The principle of effective judicial protection (EJP) has traditionally been understood as a ‘procedural’ principle, used as a standard to assess national procedures applicable when individuals claim a right deriving from EU law. The EJP became part of EU primary law with Lisbon. This recognition has stimulated an evolution led by the CJEU. In several recent landmark decisions, the Court has made reference to the principle of EJP and operationalized it in quite different fields. The decisions of the Court and the changes in EU primary law are transforming EJP from a procedural into a more ‘substantive’ principle, of a constitutional nature. First, EJP is now a fundamental right under Art. 47 Charter. Second, EJP operates as a more structural principle, closely connected to the rule of law. Here the relevant provision is Art. 19(1) TEU. This paper aims to map the on-going evolution of the principle of EJP and to reflect on how recent Court’s decisions are transforming its nature.