The French parliament in August 2004 passed a law “concerning public health policies,” labeled by its authors as the “first” public health law since 1902. Grounded in the sociology of Abbott, our analysis, based on documentary sources and interviews both with participants in the law’s construction and with knowledgeable observers, shows that the motives for this law were complex. It was a marker laid down by a new health minister in a competition between professional epidemiologists and administrative elites about what “public health” should be and do. It was intended to mobilize the French population to more actively engage in preventive health behaviors, thereby (by implication) reducing the costs of medical care. It was an opportunity for a new health minister to put his name on a law, on a par with the loi Veil and the loi Evin. We conclude by commenting, first, on what has become a characteristic pattern in France of public health laws created “top-down” by tiny elite networks, and, second, on the question of how public action is legitimated in a neoliberal environment.