Freedom of speech in the United States

Freedom of speech in the United States is the constitutional protection against government abridgment of expression, chiefly under the First Amendment, subject to recognized legal limits.

First Amendment to the United States Constitution: The constitutional amendment that protects speech, press, religion, assembly, and petition from government abridgment. Its Speech Clause is the central textual source of protection.
Schenck v. United States: A 1919 Supreme Court case upholding convictions for anti-draft leaflets during World War I. Its clear-and-present-danger test once framed when advocacy could be punished.
Prior restraint: Government action that prevents expression before it is communicated or published. Courts treat advance censorship as especially difficult to justify.
Defamation: A false statement of fact that harms another's reputation and may give rise to civil liability. Constitutional rules limit liability for defamatory statements about public officials and figures.
Chilling effect: The deterrence of lawful expression caused by fear of punishment, liability, or other consequences. Courts consider whether uncertain or severe penalties may silence protected speech.
Incorporation of the Bill of Rights: The process by which the Fourteenth Amendment makes most Bill of Rights protections applicable to state and local governments. It extended First Amendment speech protections beyond the federal government.
Brandenburg v. Ohio: A 1969 Supreme Court decision protecting advocacy unless it is directed to and likely to produce imminent lawless action. Its imminence rule sharply limits punishment of political advocacy.
Symbolic speech: Conduct intended to convey a message that may receive constitutional protection as expression. Flag burning and protest gestures show that speech extends beyond words.
Incitement: Advocacy intended and likely to produce imminent lawless action, which government may punish under Brandenburg. It is a narrow route for punishing advocacy without outlawing abstract ideas.
Campaign finance in the United States: The system of laws governing money raised and spent in American elections. Campaign spending cases test how far speech protections constrain election regulation.

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