Legal history of emergency medicine from medieval common law to the AIDS epidemic.

The early development of legal obligation in emergency medicine is traced through medieval English common law to the first stages of American law after Independence. An identifiable set of legal principles in the nineteenth and early twentieth centuries is described. The movement away from an absence of legal and ethical duties to answer any emergencies, or to offer any emergency services in hospitals, toward a growing demand for access to emergency services in the middle decades of the twentieth century is reviewed. The enactment of Good Samaritan Laws is described, along with other federal and state law reforms. In the modern era, there has been a substantial legal and ethical change to a requirement of extensive duties to operate open-admission emergency services in virtually all acute-care hospitals. The AIDS epidemic is utilized as a case example of expanded legal and ethical duties to offer emergency care in a nondiscriminatory manner to all patients presenting at hospital emergency departments.