Antitrust law exists in order to keep markets competitive. By way of antitrust law, businesses and ultimately consumers can find the best possible goods and services available to them at the lowest competitive prices. The purpose behind federal and state antitrust law is to prevent anti-competitive behavior by corporations that can take form in a number of fairly nuanced ways. Generally, such anticompetitive actions harm purchasers of products or services by keeping stable or increasing the price of the products or services. Lawsuits can be brought on behalf of individual purchasers or on behalf of groups of purchasers.

Federal Law

The most well-known federal antitrust law is the Sherman Act. Section 1 of the Sherman Act prohibits companies and individuals from conspiring or acting in concert to prevent or reduce competition in the market for a particular product or service. Persons who directly pay the prices set by the conspirators have been damaged and can bring suit to put a stop to the illegal conspiracy.

Examples of some illegal actions under Section 1 of the Sherman Act include: (a) horizontal price fixing - e.g., several companies get together and agree to charge customers certain prices for a particular product or products; (b) vertical price fixing - e.g., when a manufacturer and a distributor agree to fix the resale price that the distributor will charge for a particular product or products; and (c) allocation of territories or customers - e.g., when several companies agree that they will not compete with each other with respect to particular geographic territories or particular customers.

Section 2 of the Sherman Act prohibits companies and individuals from abusing their abusing their monopoly power in the market for a particular product or service. An example of a violation of Section 2 of the Sherman Act is a company with monopoly power in the market for a particular product taking deliberate steps to drive its competitors out of business, thereby allowing it to set prices at unreasonably high levels. Carey & Danis, LLC is lead counsel in the Microsoft Antitrust Litigation, where Microsoft is alleged to have violated Section 2 of the Sherman act in just such a manner.

State Law

State antitrust laws sometimes protect consumers in a more direct fashion than federal laws. Although state antitrust laws have the same substantive underpinnings as federal antitrust laws, a direct purchaser can have standing to bring a claim in many states. In other words, while many state antitrust laws follow the federal antitrust laws, certain states allow consumers (who may not have purchased directly from the conspirators) to bring suits to address violations of that state's antitrust law. Like federal law, state antitrust laws also make price fixing conspiracies and abuse of monopoly power illegal. Currently, consumer actions can be brought under the antitrust laws of approximately 19 "indirect purchaser" states and the District of Columbia.