CURIA - Documents 9 of 11 https://curia.europa.eu/juris/document/document_print.jsf?docid=753... 41 Nevertheless, the fact that a matter falls within the competence of the Member States does not alter the fact that, in situations covered by European Union law, the national rules concerned must have due regard to the latter (see, to that effect, Case C‑274/96 Bickel and Franz [1998] ECR I‑7637, paragraph 17 (as regards national provisions in the sphere of criminal legislation and the rules of criminal procedure); Case C‑148/02 Garcia Avello [2003] ECR I‑11613, paragraph 25 (as regards national rules governing a person’s name); Case C‑403/03 Schempp [2005] ECR I‑6421, paragraph 19 (as regards national rules relating to direct taxation); Case C‑145/04 Spain v United Kingdom [2006] ECR I‑7917, paragraph 78 (as regards national rules determining the persons entitled to vote and to stand as candidates in elections to the European Parliament)). 42 It is clear that the situation of a citizen of the Union who, like the applicant in the main proceedings, is faced with a decision withdrawing his naturalisation, adopted by the authorities of one Member State, and placing him, after he has lost the nationality of another Member State that he originally possessed, in a position capable of causing him to lose the status conferred by Article 17 EC and the rights attaching thereto falls, by reason of its nature and its consequences, within the ambit of European Union law. 43 As the Court has several times stated, citizenship of the Union is intended to be the fundamental status of nationals of the Member States (Case C‑184/99 Grzelczyk [2001] ECR I‑6193, paragraph 31; Case C‑413/99 Baumbast and R [2002] ECR I‑7091, paragraph 82). 44 Article 17(2) EC attaches to that status the rights and duties laid down by the Treaty, including the right to rely on Article 12 EC in all situations falling within the scope ratione materiae of Union law (see Case C‑85/96 Martínez Sala [1998] ECR I‑2691, paragraph 62, and Schempp, paragraph 17). 45 Thus, the Member States must, when exercising their powers in the sphere of nationality, have due regard to European Union law (Micheletti and Others, paragraph 10; Mesbah, paragraph 29; Case C‑192/99 Kaur [2001] ECR I‑1237, paragraph 19; and Zhu and Chen, paragraph 37). 46 In those circumstances, it is for the Court to rule on the questions referred by the national court which concern the conditions in which a citizen of the Union may, because he loses his nationality, lose his status of citizen of the Union and thereby be deprived of the rights attaching to that status. 47 In this regard, the national court essentially raises the question of the proviso formulated in the Court’s case-law cited in paragraph 45 above, to the effect that the Member States must, when exercising their powers in the sphere of nationality, have due regard to European Union law, and also the question of the consequences of that proviso in a situation such as that in the case in the main proceedings. 48 The proviso that due regard must be had to European Union law does not compromise the principle of international law previously recognised by the Court, and mentioned in paragraph 39 above, that the Member States have the power to lay down the conditions for the acquisition and loss of nationality, but rather enshrines the principle that, in respect of citizens of the Union, the exercise of that power, in so far as it affects the rights conferred and protected by the legal order of the Union, as is in particular the case of a decision withdrawing naturalisation such as that at issue in the main proceedings, is amenable to judicial review carried out in the light of European Union law. 49 Unlike the applicant in the case giving rise to the judgment in Kaur who, not meeting the definition of a national of the United Kingdom of Great Britain and Northern Ireland, could not be deprived of the rights deriving from the status of citizen of the Union, Dr Rottmann has unquestionably held Austrian and then German nationality and has, in consequence, enjoyed that status and the rights attaching thereto. 50 Nevertheless, as several of the governments having submitted observations to the Court have argued, if a decision withdrawing naturalisation such as that at issue in the main proceedings is based on the deception practised by the person concerned in connection with the procedure for 26/05/2021, 10:03