Moving into 2012, U.S. antitrust enforcement agencies can be expected to continue their increasing focus on efforts by companies with large market shares to force customers or suppliers into exclusive dealing arrangements that foreclose rivals, or potential rivals, from the market. Several recent and pending agency cases have centered on allegations that a dominant firm has violated Section 2 of the Sherman Act by imposing onerous restrictions on the ability of its vertical partners to deal with rivals.

These cases are not unprecedented, but the renewed efforts to challenge this type of conduct highlight the fact that, although there is no such thing as conduct that is “per se” unlawful under Section 2, which prohibits illegal efforts to preserve or acquire a monopoly, these situations come as close as anything to the heart of the U.S. antitrust enforcement agenda in terms of unilateral-conduct cases....