The First Amendment of the United States Constitution protects the right to freedom of religion and freedom of expression from government interference. Although adopted as part of the Bill of Rights in 1791, most First Amendment doctrine is a result of twenty-century litigation. The Supreme Court interprets the extent of the protection afforded to these rights. The First Amendment has been interpreted by the Court as applying to the entire federal government even though it is only expressly applicable to Congress. It wasn't until 1925, in Gitlow v. New York, that the Supreme Court extended the First Amendment freedoms of speech and the press to the states through the Fourteenth Amendment due process clause.
The government may regulate obscenity. Speech defined as obscenity is not protected by the First Amendment Obscenity is speech that
Nor is speech likely to incite violence, lawless action, or danger to the nation's security protected. Commercial speech is protected under an intermediate level of scrutiny and the government can ban deceptive or illegal commercial speech.
The right to free speech includes other methods of expression that communicates a message. As new methods of communication are developed, they have presented unique challenges to First Amendment doctrine.