In Khurts Bat, the English High Court held that Mr Bat, a Mongolian State official charged with committing municipal crimes on German territory, was not immune from the jurisdiction of German courts and could therefore be extradited to Germany. This article examines the three theories of immunity put forward in that case: (1) special missions immunity, (2) high-ranking official immunity, and (3) State immunity. It focuses on the question of whether State officials charged with municipal crimes may plead immunity ratione materiae from the criminal jurisdiction of a foreign State by examining key examples of State practice.