In Switzerland, forensic psychiatric assessment is a legally defined prerequisite for a trial, if the judges are in doubt about the defendants mental healthiness. In every such case assessment of criminal responsibility and prognosis is mandatory. The Swiss law knows since long the preventive and temporally limitless detention of mentally ill offenders, if their mental state and therefore their dangerousness cannot be ameliorated by means of therapy. Actually around 130 mentally ill offenders are under preventive detention, with an additional 12 every year. In 1993 a Swiss prisoner, sentenced for two cases of sex murder and several cases of rape, killed during his unattended free weekend trip a young girl. As a consequence committees reviewed procedures for risk assessment and decisions about release in high risk offenders, finding important shortcomings. In 1996 commissions for the assessment of offenders dangerous to the public began their work and a catalogue for risk assessment was defined. These commissions do not take decisions, they only advise responsible authorities upon their request. Since the introduction of those commissions, no severe reoffences occurred in any of the cases reviewed. For risk assessment the commissions use an instrument called “Catalogue for risk assessment in offenders dangerous to the public” witch was developed in Basel. This catalogue is rather a toolbox, not an instrument to measure dangerousness. With this method a systematic and standardized assessment between cases and over time is ensured.