Sherman Antitrust Act. Sherman Antitrust Act, 1890, first measure passed by the U.S. Congress to prohibit trusts; it was named for Senator John Sherman. Prior to its enactment, various states had passed similar laws, but they were limited to intrastate businesses.s a result of President Theodore Roosevelt's trust-busting campaigns, the Sherman Act began to be invoked with some success, and in 1904 the Supreme Court upheld the government in its suit for dissolution of the Northern Securities Company.