Article 27 UNCLOS

UNCLOS Article 27 governs criminal jurisdiction aboard a foreign ship passing through the territorial sea. The coastal state should not arrest any person or investigate a crime committed on board during passage, with four exceptions: the consequences extend to the coastal state, the crime disturbs the peace of the country or the good order of the territorial sea, the master or flag state requests assistance, or measures are needed to suppress illicit narcotics traffic. It also requires notifying a flag-state consular officer before any action.