Seventeenth century England saw major theoretical and legal innovations in how political community, sovereignty, and violence were understood—occasioned in significant part by two civil wars in the 1640s and 1680s. In my dissertation, I call attention to an important theme running through many of the major political and legal theoretical treatises, political pamphlets, and popular literature of the period that identifies criminality with the pirate (or his land-based equivalent, the highwayman), and punishment with war. My project begins by drawing a contrast between English natural law thinkers and two of their significant Scholastic predecessors. Whereas for the Scholastics membership had been a precondition of punishment, Hugo Grotius, Thomas Hobbes, and John Locke instead embraced a natural right to punish and a view of the commonwealth as founded upon, rather than giving rise to, the ius gladii or right of blameless violence. Although in some respects these thinkers, along with Alberico Gentili, were engaged in an intellectual project meant to distinguish civil punishment from war outside the commonwealth’s borders, this natural right to punish and a justificatory account of punitive violence tied to an offender’s loss of status ended up reproducing extralegal violence within the commonwealth in Hobbes’s Leviathan and Locke’s Second Treatise of Civil Government. This theoretical tendency has a parallel in the popular identification of the pirate—the hostis humanis generis, or enemy of all mankind—with the highwayman in England during this period. The highwayman, like the pirate, disrupted trade routes by which a nascent English state attempted to project political power and was both an important figure for seventeenth century accounts of crime and punishment, and early efforts at public policing and prosecution. Treason, the subject of most public prosecutions of the period, also underwent a subtle but significant shift between the English Civil War and the Glorious Revolution. Where in the first part of the seventeenth century treason was crime of betrayal against the sovereign, by the 1680s it was increasingly understood as a threat to the status quo and security of the political community. Thus, I argue, the model for the “ordinary” adversarial criminal trial, which has its origins in the Treason Reform Act of 1696, is grounded in a theory of wrongdoing as existential threat. The idea of the “criminal” in English political and legal thought reflects an internalization of concepts associated with war.