The Copperweld doctrine treats separate corporations that are subject to substantially common ownership and function as an economic unit as a single entity that cannot form an intra-enterprise combination or conspiracy that violates the antitrust laws. Here, however, the plaintiffs alleged that a corporation and its subsidiary corporation formed a conspiracy with wholly unrelated corporations. In that context, the Copperweld doctrine affords neither the corporation nor its subsidiary any immunity from antitrust liability.
Ninth Circuit Court of Appeals (Bea, J.); August 6, 2018; 2018 U.S. App. LEXIS 21699