The ultimate test of whether an association is voluntary or not is if you can leave it. It is difficult, at this remove, to appreciate how live an issue secession from the British commonwealth of nations was in the 1920s and 1930s. It occupied an inordinate amount of time and negotiation for a doctrine that had been ostensibly conceded in 1920. Yet, much as with the case of the appeal to the judicial committee of the privy council, once the dominions sought to take advantage of the freedom which had been guaranteed by official statements, they found a formidable amount of diplomatic pressure and legal opinion brought to bear to indicate that no such right could be officially declared. This article traces the evolution of the arguments about the right to secede in the 1930s, and examines how the right came eventually to be exercised in the case of the new commonwealth countries in the 1940s. It concludes by examining how the doctrine of secession as developed in the 1930s was abandoned in order to retain Indian membership in the commonwealth.