SOMETIMES SPEECH TAKES place at an appropriate time, in an appropriate place, and in an appropriate manner, yet it still infringes on the rights of others. In these cases, it is the content of the speech, rather than the conduct of the speaker, that is the problem. For example, a person giving a speech might urge the audience to commit a crime—to attack police officers, burn a building, or even lynch a person.

The act of urging a person to break the law, any law, is known as incitement. All incitement cases involve speech: Communication is the only way for one person to convince another person to commit a crime. The question the Supreme Court had to decide was whether such speech was protected by the First Amendment.

The first incitement case heard by the Supreme Court involved the case of Charles T. Schenck...