Opinion summary
Etalia.ai summary of the majority opinion
The case involved the Grinnell Corporation, which was accused of monopolizing the fire alarm and burglar alarm services market in violation of Section 2 of the Sherman Act. The Supreme Court held that Grinnell had indeed engaged in anticompetitive practices by acquiring competitors and controlling a dominant share of the market through its subsidiaries. The Court found that this behavior constituted an unlawful monopoly because it restricted competition and maintained control over prices within these markets. It emphasized that possessing a large market share is not inherently illegal unless accompanied by exclusionary or predatory conduct aimed at suppressing competition. Ultimately, the decision reinforced legal standards for determining when business practices cross into illegal monopolization under antitrust laws.
Opinion written by Justice Douglas
Decided 13 Jun 1966 · Official report