Eastman Kodak Company (Kodak) (defendant) manufactures and sells photocopiers and micrographic film equipment. Kodak also sells parts and provides services for its equipment. Kodak manufactures some equipment parts internally, while the remaining parts are ordered from independent original-equipment manufacturers (OEMs). There is no cross-compatibility of parts between Kodak’s equipment and its competitors’ equipment. In the 1980s, independent service organizations (ISOs) began selling parts for Kodak equipment and offering repair and maintenance services at much lower prices than Kodak. In response, Kodak began refusing to sell replacement parts to buyers who used ISOs for servicing Kodak equipment and also made it more difficult to obtain used Kodak equipment. Kodak also reached agreements with OEMs that prohibited the sale of equipment parts to anyone other than Kodak. As a result, many ISOs went out of business or lost significant revenue. Image Technical Services, Inc. (ITS) (plaintiff), representing a class of ISOs, brought a suit against Kodak for violating the Sherman Act. The district court granted Kodak’s motion for summary judgment, but the court of appeals reversed. Kodak appealed.