In light of serious resource constraints, international criminal courts are required to select a small number of crimes for prosecution, leaving others to national courts or, more often, impunity. In recent years, feminists have advocated that such courts give priority to prosecuting sex crimes even at the expense of other serious crimes, including those involving killing. Many international prosecutors have heeded this call, placing special emphasis on the prosecution of sex crimes. At the same time, empirical evidence shows that many people consider sex crimes less serious than crimes resulting in death. There is thus a need to ground the selection of sex crimes for prosecution in the purposes of international criminal law. This essay examines the four primary philosophical bases advanced for international prosecutions – retribution, deterrence, expressivism, and restorative justice – to determine how they inform decisions whether to give priority to sex crime prosecutions. It concludes that retribution and deterrence support such selections at least some of the time, and expressivism and restorative justice provide an even stronger foundation for giving priority to sex crimes.