In 1976, a group of dentists in Indiana formed the Indiana Federation of Dentists (the Federation) (defendant) and began a policy of ignoring requests from dental-insurance companies for the X-rays of patients. Dental insurers had been using X-rays to determine the cheapest adequate treatment for patients, and the Federation viewed this practice as a danger to the autonomy and ability of dentists to succeed financially. In 1978, the Federal Trade Commission (FTC) (plaintiff) brought a complaint against the Federation, alleging that the collective practice of withholding X-rays eliminated competition among dentists regarding policies for dealing with insurers. The FTC concluded that the practice was an unreasonable restraint of trade in violation of the Sherman Act. The Federation appealed the decision, and the court of appeals reversed. The FTC appealed.