This book assesses stability guarantees through the lens of the legitimate expectations principle to offer a new perspective on the stability concept in international energy investments. The analysis of the interaction between the concepts of stability and legitimate expectations reveals that there are now more opportunities for energy investors to argue their cases before arbitral tribunals. The book offers detailed analyses of the latest energy investment arbitral awards from Spain, Italy and the Czech Republic, and reflects on the state of the art of the legitimate expectations debate and its relationship with the stability concept. The author argues that, in order to achieve stability, the legitimate expectations principle should be employed as the main investment protection tool when a dispute arises on account of unilateral host state alterations. This timely work will be useful to both scholars and practitioners who are interested in international energy law, investment treaty arbitration, and international investment law.