This article conducts a critical assessment as to whether the current provisions on investor state dispute settlement (ISDS) under the Comprehensive and Progressive Agreement for Trans Pacific Partnership (CPTPP) reflect current best practice. It explores the CPTPP and its investor state dispute settlement (ISDS) provisions, and considers the underlying reasons for the suspension of particular provisions regarding ISDS. The ISDS provisions under the CPTPP will be compared to those under its predecessor, the Trans Pacific Partnership agreement, in exploring some of the key concerns raised with such provisions generally. As a corollary, the influence of other sources, such as the UNCITRAL Working Group III and the amendment of the ICSID Rules in reviewing ISDS will be evaluated. There will also be an assessment of the ISDS mechanisms in the CPTPP as compared with those in other investment treaties and trade agreements. Finally, a set of policy recommendations will be made on the basis of best practice in ISDS.