What case established the "clear and present danger" test for free speech?

The case that established the "clear and present danger" test for free speech is Schenck v. United States. In this 1919 Supreme Court ruling, Justice Oliver Wendell Holmes, Jr. introduced the concept that speech could be limited if it presents a clear and present danger of causing significant harm, particularly in situations where national security is at stake, such as during wartime.

Schenck involved Charles Schenck, who had distributed leaflets urging resistance to the military draft during World War I. The Court held that his actions were not protected by the First Amendment because they posed a imminent risk of obstructing the draft, thus justifying restrictions on free speech under certain circumstances where the potential for harm is evident. This foundational ruling clarified that the right to free expression is not absolute, particularly when it comes to speech that could incite unlawful action or endanger public safety.

In contrast, the other cases listed focus on different aspects of free speech and do not establish the clear and present danger test. For instance, Brandenburg v. Ohio refined the standards for limiting speech but did so much later and emphasized incitement to imminent lawless action. New York Times v. Sullivan addressed issues of libel and the need for proving