The Investor‐State Dispute Settlement System has been subject to increasing criticism. Questions about finality of the award, consistency, correctness, and predictability of the arbitration system have been raised. The public component of this international arbitration proceeding, the substantial amounts of money at stake and the potential impact of the awards on State’s regulatory powers, have been a matter of controversy. The standard of review of the awards and the establishment of a permanent appeal panel versus ad‐hoc arbitrators is an on‐ongoing debate. This article aims at analysing practice, procedure and some investment treaties which include an appeal mechanism in order to establish if its inclusion is required.