The use of restraint in hospital settings is divisive, and internationally there are calls for its elimination. However, this is at odds with the experience of many hospital staff, who consider restraint, at times, a “necessary evil”. In this paper, we explore the definition of restraint and potential ethical justifications for its use. We argue that the current ethical literature employs two definitions of restraint — outcome-oriented and intent-oriented — neither of which successfully captures all ethically relevant features of the practice. We propose a new conceptualization of restraint which centers on the number of individuals impacted by an act of patient restraint — a continuum between therapeutic restraint and public-safety restraint. Understood in this way, neither the principlist nor human rights frameworks that dominate the current literature are appropriate for assessing the ethical legitimacy of restraint. We suggest that, given the similarities between restraint and public health interventions, the use of public health ethics principles to consider the ethical justifiability of restraint in hospitals is a potentially productive way forward in this controversial area.