In 1908 the U.S. Supreme Court decided Loewe v. Lawlor . In 1902 the Hatters' Union instituted a nationwide boycott of the hats made by a nonunion company in Connecticut. Owner Dietrich Loewe brought suit against the union for unlawful combinations to restrain trade in violation of the Sherman Antitrust Act. The Court ruled that the union was subject to an injunction and liable for the payment of triple damages. In 1915 Justice Oliver Wendell Holmes, speaking for the Court, again decided in favor of Loewe, upholding a lower federal court ruling ordering the union to pay damages of $252,130. . This was not a typical case in which a few union leaders were punished with short terms in jail; specifically, the life savings of several hundreds of the members were attached. The lower court ruling established a major precedent, and became a serious issue for the unions. The Clayton Act of 1914 presumably exempted unions from the antitrust prohibition and established for the first time the Congressional principle that "the labor of a human being is not a commodity or article of commerce". However, judicial interpretation so weakened it that prosecutions of labor under the antitrust acts continued until the enactment of the Norris-La Guardia Act in 1932.
Question: What did Sherman Antitrust Act prohibit?
Answer: restrain trade