Dentsply International, Inc. is one of thirteen manufacturers of artificial teeth for use in dentures and other restorative appliances, which it sells to dental products dealers. The dealers then supply the teeth and various other materials to dental laboratories, which fabricate dentures for sale to dentists. Dentsply enjoys a 75 to 80 percent market share on a revenue basis, has a 67 percent share on a unit basis, and is about fifteen times larger than its next largest competitor. There are hundreds of dealers who compete on the basis of price and service among themselves, as well as with manufacturers that sell directly to laboratories. There are 16,000 dental laboratories that fabricate restorations, of which 7,000 provide dentures. These laboratories also compete with each other on the basis of price and service. When laboratories cannot supply the necessary teeth, dealers may fill orders for walk-ins or use overnight express mail, as does Dentsply.

In 1993, Dentsply adopted Dealer Criterion 6, which provides that in order to effectively promote Dentsply–York products, authorized dealers “may not add further tooth lines to their product offering.” Dentsply operates on a purchase order basis with its distributors and enforces Dealer Criterion 6 by terminating dealers who purchase from manufacturers (other than those “grandfathered” in pursuant to the policy). The U.S. Government alleged that Dentsply had acted unlawfully to maintain a monopoly in violation of Section 2 of the Sherman Act. How would the Government define the relevant market? How would Dentsply define the relevant market? What other arguments might Dentsply assert in its defense? Which party should prevail? [UnitedStates v. Dentsply International, Inc., 399 F.3d 181 (3d Cir. 2005), cert. denied, 546 U.S. 1089 (2006).]