This work was created in cooperation with the Ludwig Boltzmann Institute and to legal problems that go along with the forensic examination of living persons explain. The forensic medical examination in living persons has made considerable progress in recent years and gained importance. In the present work will be discussed at the forensic medical examination in understanding and discernment incompetent persons. This is primarily to make a criminal assessment of forensic treatment and to clarify when a forensic medical examination must be performed. Following this, the "consent" explained. It should be noted that the consent is a complex legal phenomenon. She throws namely both criminal and civil law on issues. In particular, in the context of understanding and discernment incompetent persons, the "consent" be a problem, since they, unlike, for example, the capacity can be no rigid legal framework. Finally, in the present work will be explained, as experts and legal guardian may agree for understanding and discernment incompetent persons in a legal medical treatment. To be illustrating the theoretical statements using a practical example at the end of work.