This book explores the evolution and internalization of regional international law in the Eurasian Russian context, covering historical, contemporary, and future perspectives. Providing a forward-looking analysis, the book makes predictions as to how emerging geopolitical and geoeconomic trends will influence the development of regional international law and the balance of power within the Eurasian region. Analysing perceptions of universalism and regionalism across various historical periods in Eurasia, the book focuses on what now encompasses the post-Soviet states, with wider lessons for the international legal community. The book discusses Russia's use of international law to sustain its geopolitical objectives and the subsequent responses from neighbouring states. Evaluating Soviet international law and its relationship with regionalism and universality, the book also explores post-Soviet Russia's efforts to redefine international law by creating its own vision of regional (Eurasian) international law through regional organizations such as the CIS, CSTO, and EAEU in the post-Soviet Eurasian space. Within the current context of Russia's 2022 invasion of Ukraine, it explores how the post-Soviet Eurasian states have navigated their legal and political landscapes amidst competing pressures from both regional and global actors. The book will be of interest to researchers in the field of international law, alongside Eurasian Russian politics.