In this paper I examine the ways in which the concept of “public interest” is used in biomedical policymaking to justify the preemption or overruling of decisions made by individuals about their own, their family's, or group interests in the field of healthcare. I discuss six variants of public-interest justification, before going on to consider a concrete example, the use of personal health data in health services management and medical research. I distinguish between the global public interest and particular public interests and consider critically how the global public interest can be said to arise from private interests. I show that there is always room for the private individual to defeat appeals to public interest on moral grounds, and hence that public interest cannot have overriding moral force. Hence, public-interest claims need to be considered as political appeals about competing claims and conceptions of justice, rather than as shortcuts to defining the universal solidary interest.