The deterrent and remedial power of civil litigation in U.S. courts is justifiably famous. But as Kiobel and other cases underscore, such litigation is only one of many possible ways to regulate harms that affect multiple sovereigns. Globalization, increased cross-border activity, and the lightweight limits on extraterritorial jurisdiction imposed by international law combine to create an environment in which it is common for multiple legal systems to regulate a single course of conduct. When sovereigns disagree over how to regulate harm, the ensuing conflicts expose U.S. legal systems to a new and unfamiliar form of political backlash. This Article identifies, explains, and critically analyzes a new body of law that responds to these conflicts in a novel and problematic way. Beginning in the 1980s and accelerating in recent terms, the Supreme Court has interpreted indeterminate legal materials that are not obviously about regulatory conflict to create a set of clear, ex ante rules restricting private regulatory enforcement in U.S. courts. This set of rules—”the new conflicts law”—prevents conflicts between domestic litigation and other nations’ approaches to regulating harm and transfers authority for regulatory conflict from frontline decisionmakers to the U.S. Supreme Court. But in seeking to limit interference with foreign regulation, the new law undermines U.S. regulatory systems with no clear welfare payoff. And it often precludes democratically accountable policymakers from revisiting the Supreme Court’s conclusions about the appropriate relationship between U.S. litigation and foreign regulation. To address these concerns, the Article proposes incremental changes to four doctrines within the new conflicts law. The more basic and urgent task, however, is to recognize the new conflicts law for the significant development it is. With little fanfare, the Supreme Court has dramatically changed the way in which the U.S. legal system manages regulatory conflict.