A daily reality in hospitals and a task that most often falls to family members is making choices for patients who lack decision-making capacity. Referred to as proxies or surrogate decision makers, these individuals are expected to make decisions that accord with what patients would have wanted if they had been able to decide for themselves. In clinical practice, when patients lose decisional capacity, surrogates are asked to apply a hierarchy of three ethical standards based on the principle of autonomy: (1) known wishes, (2) substituted judgment, and (3) best interests. However, mounting empirical research indicates that surrogate decisions are not always consistent with the patients’ wishes. This 3-standard hierarchy may not account for all of the factors that surrogates consider when making decisions on behalf of a loved one. The purpose of this article was to examine five assumptions about surrogate decision making that are implicit in the three-standard hierarchy. We then apply a moral psychology perspective to offer explanations about why surrogates may make decisions that conflict with this framework. Implications for practice and research are suggested to assist clinicians and researchers to develop appropriate interventions to support surrogate decision makers in this common yet difficult task.