Trusts and monopolies are concentrations of wealth in the hands of a few. Trusts and monopolies are considered harmful restraints of trade which alter normal marketplace competition, and yield undesirable price controls. To prevent trusts from creating restraints on trade or commerce and reducing competition, Congress passed the Sherman Antitrust Act in 1890. The Sherman Act is the main source of antitrust law. The Sherman Antitrust Act declared illegal "every contract, combination…or conspiracy in restraint of trade or commerce" between states or foreign countries. The Clayton Antitrust Act of 1914, amended by the Robinson-Patman Act of 1936, prohibits discrimination among customers through pricing and disallows mergers, acquisitions or takeovers of one firm by another if the effect will "substantially lessen competition." These laws are applicable to acts which affect interstate commerce, which has a very broad interpretation.
The Antitrust Division of the U.S. Department of Justice is responsible for enforcing antitrust laws for the federal government, but private lawsuits may also be brought to curb antitrust activities. Most if not all states have comparable statutes prohibiting monopolistic conduct, price fixing agreements, and other acts in restraint of trade having strictly local impact.
