Southeast Asia is sub-region of Asia that consists of 11 countries that spread out from the eastern China to India and are so rich in religion, culture, and history diversities. Ten of the 11 countries are members of the Association of Southeast Asian Nations (ASEAN). In terms of economy, most of them are within the World Bank classification of lower-middle income economies. Although classified as the lower-middle income economies, Southeast Asian countries have been praised as having buoyant economies, healthy investment, and growing trade ties. These economic potentials are in conjunction with the dynamic political sphere in the Southeast Asian countries. Recent increasing confrontation between China and the U.S. have also created the geopolitical uncertainty which threatens the economic growth in the region. All these economic and political events in the region are closely related to international law since they are dealt with legal entities beyond their own jurisdiction. This book would discuss various contemporary issues of international law that occurred in or related to countries located in the Southeast Asian region. There are 9 articles in this book. The articles would exhibit the relationship of international law and national law