Since its Achmea judgment, the CJEU and investment arbitration are in open conflict. The EU's constitutional principle of autonomy collides with investor-state arbitration clauses contained in investment treaties concluded by EU member states. Due to the insecurity created by this conflict, the current system of investment protection within the EU, numerous investment treaties between EU Member States and third states as well as commercial arbitration are called into question. To overcome these issues, Jan Philipp Koster develops a contextual reading of the CJEU's jurisprudence and considers its consequences for arbitration proceedings. He concludes his book by discussing future mechanisms that may be established to protect investments within the European single market.