Despite increased calls for hospital ethics committees to serve as default decision-makers about life-sustaining treatment for unrepresented patients who lack decision-making capacity or a surrogate decision-maker and whose wishes regarding medical care are not known, little is known about how committees currently function in these cases. This was a retrospective cohort study of all ethics committee consultations involving decision-making about LST for unrepresented patients at a large academic hospital from 2007 to 2013. There were 310 ethics committee consultations, twenty-five of (...) which involved unrepresented patients. In thirteen cases, the ethics consultants evaluated a possible substitute decision-maker identified by social workers and/or case managers. In the remaining cases, the ethics consultants worked with the medical team to contact previous healthcare professionals to provide substituted judgement, found prior advance care planning documents, or identified the patient’s best interest as the decision-making standard. In the majority of cases, the final decision was to limit or withdraw LST or to change code status to Do Not Resuscitate/Do Not Intubate. Substitute decision-makers who had been evaluated through the ethics consultation process and who made the final decision alone were more likely to continue LST than cases in which physicians made the final decision. In our centre, the primary role of ethics consultants in decision-making for unrepresented patients is to identify appropriate decision-making standards. In the absence of other data suggesting that ethics committees, as currently constituted, are ready to serve as substitute decision-makers for unrepresented patients, caution is necessary before designating these committees as default decision-makers. (shrink)