The case for U.S. health system reform aimed at achieving wider insurance coverage in the population and disciplining the growth of costs is fundamentally a moral case, grounded in two principles: (1) a principle of social justice, the Just Sharing of the costs of illness, and (2) a related principle of fairness, the Prevention of Free-Riding. These principles generate an argument for universal access to basic care when applied to two existing facts: the phenomenon of “market failure” in health insurance and, in the U.S., the existing legal guarantee of access to emergency care. The principles are widely shared in U.S. moral culture by conservatives and liberals alike. Similarly, across the political spectrum, the fact of market failure is not contested (though it is sometimes ignored), and the guarantee of access to emergency care is rarely challenged. The conclusion generated by the principles is not only that insurance for a basic minimum of care should be mandatory but that the scope of that care should be lean, efficient, and constrained in its cost.