["On hidden madness"--"De amentia occulta" by Ernst Platner in early 19th-century tension of medicine and jurisprudence].

During the first half of the 19th century psychiatry became more and more influential in the evaluation of mentally ill offenders. "Doubtful" states of mind gained a particular importance for forensic practice. One of the mental disorders that was heavily disputed was amentia occulta (hidden madness) first described by the well-known Leipzig doctor and philosopher Ernst Platner. This publication (1797) preluded several other diagnoses to refer to non-obvious, "hidden mental derangements". Regardless of the differences in arguments as developed by the experts in question (E. T. A. Hoffmann, Merzdorff, E. Horn, J. C. A. Clarus), two case studies from the early 19 (th) century (D. Schmolling, J. C. Woyzeck) will exemplify the process of medicine, and psychiatry in particular, becoming more and more influential in everyday jurisdictional practice. The above-mentioned Ernst Platner, the author of manifold forensic studies and of "De amentia occulta", was one of the pioneers and promoters of this process. By emphasising the importance of mental states being evaluated by medical professionals he contributed a great deal to the establishment of forensic psychiatry.