Clayton Antitrust Act of 1914

That regime started with the Sherman Antitrust Act of 1890, the first Federal law outlawing practices that were harmful to consumers (monopolies, cartels, and trusts).

Since the Sherman Antitrust Act of 1890, courts in the United States had interpreted the law on cartels as applying against trade unions.

During its proceedings, and in anticipation of its first report on October 23, 1914, legislation was introduced by Alabama Democrat Henry De Lamar Clayton Jr. in the U.S. House of Representatives.

Substantively, the act seeks to capture anticompetitive practices in their incipiency by prohibiting particular types of conduct not deemed in the best interest of a competitive market.

Exclusive dealing, tying, and mergers are all agreements, and theoretically, within the reach of Section 1 of the Sherman Act.

The government often employs the Herfindahl-Hirschman Index (HHI) test for market concentration to determine whether the merger is presumptively anticompetitive; if the HHI level for a particular merger exceeds a certain level, the government will investigate further to determine its probable competitive impact.

§ 18a, requires that companies notify the Federal Trade Commission and the Assistant Attorney General of the United States Department of Justice Antitrust Division of any contemplated mergers and acquisitions that meet or exceed certain thresholds.

Section 8 of the Act refers to the prohibition of one person of serving as director of two or more corporations if the certain threshold values are met, which are required to be set by regulation of the Federal Trade Commission, revised annually based on the change in gross national product, pursuant to the Hart–Scott–Rodino Antitrust Improvements Act.

Because the act singles out exclusive dealing and tying arrangements, one may assume they would be subject to heightened scrutiny, perhaps they would even be illegal per se.

Under the 'rule of reason', the conduct is only illegal, and the plaintiff can only prevail, upon proving to the court that the defendants are doing substantial economic harm.