Ohio v. American Express and the Balancing of Consumer Welfare Effects on Multiple Sides of a Platform

In Ohio v. American Express Co. the U.S. Supreme Court ruled that in the case of transaction platforms, a single relevant market must be defined, where both sides of the platform simultaneously consume the same good, namely, a transaction. Therefore, a plaintiff must show net overall harm to all sides of the market to satisfy its prima facie burden of proof. This case note argues that this rule is ill-suited to distinguish between procompetitive behavior and exercises of market power that can be justified with mere wealth transfers from one side of the market to the other. In line with an alternative allocation of the burden of proof proposed in the literature, this case note proposes a standard for evaluating countervailing benefits on all sides of the platform. Finally, the case note explains why the Court’s analysis of the effects of the anti-steering provisions was based on faulty economic grounds and the cherry-picking of facts on the record developed at the district court.