Sexual abuse of children involves inappropriate sexual contact between a child and an adult or a much older child. According to a definition used by Joan Liem, Jacqueline James, and colleagues in a 1997 study, sexual abuse involves any form of coercive sexual contact with an under-age child or any sexual contact between a child thirteen years or younger and someone five or more years older. Although the exact statutes vary state by state, any adult sexual contact with an under-age child is against the law. Sexual abuse ranges from exposure of genitals to fondling of body parts to direct genital contact and, ultimately, to anal or vaginal intercourse. Arguably, sexual abuse may be the most psychologically damaging form of child abuse.