In the American Steel Foundries v. Tri-City Central Trades Council case of 1921, the U.S Supreme Court ruled in favor of American Steel Foundries. The company had sued Tri-City Central Trades Council and other labor unions for organizing a boycott against its products due to a labor dispute at one of its foundries. The court held that such secondary boycotts were unlawful as they constituted an illegal restraint on trade under the Sherman Antitrust Act, which was designed to prevent monopolies and promote competition in business practices. This ruling significantly impacted future relations between businesses and labor unions by limiting union tactics during disputes with employers.

In the dissenting opinion for American Steel Foundries v. Tri-City Central Trades Council, Justice Oliver Wendell Holmes Jr. argued that the majority's decision to grant an injunction against a labor union was based on an overly broad interpretation of what constitutes illegal activity by such organizations. He contended that unions should be allowed to exert economic pressure on employers through strikes and boycotts as long as they do not resort to violence or other unlawful means. Furthermore, he disagreed with the majority's view that picketing is inherently coercive and therefore illegal, asserting instead that it is a legitimate form of peaceful protest protected under the First Amendment right to free speech. In his view, only when picketing involves intimidation or threats should it be considered illegal.