Key facts of the case:

Reference for a preliminary ruling — Citizenship of the Union — Article 21 TFEU — Freedom to move and reside in the Member States — Law of a Member State abolishing privileges and prohibiting the conferring of new noble titles — Surname of an adult, national of that State, obtained during a habitual residence in another Member State of which that person also holds the nationality — Name comprising tokens of nobility — Residence in the first Member State — Refusal by the authorities of the first Member State to enter the name acquired in the second Member State in the register of civil status — Justification — Public policy — Incompatibility with the essential principles of German law

Results (sanctions) and key consequences of the case:

...the Court (Second Chamber) rules as follows:

Article 21 TFEU must be interpreted as meaning that the authorities of a Member State are not bound to recognise the name of a citizen of that Member State when he also holds the nationality of another Member State in which he has acquired that name which he has chosen freely and which contains a number of tokens of nobility, which are not accepted by the law of the first Member State, provided that it is established, which it is for the referring court to ascertain, that a refusal of recognition is, in that context, justified on public policy grounds, in that it is appropriate and necessary to ensure compliance with the principle that all citizens of that Member State are equal before the law.