Investor–State Dispute Settlement (ISDS) faces a persistent legitimacy crisis driven by inconsistent arbitral interpretations of similar treaty provisions. While tribunals lack a formal doctrine of precedent, they rely on jurisprudence constante, engaging prior awards as persuasive authority to balance consistency with treaty-specific flexibility. Recent reform proposals advocating standing adjudicatory mechanisms, such as the EU–Chile Model, the CETA Tribunal, and the proposed Multilateral Investment Court, seek to address inconsistency through institutionalisation. This blog piece examines whether such mechanisms strengthen jurisprudence constante or risk hardening it into binding precedent. It argues that legitimacy depends on designing standing mechanisms that institutionalise reasoned engagement with prior decisions without undermining flexibility or state autonomy.