The provisions of Section 630 of the German Civil Code (BGB) on the so-called treatment contract are authoritative for consent to medical treatment. Treating physicians are obliged to inform patients in particular about the nature, implementation, risks and necessity of treatment. The treatment may only be performed if the patient consents after receiving this information. Information and the requirement of consent are aimed at protecting the patients' self-determination. In line with the principle of informational self-determination and the resulting right not to know, patients, but not those providing treatment, can waive the information requirement. This does not affect the requirement of consent. 

The ability to consent is legally defined as the ability of the patient to understand the nature, meaning and scope of the treatment in basic terms. The extent to which dementia sufferers are able to consent is not determined in general terms, but on basis of the facts of the case at hand. 

If a patient is unable to give consent, e.g. due to advanced dementia, "the consent of a party entitled to do so is to be acquired unless a living will [...] permits or prohibits the measure." (Section 630d(1), sentence 2). Exceptions are treatments that cannot be postponed in case of necessity as justification.