In the case of Brandenburg v. Ohio, 1968, the U.S Supreme Court held that government cannot punish inflammatory speech unless it is directed to inciting or producing imminent lawless action and is likely to incite or produce such action. The case involved a Ku Klux Klan leader named Clarence Brandenburg who was convicted under an Ohio criminal syndicalism law for speeches promoting violence towards racial and political groups at a KKK rally. The court's decision overturned his conviction, ruling that the Ohio law violated his right to free speech as protected by the First Amendment of the Constitution. This landmark decision established what has come to be known as "the imminent lawless action test", which remains one of key standards for defining constitutional limits on freedom of expression.

In the dissenting opinion of Brandenburg v. Ohio, there was a concern about the potential for this ruling to protect inflammatory speech that could incite violence or illegal activity. The justices argued that while they agreed with protecting freedom of speech, they believed there should be limitations when it comes to promoting harm or lawlessness. They worried that by setting such a high bar for what constitutes incitement (imminent lawless action), many harmful speeches would go unpunished and potentially lead to real-world violence and chaos. Furthermore, these justices expressed concerns over how difficult it might be in practice to determine whether someone intended their words to incite immediate lawlessness versus simply expressing general support for unlawful actions.