Some argue that the concept of medical need is inadequate to inform the design of a universal health care system—particularly an institutional rather than a residual system. They argue that the concept contradicts the idea of comprehensiveness; leads to unsustainable expenditures; is too indeterminate for policy; and supports only a prioritarian distribution. I argue that ‘comprehensive’ understood as ‘including the full continuum of care’ and ‘medically necessary’ understood as ‘prioritized by medical criteria’ are not contradictory, and that UHC is a (...) solution to the problem of sustainability, not its cause. Those who criticize ‘medical need’ for indeterminacy are not transparent about the source of their commitment to their standards of determinacy: they promote standards that are higher than is necessary for legitimate policy, ignoring opportunity costs. Furthermore, the indeterminacy of concepts affects all risk-sharing systems and all systems that rely on medical standard of care. I then argue that the concept of need in itself does not imply a minimal sufficientist standard or a prioritarian distribution; neither does the idea of legitimate public policy dictate that public services be minimalist. The policy choice for a system of health care that is comprehensive and offers as good care as can be achieved when delivered on equal terms and conditions for all is a coherent option. (shrink)