The Swiss Federal Supreme Court has rendered over twenty-five decisions in setting-aside proceedings brought against treaty-based arbitral awards to date. Against the backdrop of conflicting decisions by arbitral tribunals on many issues that regularly arise in investment arbitrations, the emergence of a consistent body of jurisprudence by the Court may be of interest even outside of Switzerland. The present contribution provides an overview of the procedure for setting aside arbitral awards before the Court and assesses the relevance of the various grounds for setting-aside that can be invoked specifically with regard to treaty-based arbitral awards. It addresses the Court’s most interesting findings in relation to the fundamental requirements for obtaining protection under investment treaties and shows that the Court will likely further contribute to the debate on jurisdictional issues in treaty-based arbitrations.