Federal antitrust enforcement has undergone a radical transformation in the past decade. The change in enforcement patterns has been most noticeable in the area of merger law. The magnitude of this shift, the confusion that has characterized the case law accompanying it, and the increasing prominence of conglomerate mergers as a means to corporate expansion form the basis for this article. The primary source for regulation of mergers under the antitrust laws is section 7 of the Clayton Act, which proscribes those corporate acquisitions “where in any line of commerce in any section of the country, the effect of such acquisition may be substantially to lessen competition, or tend to create a monopoly.” Although section 7 clearly applies to all types of mergers, the construction given it by the Supreme Court in recent years has rendered it particularly ineffective for control of conglomerate mergers. In attempting to adapt section 7 to the regulation of such mergers, the government has relied upon two theoretical approaches.

This article will detail the two government approaches and analyze the limitations placed upon their application by recent decisions of the Supreme Court. At the same time, the article will also consider a third approach–rejected by the courts as outside the scope of the Clayton Act but nonetheless essential to any analysis of present and future antitrust enforcement–which emphasizes noneconomic factors, looking beyond competitive impact to the social and political implications of the concentration of corporate assets in the hands of a few dozen or hundred firms. Analysis of these three approaches will highlight the extent of the Supreme Court's shift in attitude toward merger enforcement, a shift that marks an enormous change in direction for regulation of corporate economic activity and calls for reevaluation of the Clayton Act itself. The article will conclude with consideration of the necessary elements–political and social as well as economic–of such a reevaluation and with specific suggestions for legislative reform.