The definitive antitrust statute, passed by Congress in 1890, that prohibits monopolies or unreasonable combinations of companies to restrict or in any way control interstate commerce. Specifically outlawed is two or more persons engaging in monopolistic practices, such as price fixing, although it does not outlaw price-fixing per se. It was amended in 1914 by the Clayton Act, which outlaws interlocking directorates and deals with acquisitions that aim to restrain or eliminate competition.