D is an unincorporated association that now includes 32 separately owned professional football teams. Each team has its own name, colors, and logo, and owns related intellectual property. Like each of the other teams in the league, each have their own distinctive names, colors, and marks that are well known to millions of sports fans. Prior to 1963, the teams made their own arrangements for licensing their intellectual property and marketing trademarked items such as caps and jerseys. In 1963, the teams formed National Football League Properties (NFLP) to develop, license, and market their intellectual property. Between 1963 and 2000, NFLP granted non-exclusive licenses to a number of vendors, permitting them to manufacture and sell apparel bearing team insignias. P was a licensee. In December 2000, the teams voted to authorize NFLP to grant exclusive licenses, and NFLP granted Reebok International Ltd. an exclusive 10-year license. P's non-exclusive license was not renewed. P sued alleging that the agreements between the NFL, its teams, NFLP, and Reebok violated §§ 1 and 2 of the Sherman Act. Ds averred that the teams, NFL, and NFLP were incapable of conspiring within the meaning of § 1 “because they are a single economic enterprise, at least with respect to the conduct challenged.” The district court granted Ds’ motion for summary judgment. The court concluded, “that in that facet of their operations they have so integrated their operations that they should be deemed a single entity rather than joint ventures cooperating for a common purpose.” P appealed. The Seventh Circuit agreed with P that “when making a single-entity determination, courts must examine whether the conduct in question deprives the marketplace of the independent sources of economic control that competition assumes.” It discounted the significance of potential competition among the teams regarding the use of their intellectual property because the teams “can function only as one source of economic power when collectively producing NFL football.” P appealed. The Supreme Court granted certiorari.