possession of firearms by felons. .. ." 1 The Heller Court did not elaborate on why such laws were presumptively lawful, instead promising to provide a "historical justification" for such laws when a better opportunity arises. 2 Two years later, the Court again referenced these presumptively lawful regulations in McDonald v. City of Chicago, but did not use the opportunity to elaborate on the historical basis for the regulations. 3 Thus far-over a decade since the Heller decision-the Court has not yet provided that historical justification. In the meantime, lower courts have been inundated with challenges to these presumptively lawful measures. The federal law prohibiting felons from possessing firearms has been the most challenged law under the Second Amendment post-Heller. 4 This Article surveys English and American history to discover what historical justification the Supreme Court was referring to. Part II examines what the Supreme Court has said about firearm prohibitions on felons. Section A explains why felon bans are presumptively lawful, Section B explains why the presumption of lawfulness is rebuttable, and Section C explains why any prohibition on felons must be rooted in history and tradition. Part III explores the history of laws prohibiting categories of people from possessing arms. Section A explores disarmament efforts throughout England's history. England had a long tradition of disarming dangerous persons, especially those disloyal to the government. Section B surveys laws from colonial America. Consistent with English tradition, colonial disarmament efforts focused on those perceived as posing a dangerous threat, including Loyalists to the British Crown, slaves, freedmen, and Native Americans. Section C summarizes the proposals from the ratifying conventions of Massachusetts, New Hampshire, and Pennsylvania. All three proposals are most reasonably read as allowing only dangerous persons to be disarmed. Section D provides examples of when prohibited persons could have their arms rights restored in the founding era. Unlike the lifetime bans that typically apply today, prohibited persons in the founding era could often regain their rights once they were no longer perceived as dangerous. Section E focuses on the nineteenth century, in which slaves, freedmen, and tramps were regulated most severely. Section F surveys the increasingly prevalent prohibitions in the twentieth century. The majority of these applied to noncitizens and are examined in Section F.1. The others applied to violent criminals and are examined in Section F.2.