Williamson Oil Co. v. Philip Morris USA

Beginning in 1993, Philip Morris (defendant) sharply cut cigarette prices in a highly concentrated market where five firms held 97 percent of sales, and rival manufacturers matched the cuts; later, as Philip Morris raised prices, the others again matched, settling on roughly identical increases repeatedly through 2000. Williamson Oil and other wholesalers (plaintiffs) sued Philip Morris and other manufacturers, alleging the parallel increases were a price-fixing conspiracy. The district court granted the manufacturers summary judgment, and the wholesalers appealed.

Whether a price-fixing plaintiff relying on parallel pricing must present plus-factor evidence tending to exclude the possibility that the defendants acted independently.