Any assessment of the international investment regime and its legitimacy crisis requires a preliminary understanding of their important and relevant features. However, the sprawling nature of both defies most doctrinal and qualitative attempts at description. The regime is based on a decentralized network of legal instruments, different procedural mechanisms and ad hoc proceedings, while the accompanying chorus of critique and counter-critique is populated with multiple actors and interests across the world. This chapter seeks to capture this distinct and fragmented universe. First, the authors map consent to arbitration, not on a generic per signed bilateral investment treaty basis, but rather by tracking multilateral, bilateral and unilateral consents in force. Second, they provide a description and overview of the over 1,100 registered cases up to January 2020, focusing inter alia on case outcomes, rules, cases types, institution, parties, economic sector and legal basis. Third, they trace discontent with regime, charting the origin of legitimacy crisis and its maturing over time. It ends by discussing both state-led efforts at reform and the extent to which arbitrators themselves have adjusted reflexively to the backlash.