The Rome Statute in its Article 7 states that rape and other forms of sexual violence are Crimes against Humanity.
Crimes against Humanity are offences that constitute to a serious attack on human dignity or grave humiliation or a degradation of one or more human beings. They are not isolate or sporadic events, but are part either of a government policy (although the perpetrators not identify themselves with this policy) or of a wide practice of atrocities tolerated or condoned by a government or de facto authority.
Crimes against Humanity include Extermination, Enslavement, Deportation or Forcible transfer of population, Imprisonment or other severe deprivation of physical liberty in violation of fundamnetal rules of International Law, Torture, Rape, Sexual slavery, Enforced prostitution, Forced pregnancy, Enforced sterilisation or any other form of Sexual Violence of comparible gravity, Enforced disappearance of persons..
And it includes ”other Inhuman Acts of similar character intentionally causing Great Suffering or Serious Injury to body or to Mental or Physical Health”.