The “established by law” criterion recently emerged as an independent element of Article 6 of the European Convention on Human Rights (ECHR), through the European Court of Human Rights’ (ECtHR’s) judgment in Ástráðsson v. Iceland. The criterion imposes the obligation on states to appoint judges in accordance with the respective legal framework. Its emergence occurred at a precarious moment in European intergovernmental politics, with illiberal governments in several European states exhibiting tactics aimed at softening obstacles to their governing powers, upheld by their respective judiciaries. Through a dialog between the European Free Trade Association (EFTA) Court, the Court of Justice of the European Union (CJEU), and the ECtHR, the “established by law” criterion has now emerged in the European constitutional repository for thwarting such tactics. In this article, the story of this development is told through highlights from the case law of the European supranational courts and through the Icelandic backstory of the Ástráðsson case. This story reveals important nuances in how the case law needs to be understood with regards to the constitutional forces at stake. The conceptual approach of the ECtHR in Ástráðsson is also analyzed in context with Lon Fuller’s rule of law principle of congruence, which provides a framework for evaluating the merits of the Court’s tactic.