The idea of establishing an appeal mechanism for Investor-State Dispute Resolution (ISDS) awards is not novel. Currently, the United Nations Commission on International Trade Law Working Group III (WG III) is discussing potential reform of the ISDS system, including an appeal mechanism and a Multilateral Investment Court (MIC) system. This article does not argue whether the ISDS reform is necessary. Instead, it will use WG III’s finding that the ISDS reform is necessary as a starting point to analyse the establishment of a MIC system. The article will briefly review commonly raised reasons for the ISDS reform and the European Union’s (EU’s) proposal to create the MIC system. It will then analyse the structure of the appellate mechanism – a stand-alone appellate body – especially focusing on the challenge of arbitrators and the enforcement of appellate awards. The article considers whether, if the MIC system is adopted, to create a single MIC system or a multiple MICs system. Finally, it notes that there are issues that need further consideration on creating the MIC system, specifically the scope of review and the double hatting issue.