Once the ‘popular plaything of Realpolitiker’ the doctrine of rebus sic stantibus post the 1969 VCLT is often described as an objective rule by which, on grounds of equity and justice, a fundamental change of circumstances may be invoked as a ground for termination of a treaty. Yet recent practice from some States suggests that it is returning with a new livery. They point to an understanding that is premised on vital State interests––a view popular among scholars such as Erich Kaufmann at the beginning of the last century.