How can the international community respond to States that fail to respect fundamental rules of international law? Does a State that collapses into anarchy lose its sovereignty? Finding answers to these questions requires a reconsideration of what constitutes the core of present-day international law. State sovereignty has always been regarded as the backbone of international law but is its importance now diminishing? In order to shed some light on these issues, the editors have brought together a number of leading authorities and up-and-coming young scholars to reflect on these questions, and in particular on the question of the role of State sovereignty in present-day international law.