Helmut Philipp Aust’s topic is the connection between foreign relations law and domestic conceptions of democracy, and in particular the question of ‘who gets to decide on the international commitments of a state?’. Populism and a broader inward–turn in the politics of many Western states, Aust writes, mean that ‘there is a growing level of discontent with the way that the external sphere is impacting on the internal’. These changing perceptions of ’the international’ filter through into different conceptions of foreign relations law, which, in turn, affect the ability of states to cooperate internationally. The chapter presents two variants of foreign relations law – a ’closed’ version prevalent in the USA, and a German version traditionally more open to international cooperation. Through a comparative analysis, Aust shows how the openness to international cooperation that was long seen to lie at the heart of the German Basic Law, is coming under increasing pressure.