The author seeks to illustrate the multiplicity of thoughts and varied techniques deployed in interpreting consent in investment arbitration. The chapter shows that the steady rise of varied international disputes has generated significant debate about the interpretation and application of the principle of consent. International courts and tribunals are being increasingly criticized by States for their jurisdictional overreach. The underlying problem, as the author sees it, may well be whether the contours of consent to arbitration are clear. Investment arbitration tribunals while dealing with the question of State consent have shown sharp divisions on the notion of consent. The varied approaches taken by arbitral tribunals to State consent highlights the indeterminacy of the contours of consent. The chapter finds support for its argument in a case study of the issue of State consent in the context of the interpretation of Most-Favoured Nation clauses.