Joint brief of the United States and the Federal Trade Commission, as amici curiae before the United States Court of Appeals for the Fourth Circuit, in support of vacatur and remand. The case involves the proper definition of the relevant geographic market in an antitrust counterclaim under Section 2 of the Sherman Act, 15 U.S.C. § 2, arising out of a trade dispute between the parties. The district court dismissed defendant’s counterclaim for failure to allege a proper geographic market, holding, as a matter of law, that a relevant geographic market in an antitrust case must be defined to include not only the locations of customers put at risk by the alleged anticompetitive conduct but also the locations of production for all supplies of the relevant product available to those customers. In their brief, the antitrust agencies urge the court of appeals to vacate the district court’s ruling and remand the case for further consideration of the sufficiency of defendant’s geographic market allegations under the proper legal standard.