In an era when political leaders and policy advocates increasingly invoke humanitarian reasons to intervene around the world, the legality and underlying normative theory of humanitarian intervention spark heated disputes. On every major question, disagreement abounds among practitioners and commentators alike. Is humanitarian intervention ever permissible under international law? If so, within what range of factual circumstances or procedural conditions? Is it ever morally justifiable or even obligatory? If so, do the applicable theories of politics or human rights point to relatively expansive or restrictive views of the propriety of intervention? This essay reviews the disparate answers to these questions that come from several, mostly positivist, arguments about the legality of humanitarian intervention and various consequentialist and rights-based analyses of the morality of humanitarian intervention. An alternative model is derived from the American law and jurisprudence of the Good Samaritan. This Good Samaritan-based paradigm can provide the connections between legal and normative questions and a degree of constraint and determinacy that are lacking amid the current welter of divergent and competing claims.