D owns and publishes the morning Times-Picayune and the evening States. Buyers of space for general display and classified advertising in its publications may purchase only combined insertions appearing in both the morning and evening papers, and not in either separately. Both papers were distributed in New Orleans, Louisiana. The Times-Picayune, the sole local morning daily outdistanced the States and Item, a second-afternoon paper, in circulation. The Item is the sole effective daily competition which the Times-Picayune Publishing Company's two newspapers. The United States (P) filed a civil suit under the Sherman Act, challenging these 'unit' or 'forced combination' contracts as unreasonable restraints of interstate trade, banned by § 1, and as tools in an attempt to monopolize a segment of interstate commerce, in violation of § 2. The District Court determined the adoption of unit selling caused a substantial rise in classified and general advertising linage placed in the States, enabling it to enhance its comparative position toward the Item. The court found that Ds had instituted the unit system, economically enforceable against buyers solely because of the Times-Picayune's 'dominant' or 'monopoly position,' in order to 'restrain general and classified advertisers from making an untrammeled choice between the States and the Item in purchasing advertising space, and also to substantially diminish the competitive vigor of the Item The contracts were viewed as tying arrangements. Injunctive relief was accordingly decreed. P appealed.