The American Express matter was an antitrust Restraint of Trade challenge under Section 1 of the Sherman Act, brought by the United States Department of Justice and the attorneys general of several states (collectively, the “Plaintiffs”) against American Express Company and American Express Travel Related Services Company, Inc. (collectively, “American Express”). The Plaintiffs challenged American Express’s “merchant restraints”—its rules barring merchants from steering customers toward lower-cost cards—as provisions that insulated American Express from competition and impeded price competition on card-acceptance fees. A central economic question was American Express's Market Power, and in particular whether American Express earned economic returns in excess of its cost of capital.
On behalf of the Plaintiffs, Mark E. Zmijewski—Professor Emeritus at The University of Chicago Booth School of Business—was retained to respond to the defendants' rebuttal expert, whose report concluded that American Express did not earn profits in excess of a normal competitive return on its card business. Professor Zmijewski was supported by Keith Bockus, Erik Himan, and Pavel Nikolov. His sur-rebuttal report evaluated the reliability of the rebuttal expert report's economic-return estimates for American Express’s U.S. and Australian card businesses and their comparison to American Express’s cost of capital.