This dissertation theorizes the political productivity of notions of universal crime as they circulated and continue to circulate in European political debates on the legitimacy of European coercive interference in non-European spaces. By the notion of universal crime, I mean the idea that certain locally committed acts violate universally valid norms and thereby not only injure their immediate victims, but also deeply offend humanity at large. In this thesis, I analyze how notions of universal crime give rise to modes of normative inclusion, political authority, and the legitimacy of foreign intervention in the history of European political thought. This analysis yields one theoretical and one historical argument. Theoretically, I argue that the notion of universal crime provides a kind of normative inclusion to the offender that is universal in scope and minimal in degree. Since the notion of criminality is internal to a preexisting normative order, the criminal against humanity is positioned within the global normative order. I suggest therefore that the 'criminal against humanity' is a figure distinct from the 'enemy of humanity' and that criminality offers an alternative principle to enmity in international politics. The historical argument accounts for the rise and fall of notions of universal crime in political discourses over time. I contend that notions of universal crime circulate in theoretical texts when ambiguities about sovereignty as a globally valid ordering principle promote a reliance on universal values to assess questions of legitimacy in global politics. Universal norms, such as humanitarian ethics, provide normative guidance in times in which the lack of clear conceptions of state sovereignty reduces its efficacy as a global ordering principle. I develop these arguments in three case studies in the history of European political thought in global context. These cases span John Locke's discussion of European colonialism in America, nineteenth century justifications of European imperialism, and Jürgen Habermas's cosmopolitan interpretations of military interventions in non-European polities during the twentieth and twenty-first centuries.