Teenagers represent a precisely circumscribed population amounting to one fourth of the total world population. They are individuals who are in the process of developing, and are consequently particularly vulnerable. The transition from childhood to adulthood is a pivotal period during which the foundations for the individual’s future health are laid. It is at this time that risk behaviours may emerge. Importantly, 70% of adult premature deaths occur as a consequence of risk behaviours that were acquired in adolescence. Transgression of the law is common theme in risk behaviour, and it often leads to the teenage perpetrators being taken into police custody. In France, the Criminal Procedure Code states that, as part of the judicial inquiry, a person aged 13 or over who is suspected of committing or attempting to commit an offense shall be placed in police custody. The number of minors placed into police custody in France has been growing steadily in the last few years, thus mirroring an increase in the number of adults in custody.