[The assessment of (in)competence to make a will].

Based upon German law and jurisdiction, psychiatric literature as well as the author's experiences, essential criteria for the assessment of testamentary capacity are presented, peculiarities of the posthumous assessment of psychopathology are explained and the anachronistic idea of the "lucid interval" is critically discussed. The legal term "freedom to determine one's will", decisive for the competence to contract and to make a will, corresponds to the psychopathological dimension of judgement. In the practice of experts' assessments, this criterion is most likely to be impaired by delusional misinterpretation of reality, lack of insight in being ill, pathological dominance of affects or suggestibility, while cognitive deficits are less often decisive. Using knowledgeably all available sources of information, a posthumous expert's statement on the legal ability to make a will is possible with the reliability legally required in more than 90 % of cases.