What are the limits on free speech?

Although free speech is guaranteed by the First Amendment, not all speech is free from government control. Specifically, three types of speech—commercial speech, libel and slander, and obscenity—are not protected under the First Amendment and may be regulated. Commercial speech includes advertising or other speech made for business purposes, including print, radio, and television advertising. Libel is a false statement made about another made in print, while slander involves the spoken use of malicious words—both have the intent of injuring a person's character or reputation. Obscenity includes publicly offensive language or images of no social value. Whether pornography is considered "obscene" depends upon whether it is deemed to have some artistic or literary value. According to the Supreme Court's 1942 decision Chaplinsky v. New Hampshire, obscenity, lewdness, libel, and "fighting words" are not protected because "such expressions are no essential part of any exposition of ideas.''


reference: page 52, The Handy Politics Answer Book by Gina Misiroglu