Dr Ronen's book deals with an important modern topic – how to move from an unlawful regime on the outer in international society to a secure, recognized society – normally a state member of the United Nations and of other international organizations. How to transition?

This is, of course, not just an issue of conflict management (though it is that), and the study is not just a detailed description of particular instances of transition (though it is that). For the focus of study raises the old question of the relationship between two broad elements underpinning international law, legality and effectiveness, as expressed in a discrete category of situations: transition from illegal territorial regimes under international law. Dr Ronen examines how the tension between the two elements informs the policy of post-transition regimes, in particular the extent to which they attempt to reverse the factual situation created by the preceding regime, and the extent to which they succeed, in light of the legal and political constraints in which they operate. These include the need to take account of the interests of third parties, as well as of international human rights law. On the basis of doctrinal analysis and a thorough review of practice, her study seeks to contribute towards a response to the more general question: how, and to what extent, the transition from an unlawful regime is substantively different from the ‘ordinary case’ of succession of states; and, further, whether the obligation of non-recognition is an effective tool of international legal enforcement.