The Chapter analyses the scope of head of State immunity before international criminal courts. Although there seems to be quite a large consensus that immunities should not bar prosecution by international courts, doubts persist not only with regard to third parties. In the recent Kenyatta case, the African Union strongly argued in favour of granting immunity, although Kenya had ratified the Rome Statute of the International Criminal Court. The Chapter reviews relevant case law and then draws on Max Weber’s distinction between the ethic of principled conviction (Gesinnungsethik) and the ethic of responsibility (Verantwortungsethik) in order to explore the inherent tension between the interests of ex officio prosecution on the one hand and of political control on the other hand.