Since 2013, the German Civil Code has had its own chapter on the treatment contract between doctor and patient. It sets the standard in one sentence: Die Behandlung hat nach den zum Zeitpunkt der Behandlung bestehenden, allgemein anerkannten fachlichen Standards zu erfolgen, soweit nicht etwas anderes vereinbart ist. Treatment must follow the generally recognized professional standards at the time of treatment, unless something else has been agreed. A doctor may use another method. But he must agree it with the patient.