Raison d'état (much less frequently in the English reason of state) dates from arguments in international law at the time of the formation of the modern states-system in the seventeenth century. It means that there may be reasons for acting (normally in foreign policy, less usually in domestic policy) which simply override all other considerations of a legal or moral kind. Raison d'état is thus a term which fits easily into the language of political realism and realpolitik. As those doctrines have declined in acceptability the term raison d'état declined with them.
— Peter Byrd
