Hurley v. Irish-American Gay, Lesbian and Bisexual Group of Boston
In Hurley v. Irish-American Gay, Lesbian and Bisexual Group of Boston, Inc., 515 U.S. 557 (1995), a unanimous U.S. Supreme Court held that Massachusetts may not require private citizens who organize a parade to include among the marchers a group imparting a pro-homosexual message the organizers do not wish to convey. The Court held that such a state requirement would violate the First Amendment.
Put another way, First Amendment protection against compelled-speech is not limited to situations in which an individual must personally speak the government's message. The Court also limits the government's ability to force one speaker to host or accommodate another speaker's message. See id. at 566 (state law cannot require a parade to include a group whose message the parade's organizer does not wish to send).
Justice David Souter wrote this opinion for the Court.