Life & Health Ins. Co., 737 F.2d 1433,1437 (5th Cir. 1984) (“the Supreme Court’s analysis [in Interstate Circuit] was predicated upon the rule of reason”).  359 U.S. 207 (1959).  Id.
A horizontal price-fixing conspiracy remains precisely that, regardless of whether it was created by an express agreement or an unwritten agreement through a series of vertical agreements. The Court dusted off and cited Klor’s, Inc. v. Broadway-Hale Stores, Inc., 359 U.S. 207 (1959), for this proposition – that a retailer is per se liable for facilitating a distributors’ horizontal group boycott because group boycotts are per se illegal, not because the vertical arrangements between the retailer and distributors created and organized the horizontal cartel. This reasoning was critical for the court: “the question is whether the vertical organizer of a horizontal conspiracy designed to raise prices has agreed to a restraint that is any less anticompetitive than its co-conspirators, and can therefore escape per se liability.