This case commentary examines the award rendered in Seda v. Colombia, the first investment arbitration award to address and apply a self-judging security exception clause. In line with the approach of the ICJ and WTO panels, the arbitral tribunal confirmed that the self-judging nature of the clause does not preclude its justiciability or the tribunal’s jurisdiction. Rather, it affects the standard of review to be applied by the tribunal, resulting in a broader interpretation of the clause’s conditions. However, the clause in question differs fundamentally from those previously analysed in international case law, as its footnote expressly limits the tribunal’s discretion to review it, thereby reinforcing the doctrine of non-justiciability. This yearbook chapter critically analyses the legal reasoning adopted by the tribunal concerning the implications of the self-judging character of the security exception. It argues that the tribunal’s reasoning fails to give effect to the normative value of the footnote and risks undermining the treaty text. It also assesses the legal effect of the exception as a merits defence, as considered by the tribunal, and its application based on good faith at that stage.