1. Introduction: The Legitimacy Crisis and the Empirical Turn, Daniel Behn, Ole Kristian Fauchald, Malcolm Langford; 2. The International Investment Regime and its Discontents Daniel Behn, Ole Kristian Fauchald, Malcolm Langford; Part I. Process Legitimacy: Independence and Impartiality. 3. Testing Cognitive Bias: Experimental Approaches and Investment Arbitration Sergio Puig, Anton Strezhnev; 4. The Influence of Law Firms in Investment Arbitration Runar Hilleren Lie; 5. Arbitrator Challenges in International Investment Tribunals Chiara Giorgetti; 6. Dissents in Investement Arbitration: On Collegiality and Individualism Daphna Kapeliuk; Part II. Process Legitimacy: Legal Reasoning. 7. Foreign Investors, Domestic Courts and Investment Treaty Arbitration Szilárd Gáspár-Szilágyi; 8. Ensuring Correctness or Promoting Consistency: Tracking Policy Priorities in Investment Arbitration through Large-scale Citation Analysis Wolfgang Alschner; 9. Fair and Equitible Treatment: Ordering Chaos through Precedent Florian Grisel, Meng Jia Yang; Part III. Output Legitimacy:10. The West and the Rest: Geographic Diversity and the Role of Arbitrator Nationality in Investment Arbitration Malcolm Langford, Daniel Behn, Maxim Usynin; 11. Mixing Methodologies in Empirically Investigating Investment Arbitration and Inbound Foreign Investment Shiro Armstrong, Luke Nottage; 12. Double Jeopardy? The Use of Investment Arbitration in Times of Crisis Cedric Dupont, Thomas Schultz, Merih Angin; 13. Who has Benefited Financially from Investment Treaty Arbitration? An Evaluation of the Size and Wealth of Claimants Gus Van Harten, Pavel Malysheuski; 14. Explaining China's Relative Absence from Investment Treaty Arbitration Fredrik Lindmark, Daniel Behn, Ole Kristian Fauchald; Part IV. Legitimation Strategies. 15. Does International Arbitration Enfeeble or Enhance Local Legal Institutions? Catherine Rogers, Christopher Drahozal; 16. Learning from Investment Treaty Law and Arbitration: Developing States and Power Inequalities Mavluda Sattorova, Oleksandra Vytiaganets; 17. Legitimation through Modification: Do States Seek More Regulatory Space in Their Investment Agreements? Tomer Broude, Yoram Haftel, Alex Thompson.