At the same time as it grew exponentially, investment arbitration started attracting increasingly vocal criticism especially about the lack of transparency, consistency and legitimacy. This course seeks to understand where investment arbitration comes from, what the profound reasons for the current critiques and concerns are, and why they are raised now. It then focuses on the reform initiatives that are presently ongling, be it through treaty drafting, rules amendments by institutions, such as ICSID, and most importantly through the UNCITRAL reform process. Should investment arbitration be abolished in favor of national courts, or mediation? Should it be replaced by an investment court? Or supplemented by a permanent appellate mechanism? Should it be simply improved? How? Answering these questions will allow to reflect on the purpose of international dispute settlement and on how to design a workable and fair justice system.