Abstract
The principle of autonomy of EU law sits at the core of the current clash between EU law and
ISDS. Considering the widespread rejection by investment arbitration tribunals of the Court
of Justice’s Achmea case law, this chapter examines the nature, scope and content of the
principle of autonomy of EU law in the context of ISDS. It considers relevant case law of
both the Court of Justice and arbitral tribunals together with literature on the nature of the EU
legal order from an international law perspective and on the principle of autonomy. It also
examines the possibility to claim the autonomy of EU law as a norm of public policy and the
relevance of pursuing such an approach.