The international law of foreign investment is one of the fastest growing areas of international economic law and policy which increasingly rely on large membership investment treaties such as the ASEAN Comprehensive Investment Agreement (ACIA). This book comprehensively examines the role of this specific international treaty on investment and situates it in the wider global trend towards the regionalisation of laws and policy on foreign investment. Considering the state of the ASEAN Economic Community in 2015 and its transformation until 2025, Julien Chaisse and Sufian Jusoh illustrate the pivotal role ACIA has to play in future international investment law negotiations and the benefits to ASEAN and third country investors and their investments. Collective commitment to a common standard contributes to depoliticise any potential conflict between individual investors and host states, making the agreement particularly crucial to discussions involving ASEAN Member States and between ASEAN and Dialogue Partners as well as to investment decisions including investment liberalisation and investment facilitation. Offering the first detailed analysis of ACIA and its applications, this book will prove essential reading for legal practitioners in the field of international investment law as well as researchers and students studying the ASEAN Economic Community and its contemporary moulding.