Assault is a commonplace crime with uncommon potential for shedding light on the American criminal justice system. It lives on the periphery of American legal historiography, and yet, because of the ubiquity of small-scale violence, it has for centuries been a perennial and pesky nuisance threatening to overwhelm courts everywhere. Perched between private and public, criminal and civil, and bound to questions of governance and the rule of law, assault can no longer be ignored. Because of its nature as both a civil action and criminal offense, assault presents an opportunity to capture the evolving meanings of “public” and “private.” To what extent an assault was “criminal” hinged upon whether the “public” had an interest in the case, a criterion both amorphous and politically charged.1 At the time of William Blackstone's writing in eighteenth-century England, assault was criminal insofar as it constituted a breach of the public peace, an insult to the king, and a threat, by its “evil example,” to the public at large. By the 1850s, much had changed. Two major figures in American criminal justice law, Joel Bishop and Francis Wharton, declared that assault's status as a crime no longer depended upon some ineffable public harm. Rather, it was the individual injury to a member of the public that constituted its chief criminal component. But this individuated logic also meant that, barring sufficiently severe or shocking injury, newly empowered members of the public could be entrusted to sort out matters on their own. This article contends that a changing view of criminal justice—an underlying “public” transformed from a paternalistically governed, impressionable populace to a group of independent persons—gave violence a much wider legal legitimacy.