Michigan Law Review Volume 53 Issue 1 1954 Product Competition in the Relevant Market Under the Sherman Act David Macdonald University of Michigan Law School Follow this and additional works at: https://repository.law.umich.edu/mlr Part of the Antitrust and Trade Regulation Commons, Law and Economics Commons, Legal History Commons, and the Supreme Court of the United States Commons Recommended Citation David Macdonald, Product Competition in the Relevant Market Under the Sherman Act, 53 MICH. L. REV. 69 (1954). Available at: https://repository.law.umich.edu/mlr/vol53/iss1/4 This Article is brought to you for free and open access by the Michigan Law Review at University of Michigan Law School Scholarship Repository. It has been accepted for inclusion in Michigan Law Review by an authorized editor of University of Michigan Law School Scholarship Repository. For more information, please contact
[email protected]. 1954] THE RELEVANT MAmrnT 69 PRODUCT COMPETITION IN THE RELEVANT MARKET UNDER THE SHERMAN ACT David Macdonald* NE of the most vexatious problems in antitrust law today is the 0 measurement of monopoly power in connection with section 2 of the Sherman Act.1 The federal courts have simultaneously used two methods of accomplishing this purpose.2 The first, called the "behavior" or "public injury" test, consists of analyzing the behavior of the putative monopolist and comparing it to behavior thought to be typical of monopolies. Under this approach the presence of some of these behavior patterns is considered proof that monopoly power exists. The second method, upon which more emphasis has been placed in recent years, emphasizes the measurement of the control over the "mar ket" which the monopolist exerts.3 One of the prime factors by which control is calculated is the percentage of the market occupied by the monopolist.4 The larger the percentage, the more likely that monopoly power exists.