The recent increased prevalence of diseases related to unhealthy lifestyles raises difficulties for health care insurance systems traditionally based on the principles of risk-management, solidarity, and selective altruism: since these diseases are, to some extent, predictable and avoidable, patients seem to bear some responsibility for their condition and may not deserve full access to social medical services. Here, we investigate with objective criteria to what extent it is warranted to hold patients responsible for their illness and to sanction them accordingly. We ground our analysis on a series of minimal conditions for “practical” and for “moral” responsibility attribution. By applying these criteria consistently, we highlight that individual responsibility applies to risk-taking life choices rather than stigmatizsed sickness. We explain that responsibility is a matter of degree, that it varies across life-history, and can be affected by factors beyond the independent of patients' grasp. We point out that scientific knowledge about the effect of these factors generates responsibilities for other parties such as public health agencies and private industry. The upshot of our analysis is that health policies targeting the “liable” undeserving sick are mostly unwarranted, and tend to increase unequal treatment of already vulnerable groups: the unlucky sick