It is legally required to determine and respect patient preferences and wishes as much as possible under the circumstances given. This also applies to emergency medicine and intensive care, particularly if a patient is unconscious and is not able to give his consent by him-/herself. According to German law, patients' explicit written statements (advance directive, living will) are mandatory. If no advance directive is available, or if the directive does not match the current medical circumstances, other (oral) statements of the individual patient have to be scrutinized to identify presumed wishes and establish presumed consent. Such wishes are equally binding. The article explicates the role of legal proxies (legal guardians, patient representatives) in determining patients' wishes. Detailed instructions and recommendations are given to medical staff on how to support legal representatives and next of kin with respect to shared decision-making and the process of determining patient preferences. This way, patient autonomy and patients' rights can be protected best.