In 1911, the Supreme Court ordered the breakup of Standard Oil — at the time controlling roughly 90 percent of U.S. oil refining — into 34 separate companies. The case established that a firm achieving dominance through exclusionary practices that harm competition, rather than through superior products and efficiency, violated the Sherman Antitrust Act. Over a century later, the same statutory framework governs whether Amazon can acquire iRobot, whether Google can pay Apple for default search placement, and whether hospital systems can merge. The tools are old; the markets are new.
What it is
Antitrust law is the body of statute and case law that prohibits conduct and transactions that substantially reduce competition. In the United States, three statutes form the core framework:
Sherman Antitrust Act (1890): Section 1 prohibits contracts, combinations, and conspiracies in restraint of trade (price-fixing, market allocation). Section 2 prohibits monopolization — using exclusionary conduct to acquire or maintain monopoly power, as distinct from achieving dominance through competition on the merits.
Clayton Act (1914): prohibits mergers and acquisitions that may substantially lessen competition, and specific anticompetitive practices including exclusive dealing and tying arrangements.
FTC Act (1914): creates the Federal Trade Commission and prohibits unfair methods of competition and deceptive practices.
The DOJ Antitrust Division and the FTC share enforcement responsibility, reviewing proposed mergers, investigating exclusionary conduct, and bringing litigation against Sherman Act violations.
The intended effect
Antitrust's stated purpose is to protect competition — not competitors. A firm that drives rivals out of business by producing better products at lower prices is competing on the merits; a firm that drives rivals out by predatory pricing, exclusive dealing that forecloses competitive channels, or agreements to divide markets is engaging in exclusionary conduct that antitrust is designed to prevent.
The consumer welfare standard, articulated in the 1970s and dominant through the 2010s, evaluates antitrust conduct by its effect on prices, output, and consumer choice. Recent enforcement has broadened to include effects on workers, suppliers, and innovation — reflecting debate about whether consumer welfare alone fully captures competitive harm.
The tradeoff
Antitrust enforcement involves real tradeoffs. Aggressive intervention can prevent efficiency-enhancing mergers alongside harmful ones. Conservative enforcement allows market power to accumulate in platform industries with large network effects. The Congressional Budget Office's analysis of merger activity documents how merger waves have increased concentration in many sectors, prompting renewed enforcement debate.
How it plays out in practice
The 2022–2024 period saw major antitrust actions against Google (search advertising and app store monopolization), Amazon (third-party seller practices), and Meta (Instagram and WhatsApp acquisitions). The DOJ's Google antitrust verdict in 2024 — finding that Google illegally maintained its search monopoly through exclusive default agreements — represents the most significant antitrust ruling in technology markets since the Microsoft case, and will determine how antitrust applies to platform search for the coming decade.
