The Act of state doctrine essentially serves to truncate or end proceedings against a state in the court of another state for actions attributed to or owned by the first state. Originally, the actions against which the defense could be raised were wide and all encompassing. It included exercise of police powers, takings, maritime and commercial acts. However, starting with cases such as Bernstein, Dunhill and others, and goaded in part by legislation such as the second Hickenlooper Amendment in the US, a number of exceptions have been carved into the doctrine. It is such that some academics have called for the end of the doctrine. This paper argues that although the doctrine is now limited, compared to its original compass, it is resilient. That resilience, this paper contends, is predicated on its International law pedigree. It is further argued that the swings in the role of the state in economic matters accounts for the growth, downturn and upturn in the viability of the doctrine as a defense in international economic law.