Although it is true that the organisation of justice in the EU Member States falls within the competence of those Member States, in the exercise of that competence they are required to comply with their obligations deriving from EU law. Based on the criteria of judicial independence, the case-law of the CJEU has broadened the scope of protection of the principle of the Union of law (what does it protect? what does it prohibit?). Such developments began with the “Portuguese Judges” judgment (C-64/16, ECLI:EU:C:2018:117), in which the CJEU was asked to determine whether there is a general principle of EU law according to which the authorities of the Member States are obliged to respect the independence of national judges as functionally European judges. This text recalls the circumstances of this case-law to understand the subsequent CJEU steps on judicial independence, so that Article 19 TEU gives tangible expression to the value of the rule of law asserted in Article 2 TEU.