The legitimacy crisis of ISDS in Europe has prompted the EU – an emerging actor in international investment law – to reform this field. In particular, the EU reform was designed to enhance the rule of law in international investment law, as a means of legitimising the field. However, the reform of international investment law has ultimately exposed the clash of different visions of the rule of law in international law and the multifaceted nature of this concept. The purpose of this book was to evaluate the EU’s vision and its contribution to the development of international law in the field of investment. In particular, the book sought to assess whether the EU reform addresses the key international investment law problems and in doing so contributes to the achievement of the rule of law and legitimacy. To answer this question, a substantial analysis was undertaken of EU investment law and policy in both its internal dimension (Part II) and external relations (Part III), and placed in the broader context of international investment law and its reform (Part I). As many scholars have written about international investment law, what value does this book add? The following observations encapsulate the findings of this research and attest to its relevance and contribution to the international investment law reform debate.