CETA, the EU-Vietnam FTA, and the EU-Singapore FTA are the first investment treaties to replace the practice of ad hoc tribunals and party-appointed arbitrators with a two-tiered investment tribunal system (ITS), consisting of a standing tribunal of first-instance and an appeal tribunal, comprised of a roster of members who are pre-selected by the treaty parties. Underlying this retreat to domestic court structures is the perception of partiality sometimes associated with party-appointed arbitrators. The article explores this risk of bias rationale and identifies potential drawbacks associated with the shift away from disputing party involvement in the selection of the tribunal, towards a more institutionalised form of adjudication. The array of foreseeable challenges with regard to the identity, tenure, and qualifications of arbitral members, particularly when combined with the duty to remain available and prohibition on ‘double-hatting’, cast doubt on the efficacy of these reforms in resolving the legitimacy concerns that spawned its creation. A better solution might be to expand the role of arbitral institutions in mediating the link between the parties and their chosen arbitrator.