This chapter reviews the basic principles of the mechanisms that govern the life of an award in investor-state dispute settlement (ISDS) after it was rendered, in particular annulment and set-aside. It analyses the similarities and differences between the two review procedures in terms of preserving the finality of an award as an essential feature of ISDS, while considering competing policy considerations. It first examines annulment according to Article 52 of the Convention on the Settlement of Investment Disputes between States and Nationals of Other States (ICSID Convention) and the performance of the ad hoc committees in their role as guardians of both the arbitral process and the finality of awards. It then briefly compares this ‘tailor-made’ review mechanism with the set-aside procedure for non-ICSID awards under domestic arbitration law at the seat of arbitration in domestic courts. Finally, the chapter reflects on the general increase in challenges to awards in recent years and the implications for ‘finality’ in ISDS.</p