The aim of this contribution is to elucidate that the specific medico-legal trajectories - from arrest up to sentence execution - for mentally disordered suspects and offenders vastly differ across Europe. These major differences imply that harmonization of forensic regulations will be difficult, if not impossible, to achieve. In this context it is important to examine whether or not European cooperation instruments are adjusted to this specific category of suspects and offenders. It will also be demonstrated that the forensic reality is not only varied across Europe but often sub-optimal and therefore hampers the smooth and
adequate operation of European cooperation instruments. In addition, the contribution will also point to some inherent deficiencies of these instruments, having vast implications for the safeguarding of the research population’s (fundamental) rights. This contribution will be limited to a brief problem analysis and will not thoroughly touch upon potential remedies.