The Court of Justice of the European Union has been criticised increasingly for its approach to international law. While much literature focuses on reluctance to apply international law (ie refusing direct effect), this criticism also includes interpretation, arguably a more contentious area. The Court interprets international treaties through either the Vienna Convention or its own teleological method, with the latter increasingly applied. The legitimacy of applying localised methods of interpretation to international treaty law is debated in scholarship. Whether the Court’s case law applying international law is Völkerrechtsfreundlichkeit (friendliness to international law) is the focus of most contributions in this area. This Article seeks to move beyond that debate by demonstrating the Court should in all instances seek to achieve the legal imperatives of certainty and justice. It is explained that justice divides into ‘thin’ and ‘thick’ forms. Whilst ‘thin’ justice is widely accepted and amounts to treating like cases alike, substantive (‘thick’ justice) outcomes are inherently debatable. The Article proves the Court is failing to clearly distinguish cases (‘thin’ justice) and that case law is uncertain. There are also significant questions concerning ‘thick’ justice. The Court has been subject to criticism for substantive outcomes in this area, with the Commission and Council even seeking to limit its role. With case law that is uncertain and appears unjust it is argued that there is failure in this ‘integral part of EU law.’ The Court is now under increased pressure, and it is uncertain how it will respond. There are certainly cautionary lessons to be learned concerning the importance of paying proper attention to justice and certainty for EU law as a whole, and beyond.

CJEU case law has long emphasized the autonomy of the EU legal order, recently triggering the foreclosure of intra-EU investment arbitration. Though academic discourse has treated this as a European peculiarity, autonomy is not unfamiliar to international law as an inherent attribute of all international organizations (IOs). This Article traces how the CJEU employed this as the basis for the development of a legal principle of significant constitutional role in safeguarding the EU’s jurisdictional integrity. First, It considers the EU conception of autonomy on the basis of two identified dimensions of IOs’ autonomy under international law. Political autonomy characterizes the scope of an IO’s powers and its independent legal personality. Institutional autonomy denotes its (im)permeability to external norms. Second, the Article examines autonomy’s different normative status under international and EU law as a legal notion and a constitutional principle, respectively. Rather than viewing the latter as an EU invention, it amounts to a Pygmalian judicial creation—the CJEU drew inspiration from a notion of international law and adapted it within the Union framework. The Article justifies these adaptations by reference to international law in light of the EU’s institutional-judicial architecture and the intertwining of autonomy with, inter alia, Article 2 TEU values.