Answer:
The First Amendment of the United States Constitution states that "Congress shall make no law [...] abridging the freedom of speech, or of the press [...]."
However, one should not misunderstood this amendment: there are certain categories of speech that are not protected by the First Amendment and the speaker's freedom will depend on where he is, what he says and how he says it. These categories include fraud, threats, obsenity, speeches that incite lawless action or illegal conduct or that violate intellectual property law, among others.
