Final answer:
The landmark case of Schenck v. United States established that the 'Clear and Present Danger' doctrine could limit the freedom of speech. Screaming 'fire' in a crowded theater is not protected by the First Amendment if it poses a clear and present danger to public safety.
Step-by-step explanation:
In the landmark case of Schenck v. United States, the Supreme Court ruled that the government could limit the freedom of speech when it posed a 'clear and present danger' to the nation. This case involved Charles Schenck, who was distributing pamphlets urging men to resist the draft during World War I. The Court held that his actions were not protected by the First Amendment because they created a clear and present danger to the recruitment efforts of the military.
Screaming 'fire' in a crowded theater is often used as an example to illustrate the limits of free speech. If such an act poses a clear and present danger to public safety, it would not be protected by the First Amendment. For example, if someone were to falsely shout 'fire' in a theater, causing a panic that leads to injuries, they could be held accountable for their actions.
Learn more about Limitations on freedom of speech