@Reminiscence, even if there were laws on the books concerning child-on-child sexual assault, I'm not sure if incarcerating a minor in a juvenile detention facility would be the best way to go. A family court judge might decide to order intensive psychological therapy instead. It would be difficult to say if a minor could legally form "intent" to commit a sexual crime. You mentioned "playing doctor", which many people view as an innocent exploration of childhood sexuality. Child-on-child sexual assault would most likely require more proof of trauma in order to become a legal matter.