The Court of Justice of the European Union characterizes the Union as a Rechtsunion: a law-governed union. The conception of “the law” in Article 19 paragraph 1 of the Treaty on European Union transcends the Treaties, according to the Vice-President of the Court of Justice, Koen Lenaerts. This thesis demonstrates with reference to the work of Georg Jellinek that the Union is a non-sovereign state and, with reference to the work of Eugen Ehrlich in particular, that the state-based perception of law is a misperception. Not all production of law is reserved to the state and not all law is state-recognized law. There is extra-state law. It has been alleged that the Court of Justice of the European Union has had “a free law attitude”. The author discusses the free law doctrine developed at the beginning of the twentieth century and has made literal translations of writings in German, French and Italian by the main representatives of the free law movement. The free law doctrine provides a descriptive framework for the case-law of courts. The author describes the creation by the Court of Justice of four constitutional principles of Union law through its case-law. He concludes that every court is, to quote Hermann Kantorowicz, praeter legem law-creatively active and has, in that sense, a free law attitude. The decisions of judges are often volitional decisions. How the law will be applied should be predictable but volitional decisions, because they are unpredictable, are inconsistent with the principle of legal certainty. In the Union and its member states the judiciary and not the statute or “the law” is pre-eminent. The author suggests how the concept of law should be defined in a material Rechtsunion. He argues that societal legal norms could be provided with an appropriate position consistent with the principle of legal certainty by making the validity of a societal legal norm contingent on its material lawfulness.