"Gitlow v. New York, case in which the U.S. Supreme Court ruled on June 8, 1925, that the U.S. Constitution’s First Amendment protection of free speech, which states that the federal “Congress shall make no law…abridging the freedom of speech,” applied also to state governments. The decision was the first in which the Supreme Court held that the Fourteenth Amendment’s due process clause required state and federal governments to be held to the same standards in regulating speech."
Quoted from britannica, hope this answers your question!