Examples of patients with anorexia nervosa, depression or borderline personality disorder who have decision-making capacity as currently operationalized, but refuse treatment, are discussed. It appears counterintuitive to respect their treatment refusal because their wish seems to be fuelled by their illness and the consequences of their refusal of treatment are severe. Some proposed solutions have focused on broadening the criteria for decision-making capacity, either in general or for specific patient groups, but these adjustments might discriminate against particular groups of patients and render the process less transparent. Other solutions focus on preferences expressed when patients are not ill, but this information is often not available. The reason for such difficulties with assessing decision-making capacity is that the underlying psychological processes of normal decision-making are not well known and one cannot differentiate between unwise decisions caused by an illness or other factors. The proposed alternative, set out in this paper, is to allow compulsory treatment of patients with decision-making capacity in cases of an emergency, if the refusal is potentially life threatening, but only for a time-limited period. The argument is also made for investigating hindsight agreement, in particular after compulsory measures.