This book explores the evolution of one of the main principles of sovereignty in public international law: non-intervention. Providing a framework to understand the main and current challenges to the centuries-old concepts of sovereignty and territorial sovereignty, the book covers topics such as self-determination, secession, and the use of force. Additionally, it highlights the transnational nature of cyberspace, and the challenges associated with its regulation and protection. This book explores newly emerging areas that invite intervention, such as the restoration of democracy, the right to gender freedom, the protection of human rights, global environmental issues and state-sponsored murder. ICJ decisions, and UNGA and UNSC resolutions, help illustrate how the principles of sovereignty and non-intervention have evolved. Constantly changing international legal norms arising from developments across multiple spheres continue to challenge the supremacy of sovereignty and its constituent components. These are no longer immutably determined doctrines; they must be flexible and receptive to the ever-evolving context in which they operate. In this way, the book challenges the traditional international relations approaches to the interpretation and application of sovereignty and non-intervention, arguing for a more fluid approach to reduce confrontational relationships among the various state and non-state actors and recognising the increasingly significant role of technology in this ever-evolving international legal environment. The book will be of interest to researchers in the field of public international law, sovereignty and international relations.