Machine generated contents note: Part I. Why Do We Need a Theory of Legitimate Expectations?: 1. Introduction; 2. The formalist conception of legitimate expectations and different paradigms of the investment treaty regime: a critique; Part II. What is the Theory of Legitimate Expectations?: 3. Theoretical foundations for the use of moral philosophy of promise and conceptualisation of legitimate expectations; 4. The voluntarist conception of legitimate expectations and enforcement of sovereign promise; 5. 'Letting investors down', protection of trust, and assurance conception of legitimate expectations; 6. Protecting against investors' detrimental reliance: reliance conception of legitimate expectations; 7. In search of the most suitable conception of legitimate expectations; Part III. What is the Application of the Theory of Legitimate Expectations?: 8. Normative consequences of the reliance theory of legitimate expectations; 9. Rethinking remedies for a breach of legitimate expectations: corrective justice and reliance damages.