United States v. Grinnell Corp.
Writing for the Court, Justice William Douglas explained:
|“||The offense of monopoly under § 2 of the Sherman Act has two elements: (1) the possession of monopoly power in the relevant market and (2) the willful acquisition or maintenance of that power as distinguished from growth or development as a consequence of a superior product, business acumen, or historic accident. We shall see that this second ingredient presents no major problem here, as what was done in building the empire was done plainly and explicitly for a single purpose. In United States v. du Pont & Co., 351 U.S. 377, 391, we defined monopoly power as "the power to control prices or exclude competition." The existence of such power ordinarily may be inferred from the predominant share of the market. In American Tobacco Co. v. United States, 328 U.S. 781, 797, we said that "over two-thirds of the entire domestic field of cigarettes, and ... over 80% of the field of comparable cigarettes" constituted "a substantial monopoly." In United States v. Aluminum Co. of America, 148 F.2d 416, 429, 90% of the market constituted monopoly power. In the present case, 87% of the accredited central station service business leaves no doubt that the congeries of these defendants have monopoly power -- power which, as our discussion of the record indicates, they did not hesitate to wield -- if that business is the relevant market.||”|
United States v. Grinnell Corp., 384 U.S. 563, 570-71, 86 S. Ct. 1698, 1704 (1966).