What federal law prohibits price-fixing among competitors?

The federal law that prohibits price-fixing among competitors is the Sherman Antitrust Act.

Section 1 of the Sherman Act prohibits contracts, combinations, or conspiracies that unreasonably restrain interstate or foreign commerce. An agreement among competing businesses to raise, lower, maintain, or otherwise coordinate prices is a classic horizontal restraint and is generally treated as unlawful per se. The offense is the agreement among competitors, not merely the fact that their prices happen to be identical.

Congress enacted the Sherman Act in 1890 during growing concern about powerful trusts and concentrated economic control. The law also addresses monopolization under Section 2, making it a foundation of U.S. antitrust enforcement. The Justice Department identifies price-fixing, bid-rigging, and market-allocation agreements as major Sherman Act violations.

The Federal Trade Commission Act separately prohibits unfair methods of competition, the Clayton Act addresses practices such as certain anticompetitive mergers, and the Robinson–Patman Act focuses chiefly on certain forms of discriminatory pricing. Those statutes may overlap with antitrust enforcement, but the standard quiz answer for competitor price-fixing is the Sherman Act.