Sherman Antitrust Act of 1890

Per se illegality—Business practices that are deemed illegal regardless of their economic rationale or their consequences
- Under the Sherman Act, price-fixing schemes are viewed as illegal per se
Rule of reason—Used by a court to examine the reasons for certain business practices and their effects on competition before ruling on legality
- Under the Sherman Act, not all monopolies are illegal; only those which obtained monopoly power using abusive strategies, such as predatory pricing