Patients' rights need to be protected, particularly if the patient is unconscious or otherwise unable to consent. According to German law, a legal proxy is mandatory. Spouses and adult children do not automatically function as legal proxies. There are two alternative ways to become a legal proxy: a patient representative (Bevollmächtigter) is authorized by a written power of attorney (Vorsorgevollmacht), signed by the patient. If there is no power of attorney, a legal guardian (Betreuer) has to be appointed by a guardianship court. Both representatives and guardians are obliged to support the patient and are only allowed to make medical decisions, if the patient is currently unable to give his/her consent. The legal proxy is obligated to take into account advance directives, other patient preferences and presumed wishes. Recommendations and examples are given on how to apply these documents in medical practice and how to deal with legal representatives and guardians.