The interaction between immunities and jurisdiction is complex. One lacuna is whether the international legal principle of state immunity is a rule or principle in its own right or an exception to a pre-existing jurisdiction. In the context of international arbitration disputes, this distinction is significant. States have been relying on immunity to exclude the jurisdiction of national courts to support the international arbitral process. This Article argues there is now a growing set of common and consistent practice according to which state immunity operates as a rule or principle lex specialis to a more general set of rules or principles governing the enforcement jurisdiction of national courts.