In Police Department of Chicago v. Mosley (1972) 408 U.S. 92, a 1972 case, the United States Supreme Court considered a Chicago ordinance that generally prohibited picketing within 150 feet of a school, but made a specific exception for picketing in a labor dispute. The plaintiff was a man who frequently picketed, always peacefully, outside a high school, carrying a sign that stated that the high school discriminated racially. He sued for injunctive and declaratory relief because he was told that, if he picketed after the effective date of the ordinance, he would be arrested. (Mosley, supra, 408 U.S. at pp. 92-93.) The court held that the ordinance violated the First Amendment and the equal protection clause of the Fourteenth Amendment because of the ordinance's "impermissible distinction between labor picketing and other peaceful picketing." (Mosley, supra, at p. 94.) "The central problem with Chicago's ordinance is that it describes permissible picketing in terms of its subject matter. Peaceful picketing on the subject of a school's labor-management dispute is permitted, but all other peaceful picketing is prohibited. The operative distinction is the message on a picket sign. But, above all else, the First Amendment means that government has no power to restrict expression because of its message, its ideas, its subject matter, or its content. " (Mosley, supra, at p. 95.) The Mosley court concluded: "Necessarily, then, under the Equal Protection Clause, not to mention the First Amendment itself, government may not grant the use of a forum to people whose views it finds acceptable, but deny use to those wishing to express less favored or more controversial views. And it may not select which issues are worth discussing or debating in public facilities. There is an 'equality of status in the field of ideas,' and government must afford all points of view an equal opportunity to be heard. Once a forum is opened up to assembly or speaking by some groups, government may not prohibit others from assembling or speaking on the basis of what they intend to say. Selective exclusions from a public forum may not be based on content alone, and may not be justified by reference to content alone." (Mosley, supra, 408 U.S. at p. 96.)