Sherman Anti-Trust Act

Section one of the Sherman Act provides that "[e]very contract, combination in the form of trust or otherwise, or conspiracy, in restraint of trade or commerce among the several states, or with foreign nations is hereby declared to be illegal." The broad language of this section has been slowly defined and narrowed through judicial decisions.

The courts have interpreted the act to forbid only unreasonable restraints of trade. The Supreme Court promulgated this flexible rule, called the Rule of Reason, in Standard Oil Co. of New Jersey v. United States, 221 U.S. 1, 31 S. Ct. 502, 55 L. Ed. 619 (1911). Under the Rule of Reason, the courts will look to a number of factors in deciding whether the particular restraint of trade unreasonably restricts competition. Specifically, the court considers the makeup of the relevant industry, the defendants' positions within that industry, the ability of the defendants' competitors to respond to the challenged practice, and the defendants' purpose in adopting the restraint. This analysis forces courts to consider the pro-competitive effects of the restraint as well as its anticompetitive effects.

The Supreme Court has also declared certain categories of restraints to be illegal per se: that is, they are conclusively presumed to be unreasonable and therefore illegal. For those types of restraints, the court does not have to go any further in its analysis than to recognize the type of restraint, and the plaintiff does not have to show anything other than that the restraint occurred.

Restraints of trade can be classified as horizontal or vertical. A horizontal agreement is one involving direct competitors at the same level in a particular industry, and a vertical agreement involves participants who are not direct competitors because they are at different levels. Thus, a horizontal agreement can be among manufacturers or retailers or wholesalers, but it does not involve participants from across the different groups. A vertical agreement involves participants from one or more of the groups—for example, a manufacturer, a wholesaler, and a retailer. These distinctions become difficult to make in certain fact situations, but they can be significant in determining whether to apply a per se rule of illegality or the Rule of Reason. For example, horizontal market allocations are per se illegal, but vertical market allocations are subject to the rule-of-reason test.