Right, as stated in the 1st and 14th Amendments to the Constitution of the United States , to express information, ideas, and opinions free of government restrictions based on content.
A modern legal test of the legitimacy of proposed restrictions on freedom of speech was stated in the opinion by Oliver Wendell Holmes, Jr. in Schenk v. U.S. (1919): a restriction is legitimate only if the speech in question poses a "clear and present danger"
i.e., a risk or threat to safety or to other public interests that is serious and imminent. Many cases involving freedom of speech and of the press also have concerned defamation , obscenity , and prior restraint (see Pentagon Papers ). See also censorship .