More salient in the era of Covid-19, the question of physicians’ obligations to safeguard the health of non-patients continually vexes courts, scholars, and policymakers. Physicians’ public health duties are confoundingly elusive. Elusive in the sense that while at times affirming physicians’ special capacity and obligations to improve the health of the community, the law more often obscures physicians’ public health duties with ad hoc recognition and insufficient theorization. These public health duties also are elusive in actual application. Physicians can point to individual patient duties as reasons to evade compliance with certain public health laws or to discount public health considerations in clinical decision-making. As a matter of health policy, the law’s directive to “put patients first” has underappreciated costs. It frequently overrides physicians’ more elusive public health duties in ways that facilitate externalization of health risks to the public. This paper analyzes the Covid-19 pandemic, antibiotic resistance, infectious disease reporting, the opioid crisis, and gun violence as disturbing examples. Amplifying physicians’ public health duties to require that they pay greater heed to the population’s health, even to the detriment of doing all possible for their individual patients, seems unavoidably necessary. The nation’s public health system largely depends upon non-governmental actors, and private physicians are at the center of this public/private response. The private physician occupies a unique strategic role embedded between her patient, other patients, and society and performs critical sentinel, gatekeeper, and learned intermediary functions that are indispensable to effective public health protection.