought to constitute fighting words, or a clear and present danger, there should be no doubt now that the newspaper’s continued mocking of the Islamic prophet incites violence. And it pushes Charlie Hebdo’s free speech claim beyond the limits of the endurable.