Freedom of speech in the United States is protected by the First Amendment to the United States Constitution and by many state constitutions and state and federal laws, with the exception of obscenity, defamation, incitement to riot, and fighting words,^[1] as well as harassment, privileged communications, trade secrets, classified material, copyright, patents, military conduct, commercial speech such as advertising, and time, place and manner restrictions.

Criticism of the government and advocacy of unpopular ideas that people may find distasteful or against public policy, such as racism, sexism, and other hate speech are almost always permitted. There are exceptions to these general protections, including the Miller test for obscenity, child pornography laws, speech that incites imminent lawless action, and regulation of commercial speech such as advertising. Within these limited areas, other limitations on free speech balance rights to free speech and other rights, such as rights for authors and inventors over their works and discoveries (copyright and patent), protection from imminent or potential violence against particular persons (restrictions on fighting words), or the use of untruths to harm others (slander). Distinctions are often made between speech and other acts which may have symbolic significance.

Flag desecration has continually, albeit controversially, been protected by the First Amendment, despite state laws to the contrary. A Constitutional Amendment has been introduced to contravene the First Amendment’s protection on flag burning, but it has failed to acquire the requisite enactment by all the states.

Despite the exceptions, the legal protections of the First Amendment are some of the broadest of any industrialized nation, and remain a critical, and occasionally controversial, component of American jurisprudence.