The Reno v. American Civil Liberties Union from 1997 violated the freedom of speech as guaranteed by the First Amendment.
In this landmark 1997 case, all nine justices of the Supreme Court voted down the provisions of CDA and the First Amendment's protection was expanded to include the internet and the internet now is a the same level as the written and spoken media. This is really important ruling and the first one that dealt with what was posted on the internet.