Abstract
Ethical issues that can arise in distinguishing public health research from practice are highlighted in 2 case studies--an investigation of a tuberculosis outbreak in a prison and an evaluation of a program for improving HIV prevention services. Regardless of whether such public health investigations represent research or practice, we see a need for ethics oversight procedures that reflect actual risks and enable timely responses to crises. Such oversight should accommodate the perspectives of persons and communities affected by public health threats and by governmental responses to those threats; it should further recognize that public health ethics is a distinct field combining bioethics, political philosophy, human rights, and law.