This article merely outlines the methods of Teylingereind with respect to youth and young adult suspects who are difficult to examine, based on five cases. By collecting and combining data about this group from a range of different perspectives, better insight about the specific person was obtained in each of the cases as described. When it is possible to describe specific behavioural patterns, statements could be made about freedom of behavioural choices, danger of recidivism, and advice about the most appropriate legal framework. In this way, when there are serious concerns about the developmental course of youth and young adults who are not willing to cooperate in diagnostic research pro Justitia, clinical observation is of added value to the judge.