In 1981, Dr. Simon J. Pinhas (plaintiff) was employed as an eye surgeon on the staff of Midway Hospital Medical Center (Midway) (defendant), which was located in California and owned by Summit Health, Ltd. (Summit) (defendant). In 1986, the Medicare program announced that surgeons would no longer be reimbursed for the services of assistants. After the announcement, most of the hospitals in Southern California abandoned the practice of using an assistant surgeon. However, Midway continued to require an assistant surgeon for eye surgeries. As a result, Pinhas was personally obligated to pay for the services of an assistant. Pinhas advised Midway that he would quit if the requirement was not eliminated. Midway initially offered Pinhas a sham contract that would account for his out-of-pocket costs without increasing his obligations, but Pinhas refused. Midway then initiated a peer-review proceeding against Pinhas, which was carried out unfairly by a group of biased participants. Pinhas’s staff privileges at Midway were terminated, and Midway was preparing to send out a negative report of Pinhas that would make it very difficult for Pinhas to obtain employment as an eye surgeon. In response, Pinhas filed a complaint against Summit, Midway, and Midway’s medical staff, alleging that the defendants had engaged in a conspiracy to reduce competition in violation of § 1 of the Sherman Act. The district court dismissed Pinhas’s claim, but the court of appeals reinstated the antitrust claim on Pinhas’s appeal.