Two central goals of health policy are to improve population health as much as possible and to distribute the improvements fairly. These goals will often conflict. Reasonable people will disagree about how to resolve these conflicts, which take the form of various unsolved rationing problems. The conflict is also illustrated by the ethical controversy that surrounds the use of cost-effectiveness analysis. Because there is no consensus on principles to resolve these disputes, a fair process is needed to assure outcomes that are perceived to be fair and reasonable. One such process, accountability for reasonableness, assures transparency, involves stakeholders in deliberating about relevant rationales, and requires that decisions be revised in light of new evidence and arguments. It has been influential in various contexts including developed countries such as Canada, the United Kingdom, New Zealand, and Sweden, and developing countries, such as Mexico....