Relevant Generality of Antitrust Economics: Competitive Effects as Adjudicative and Legislative Facts

Antitrust enforcement proceedings routinely rely on information provided by positive economics. Recognizing that this information may help the court to decide what happened in the case at bar as well as what substantive rule to apply to the case, this article examines how general the information needs to be to bear relevance to each of these decision-making tasks. The examination is conducted in the context of US law, relies on the conventional distinction between adjudicative and legislative facts, and focuses on competitive effects as the paramount type of antitrust facts. Economic inquiries into the competitive effects of the conduct under scrutiny are then shown to be relevant if they take sufficient account of the specifics of the case. This requirement will rarely be satisfied by inquiries based on generic models. In contrast, when deciding on the content of the applicable antirust rule, the court needs comprehensive information about the competitive effects of the entire conduct class. Economic analyses into the effects of specific conduct will hence be hardly relevant.