According to the key provisions of the Sherman Antitrust Act, trusts and monopolies were "illegal."
The Sherman Anti-Trust Act was the first Federal act that banned monopolistic business practices. The Sherman Antitrust Act of 1890 was the first measure passed by the U.S. Congress to prohibit trusts.
It received its name for Senator John Sherman of Ohio, who served as a chairman of the Senate finance committee and the Secretary of the Treasury under President Hayes.