U.S. federal courts are increasingly hearing federal- and state-based antitrust cases together. This trend, hastened by the Class Action Fairness Act of 2005, offers significant opportunities to litigants and courts alike. Consolidation can streamline the resolution of federal and state claims arising out of similar facts, and can promote judicial efficiency in an overburdened system. But these opportunities also jeopardize constitutional due process rights — unless judges carefully ensure that each case’s trial structure preserves them. In the pursuit of judicial efficiency, due process must remain paramount.