P operates a retail store next to one of D's stores. D has a chain of department stores. P and D compete in the sale of radios, television sets, refrigerators, and other household appliances. P claims that manufacturers and distributors of such well-known brands as General Electric, RCA, Admiral, Zenith, Emerson and others have conspired among themselves and with D either not to sell to P's or to sell to it only at discriminatory prices and highly unfavorable terms. P claims that D has used its 'monopolistic' buying power to bring about this situation. At trial, D did not dispute these allegations but sought summary judgment and dismissal of the complaint for failure to state a cause of action. They showed that there were hundreds of other household appliance retailers, some within a few blocks of P who sold many competing brands of appliances, including those Ds refused to sell to P. D then claimed that the public had not been harmed by any agreement amongst Ds. The Court concluded that the controversy was a 'purely private quarrel' and not a 'public wrong proscribed by the Sherman Act.' The complaint was dismissed, and summary judgment was entered for Ds. The Court of Appeals affirmed the summary judgment. It stated that 'a violation of the Sherman Act requires conduct of defendants by which the public is or conceivably may be ultimately injured.' The Supreme Court granted certiorari.