OPINION OF ADVOCATE GENERAL

MENGOZZI

delivered on 12 July 2018 (1)

Case C‑221/17

M.G. Tjebbes,

G.J.M. Koopman,

E. Saleh Abady,

L. Duboux

v

Minister van Buitenlandse Zaken

(Request for a preliminary ruling
from the Raad van State (Council of State, Netherlands))

(Reference for a preliminary ruling — Citizenship of the Union — Article 20 TFEU — Articles 7 and 24 of the Charter of Fundamental Rights of the European Union — Nationality of a Member State and of a third country — Loss of the nationality of a Member State as a result of living outside the European Union for an uninterrupted period of 10 years — Unity of nationality within the family — Best interests of the child)

I.      Introduction

1.        This request for a preliminary ruling from the Raad van State (Council of State, Netherlands) concerns the interpretation of Articles 20 and 21 TFEU and Article 7 of the Charter of Fundamental Rights of the European Union (‘the Charter’).

2.        In essence, the referring court is uncertain what discretion Member States have in laying down the conditions for loss of nationality. The Court previously considered this issue in the judgment of 2 March 2010, Rottmann (C‑135/08, EU:C:2010:104), albeit in a different legal and factual context.

3.        In the present case it is, in essence, a question of whether Article 20 TFEU precludes provisions of national law under which an adult national of a Member State, who also has another nationality, loses the nationality of that State on the grounds that he has resided for more than 10 years, without interruption, in the territory of a third country. The question also arises as to whether citizenship of the Union and the child’s best interests preclude a Member State from providing that a child of that person loses the nationality of that Member State at the same time.

4.        As I shall explain in this Opinion, I consider that only the second question should be answered in the affirmative. As regards the first question, I consider that there is no need to depart from the grounds chosen by the national legislature for loss of citizenship of the Union in order to examine whether such legislation complies, inter alia, with the principle of proportionality. In particular, observance of that principle does not, in my view, involve an examination of either the indirect consequences entailed by the application of that legislation for the situation of each of the persons concerned or the circumstances specific to each individual case which are unrelated to the connecting factor between that person and the Member State concerned as chosen by the national legislature. As the Greek Government contended at the hearing before the Court, I consider that that solution is the only one which makes it possible to ensure that the competence of Member States to lay down the conditions for acquisition and loss of nationality is respected, and to conform to the scope of review of the proportionality of a national measure entailing loss of citizenship of the Union in the light of EU law.

II.    Facts, legal background and the question referred

5.        The question for the Court to consider was referred for a preliminary ruling in proceedings between Ms M.G. Tjebbes, Ms G.J.M. Koopman, Ms E. Saleh Abady and Ms L. Duboux, on the one hand, and the Minister van Buitenlandse Zaken (Minister for Foreign Affairs, Netherlands) (‘the Minister’), on the other hand, concerning the latter’s decision not to examine their applications for renewal of their national passports on the ground that those persons, whilst retaining the nationality of the third countries in which they each reside, had lost Netherlands nationality by operation of the provisions of the Rijkswet op het Nederlanderschap (the Law on Netherlands nationality).

6.        The account of the legal background given by the referring court states that under Article 15(1)(c) of the Law on Netherlands nationality an adult loses his Netherlands nationality if he also holds a foreign nationality and if, after attaining his majority and while holding both nationalities, he has his principal residence for an uninterrupted period of 10 years outside the Netherlands and outside the territories to which the EU Treaty applies. Under Article 16(1)(d) of the same law, a minor loses his Netherlands nationality if his father or mother loses his or her Netherlands nationality pursuant, inter alia, to Article 15(1)(c) of that law.

7.        According to Article IV of the Rijkswet van 21 december 2000 tot wijziging Rijkswet op het Nederlanderschap (verkrijging, verlening en verlies van het Nederlanderschap) (Law of 21 December 2000 amending the Law on Netherlands nationality (acquisition, granting and loss of Netherlands nationality)), the 10-year period referred to in Article 15(1)(c) of the Law on Netherlands nationality cannot commence earlier than 1 April 2003.

8.        The explanations provided by the referring court also make clear that, under Article 15(3) of the Law on Netherlands nationality, the period laid down in Article 15(1) of that law is interrupted if the person concerned, for a period of no less than one year, has his principal residence in the Netherlands or in the territories to which the EU Treaty applies. Moreover, under Article 15(4) of that law, the period will be interrupted if the person concerned applies for a declaration regarding the possession of Netherlands nationality or a travel document (passport) or a Netherlands identity card within the meaning of the Paspoortwet (Law on Passports). A new 10-year period starts to run as from the date of issue of one of those documents.

9.        Article 6(1)(f) of the Law on Netherlands nationality allows adult foreign nationals who have lost Netherlands nationality, for the purposes of Article 15(1)(c) of the Law on Netherlands nationality, to recover that nationality by becoming established for no less than one year in the Netherlands or in another country within the Kingdom of the Netherlands, (2) provided they hold a permit of indefinite duration.

10.      Furthermore, the referring court notes, in essence, that the Law on Netherlands nationality was adopted in the context of the international obligations to which the Kingdom of the Netherlands is committed. Thus, Article 7(3) of the Convention on the Reduction of Statelessness, which was concluded in New York on 30 August 1961 and entered into force on 13 December 1975 (‘the Convention on the Reduction of Statelessness’),(3) provides that, subject to the provisions, inter alia, of paragraph 4 of that article, a national of a Contracting State is not to lose his nationality, so as to become stateless, on the ground of departure or residence abroad. Article 7(4) of the convention states that a naturalised person may lose his nationality on account of residence abroad for a period of not less than seven consecutive years. In addition, Article 7(1)(e) of the European Convention on Nationality, signed at Strasbourg on 6 November 1997 and adopted within the framework of the Council of Europe, which entered into force on 1 March 2000 (4) (‘the European Convention on Nationality’), states that nationality may be lost ^{ex lege} in the absence of a genuine link between the State Party and a national residing abroad. Moreover, Article 7(2) of the convention states that a State Party may provide for the loss of its nationality by children whose parents lose that nationality unless one of the parents retains it.

11.      It is clear from the facts of the cases in the main proceedings that until 31 March 2013 Ms Tjebbes held Netherlands and Canadian nationalities by descent, Ms Koopman had held Netherlands nationality since birth and had acquired Swiss nationality by marriage, and Ms Saleh Abady held Iranian nationality and had acquired Netherlands nationality by naturalisation. On 1 April 2013, Ms Tjebbes had been residing in Canada, Ms Koopman in Switzerland, and Ms Saleh Abady in Iran for more than 10 years. They were all adults at that date.

12.      When he received applications for renewal of their respective passports, the Minister refused to examine those applications on the ground that those three persons had lost their Netherlands nationality pursuant to Article 15(1)(c) of the Law on Netherlands nationality. He noted that they had all had their principal residence outside the Netherlands, or outside the territories to which the EU Treaty applies, for an uninterrupted period of no less than 10 years. The Minister noted that each of them held another nationality and that during the course of that period no Netherlands travel document, Netherlands identity card or declaration regarding possession of Netherlands nationality had been issued to them.

13.      As regards Ms Duboux, Ms Koopman’s daughter, who on 1 April 2013 was a minor with both Netherlands and Swiss nationalities, the Minister rejected her passport application also, on the ground that at that date, since her mother had lost her Netherlands nationality, she herself had been deprived of her Netherlands nationality pursuant to Article 16(1)(d) of that law.

14.      The applicants in the main proceedings brought four separate actions before the rechtbank Den Haag (District Court, The Hague, Netherlands) against the Minister’s decisions. By separate rulings, the rechtbank Den Haag (District Court, The Hague) declared the actions brought by Ms Tjebbes, Ms Koopman and Ms Saleh Abady to be unfounded, although it declared the action brought by Ms Duboux to be well founded, and annulled the Minister’s decision relating to her whilst maintaining the legal effects of that decision. Consequently, the applicants in the main proceedings each lodged separate appeals against those rulings before the Raad van State (Council of State).

15.      The referring court states that the question before it is whether the loss of Netherlands nationality by operation of law is compatible with EU law, in particular with Articles 20 and 21 TFEU, read in the light of the judgment of 2 March 2010, Rottmann (C‑135/08, EU:C:2010:104). It takes the view that those articles are applicable, irrespective of whether the loss of citizenship of the Union is due to the loss, by operation of law, of the nationality of a Member State of the Union or to an individual decision, as was the case in Rottmann (C‑135/08, EU:C:2010:104).

16.      However, for the referring court, the way in which proportionality must be examined in situations like those at issue in the main proceedings cannot be inferred from Rottmann (C‑135/08, EU:C:2010:104). In that regard, the question arises as to whether conformity with the principle of proportionality of national rules that cause nationality to expire by operation of law can be examined in a general way or whether that principle necessarily means that each individual case must be taken into account.

17.      As regards the situation of adults, the referring court is of the opinion that there are convincing arguments for accepting that Article 15(1)(c) of the Law on Netherlands nationality is consistent with the principle of proportionality and, accordingly, compatible with Articles 20 and 21 TFEU. First of all, it is clear from the legislative history of Article 15(1)(c) of the Law on Netherlands nationality that the objective of the national legislature was to contribute to ‘international rules’ designed to eliminate or reduce statelessness and multiple nationality and that it is consistent with Article 7 of the European Convention on Nationality.

18.      The referring court notes that Article 15(1)(c) of the Law on Netherlands nationality provides for a period of 10 years before Netherlands nationality is lost, that period giving grounds for assuming that the persons concerned will have no, or only a very weak, link with the Netherlands and, accordingly, with the European Union. Furthermore, in its opinion, it is relatively simple to retain Netherlands nationality, because the 10-year period is interrupted if, during the course of that period, the person concerned resides for no less than one year without interruption in the Netherlands or the European Union, or obtains a declaration regarding possession of Netherlands nationality or a Netherlands identity card or travel document within the meaning of the Law on Passports. In addition, according to the referring court, anyone who qualifies for an ‘option’ for the purposes of Article 6 of the Law on Netherlands nationality is entitled to recover their Netherlands nationality.

19.      Lastly, although Article 7 of the Charter, concerning private and family life, may be relied on, the referring court considers that the Netherlands legislature does not appear to have acted arbitrarily in adopting Article 15(1)(c) of the Law on Netherlands nationality. However, in the view of the referring court, since it cannot be ruled out that the examination of compliance with the principle of proportionality may require each individual case to be examined, it is not clear whether or not a general statutory scheme such as the Law on Netherlands nationality is consistent with Articles 20 and 21 TFEU.

20.      As regards the situation of minors, the referring court states that Article 16(1)(d) of the Law on Netherlands nationality reflects the view of the national legislature that unity of nationality within the family is important. In the light of the judgment in Rottmann (C‑135/08, EU:C:2010:104), the referring court cannot assess whether that factor may be a reason to deprive a person of his nationality by operation of law. Moreover, it asks whether it is proportionate to deprive a minor of citizenship of the Union and the rights attaching purely for the sake of preserving unity of nationality within the family. Lastly, the referring court notes that a minor has little influence on the retention of his Netherlands nationality and that the possibilities for interrupting those periods of time or obtaining, for instance, a declaration regarding the possession of Netherlands nationality are not grounds for exception in the case of minors. Consequently, it is not clearly established whether or not Article 16(1)(d) of the Law on Netherlands Nationality is consistent with the principle of proportionality.

21.      The Raad van State (Council of State) therefore decided to stay the proceedings and to refer the following question to the Court for a preliminary ruling:

‘Must Articles 20 and 21 TFU, in the light of, inter alia, Article 7 of the [Charter], be interpreted — in view of the absence of an individual assessment, based on the principle of proportionality, with regard to the consequences of the loss of nationality for the situation of the person concerned from the point of view of EU law — as precluding legislation such as that in issue in the main proceedings, which provides:

(1)      that an adult, who is also a national of a third country, loses, by operation of law, the nationality of his or her Member State, and consequently loses citizenship of the Union, on the ground that, for an uninterrupted period of 10 years, that person had his or her principal residence abroad and outside the European Union, although there are possibilities for interrupting that 10-year period;

(2)      that under certain circumstances a minor loses, by operation of law, the nationality of his or her Member State, and consequently loses citizenship of the Union, as a consequence of the loss of the nationality of his or her parent, as referred to under (1) above?’

22.      That question was the subject of written observations from the applicants in the main proceedings, the Netherlands and Greek Governments, Ireland, and the European Commission. Ms Tjebbes, the Netherlands and Greek Governments and the Commission also submitted oral arguments at the hearing on 24 April 2018, at which the other interested parties were not represented.

III. Analysis

23.      Before considering the question raised with regard to the compatibility with Article 20 TFEU of the loss of nationality by adult Netherlands nationals (Section B) and Netherlands nationals who are minors (Section C), whilst taking into account the guidance provided by the Court in Rottmann (C‑135/08, EU:C:2010:104), I find it necessary, in the first place, even though this point has not been challenged by any of the parties concerned, to determine whether EU law is applicable and whether the Court has jurisdiction to answer the question referred for a preliminary ruling (Section A). Lastly, I shall consider briefly the request put forward at the hearing by the Netherlands Government that the Court should limit the temporal effects of the judgment to be delivered in the event that it were to find the relevant provisions of the Law on Netherlands nationality to be incompatible with Article 20 TFEU (Section D).

A.      The applicability of EU law and the jurisdiction of the Court to answer the question referred for a preliminary ruling

24.      As I mentioned above, the applicability of EU law has not been challenged by any of the parties concerned. Some doubts might nonetheless be expressed in that regard. First, it should be noted that the decisions contested in the main proceedings concerned not the withdrawal of Netherlands nationality and, consequently, the withdrawal of citizenship of the Union from the applicants in the main proceedings, but rather the decision not to issue Netherlands passports on the ground that those persons no longer have the nationality of the Kingdom of the Netherlands. Secondly, it is clear from the account of the facts provided by the referring court that the applicants in the main proceedings all reside in third countries and have not, in all likelihood, made use of their freedom of movement within the European Union.

25.      Such doubts can however be dismissed in my view.

26.      As regards the first point, it might be considered that the main proceedings have no connection with EU law since the referring court has to rule only on the lawfulness of the Minister’s decision not to issue passports applied for by third-country nationals who have already lost their Netherlands nationality and have therefore been deprived of citizenship of the Union.

27.      However, it is clear from the order for reference that to follow that line of reasoning, which seems to be the one adopted also by the Minister, would have the effect, under national law, of depriving the applicants in the main proceedings of any effective judicial remedy in respect of the Minister’s finding that they no longer held Netherlands nationality at the time the applications for renewal of their passports were submitted. It would appear that no other decision regarding the withdrawal of that nationality from them was adopted by the competent Netherlands authorities. That is why, according to the referring court, which, I would point out, is a court of last instance, it had been called upon to determine whether the Minister was right to base his decision not to issue the passports applied for on the premiss that the applicants in the main proceedings had all lost their Netherlands nationality (and therefore citizenship of the Union) by the time he was required to take his decision, and whether that decision, based on Articles 15(1)(c) and 16(1)(d) of the Law on Netherlands nationality, was consistent with EU law, in particular with the principle of proportionality set out in Rottmann (C‑135/08, EU:C:2010:104).

28.      Consequently, it is clear from the view taken by the referring court that the applicants in the main proceedings have not definitively lost their citizenship of the Union conferred by Article 20 TFEU, but are placed in a position capable of causing them to lose that status.

29.      According to Rottmann (C‑135/08, EU:C:2010:104, paragraph 42), such a situation falls, by reason of its nature and its consequences, within the ambit of EU law.

30.      As regards the second point, the fact that it would appear that the applicants in the main proceedings all reside in third countries and have not exercised their right to move freely within the European Union does not seem to me to entail a different consequence.

31.      Article 20(1) TFEU confers citizenship of the Union on every person holding the nationality of a Member State. The Court has made clear on several occasions that citizenship of the Union is intended to be the fundamental status of nationals of the Member States. (5)

32.      The Court has interpreted that provision in contexts in which the only connection with EU law was citizenship of the Union.

33.      Thus, in the judgment of 2 October 2003, Garcia Avello (C‑148/02, EU:C:2003:539, paragraphs 13 and 27), the Court accepted that the situation of children having the nationality of two Member States, who were born in the territory of one of those States and were lawfully resident there and who had never exercised their right to move freely, had a connection with EU law.

34.      Similarly, in Rottmann (C‑135/08, EU:C:2010:104), the Court, in contrast to the approach taken by the Advocate General, (6) did not look for a connection between the withdrawal of Mr Janko Rottmann’s naturalisation and his exercise of the right to move freely within the European Union. In paragraph 42 of the judgment in Rottmann (C‑135/08, EU:C:2010:104) the Court found that such a connection with EU law did exist on the ground that ‘the situation of a citizen of the Union who, like [Mr Rottmann], 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 [now Article 20 TFEU] and the rights attaching thereto falls, by reason of its nature and its consequences, within the ambit of EU law.’

35.      In addition, it should be noted that, since the judgment of 8 March 2011, Ruiz Zambrano (C‑34/09, EU:C:2011:124, paragraph 42), the Court accepts that there is a connection with EU law and that Article 20 TFEU applies to the situation of nationals of a Member State who have not exercised their right to move freely and who, as a result of a decision by that Member State, are deprived of the genuine enjoyment of the substance of the rights attaching to the status of citizen of the Union.

36.      In the present case, in contrast to the cases cited above, the applicants in the main proceedings all are already resident in third countries.

37.      However, that circumstance does not appear to me to mean that the situations in the main proceedings should not fall within the ambit of EU law.

38.      Indeed, the status of citizen of the Union is not reserved for nationals of Members States who reside or are present in the territory of the European Union. In providing that every citizen of the Union will enjoy the diplomatic and consular protection of any Member State in the territory of a third country in which the Member State of which they are nationals is not represented, Article 20(2)(c) TFEU in my view affirms this in unambiguous terms.

39.      However, Articles 15(1)(c) and 16(1)(d) of the Law on Netherlands nationality deprive Netherlands nationals who reside in a third country and fulfil the other conditions laid down in those articles, of the very status of citizen of the Union and, consequently, of even potential genuine enjoyment of all the rights attaching to that status.

40.      It would also, in my view, be a paradox if the Court were to deny the applicability of EU law in the main proceedings, where the situation under consideration is the only one in which residence outside the territory of the Netherlands entails the loss of citizenship of the Union. In the first place, the Law on Netherlands nationality does not apply to Netherlands nationals holding another nationality who reside, even for more than 10 years, in the territory of a Member State of the European Union. In the second place, as was confirmed by the Netherlands Government at the hearing, although Articles 15(1)(c) and 16(1)(d) of the Law on Netherlands nationality do apply to Netherlands nationals who are also nationals of another Member State and who reside for an uninterrupted period of more than 10 years in the territory of a third country, the consequences of the loss of Netherlands nationality are not comparable since those nationals remain, in principle, citizens of the Union because they retain the nationality of the other Member State. (7)

41.      It is in the light of those considerations that I take the view that EU law is applicable to the situations in the main proceedings, bearing in mind the fact that it is for each Member State, having due regard to EU law, to lay down the conditions for acquisition and loss of nationality. (8)

42.      In that regard, I would add that the answer to the question from the referring court should be structured solely around Article 20 TFEU and not by reference also to the interpretation of Article 21 TFEU. In so far as the main proceedings relate specifically to loss of citizenship of the Union and the applicants in the main proceedings have not exercised their rights relating to freedom of movement within the European Union, interpretation of Article 21 TFEU does not appear to me to be directly relevant, and would not, moreover, entail a different answer from that which would follow from interpretation of Article 20 TFEU alone. That approach, it seems to me, can also be inferred from the judgments of 30 June 2016, NA (C‑115/15, EU:C:2016:487), of 13 September 2016, Rendón Marín (C‑165/14, EU:C:2016:675), and of 10 May 2017, Chavez-Vilchez and Others (C‑133/15, EU:C:2017:354, paragraphs 49 and 57), in which the Court answered questions referred to it in the light of Article 20 TFEU, since the situations at issue, which involved citizens of the Union, did not fall within the ambit of Article 21 TFEU. (9)

43.      To conclude on this point, the applicability of Article 20 TFEU and therefore of EU law in the main proceedings necessarily means that the fundamental rights conferred by the Charter may be relied on by the applicants in the main proceedings, namely the right, mentioned by the referring court, to respect for private and family life, conferred by Article 7 of the Charter, and, in the case of Ms Duboux, the rights of the child under Article 24 of the Charter. As I have shown in earlier Opinions, the fundamental rights recognised by the Charter, which any authority of the Member States must respect when acting within the framework of EU law, are guaranteed to the addressees of the acts adopted by such an authority irrespective of any territorial criterion. (10)

44.      Consequently, as the Court made clear in Rottmann (C‑135/08, EU:C:2010:104, paragraph 46), I consider that the Court must answer the question from the referring court, which concerns the conditions in which citizens of the Union may, because they lose the nationality of a Member State, lose their citizenship of the Union and thereby be deprived of the rights attaching thereto.

45.      I now come to the first part of the question from the referring court concerning the loss of nationality by adult Netherlands nationals.

B.      Compatibility with Article 20 TFEU, and Article 7 of the Charter, of the loss of nationality by adult Netherlands nationals provided for in Article 15(1)(c) of the Law on Netherlands nationality

46.      In the first part of the question it referred for a preliminary ruling, the referring court asks, in essence, whether Article 20 TFEU, in the light of the judgment of 2 March 2010, Rottmann (C‑135/08, EU:C:2010:104), must be interpreted as precluding Article 15(1)(c) of the Law on Netherlands nationality in so far as adults are concerned.

47.      In Rottmann (C‑135/08, EU:C:2010:104) the Court laid down, inter alia, the principle that a decision withdrawing the naturalisation of a national of a Member State was amenable to judicial review carried out in the light of EU law.

48.      Initially, in paragraphs 50 to 54 of the judgment in Rottmann (C‑135/08, EU:C:2010:104), the Court determined, in essence, whether the decision withdrawing naturalisation pursued an objective that was worthy of protection, in that case, the deprivation of nationality because of deception by the person concerned at the time nationality was acquired. In that regard, the Court held that it was legitimate for a Member State to wish to protect the special relationship of solidarity and good faith between it and its nationals and also the reciprocity of rights and duties, which form the bedrock of the bond of nationality. The Court supported that conclusion relating to the legitimacy of such a measure on the basis of the general principle of international law that no one is arbitrarily to be deprived of his nationality, as well as the relevant provisions of the Convention on the Reduction of Statelessness and on those of the European Convention on Nationality. It held, in paragraph 54 of that judgment, that that conclusion remained, in theory, valid when the consequence of withdrawal of the nationality of the Member State concerned is the loss of citizenship of the Union.

49.      Secondly, and this is what gave rise to uncertainties from the referring court, the Court added a limitation to that theoretical conclusion, namely that the decision withdrawing naturalisation at issue in Rottmann (C‑135/08, EU:C:2010:104) should observe the principle of proportionality ‘so far as concerns the consequences it entails for the situation of the person concerned in the light of EU law’ (11)or taking ‘into account the ^consequences that the decision entails for the person concerned and, if relevant, for the members of his family with regard to the loss of the rights enjoyed by every citizen of the Union’. (12)

50.      Although, as I shall explain below, the scope of the review carried out in paragraphs 55 to 58 of the judgment in Rottmann (C‑135/08, EU:C:2010:104) is difficult to assess, I consider nonetheless that, according to the Court’s reasoning in that judgment, in order to determine whether withdrawal of nationality by a Member State, entailing loss of citizenship of the Union for the person concerned, is consistent with Article 20 TFEU, it is necessary first to examine the public-interest nature of the objective behind that measure and secondly to determine whether the principle of proportionality has been observed.

1.      The public-interest objective pursued by Article 15(1)(c) of the Law on Netherlands nationality

51.      In order for the loss of nationality provided for in Article 15(1)(c) of the Law on Netherlands nationality to be consistent with EU law, it must pursue a public-interest objective, which means that the loss must be appropriate for attaining the objective pursued and that the deprivation stemming from that article cannot be considered to be an arbitrary act. (13)

52.      Article 15(1)(c) of the Law on Netherlands nationality provides that any Netherlands national who also holds the nationality of another State and who has resided for a period of no less than 10 years, without interruption, outside the Netherlands and outside the territories to which the EU Treaty applies loses his Netherlands nationality by operation of law.

53.      In that regard, I am entirely in agreement, first of all, with the Netherlands Government’s position that, in essence, when exercising its competence to lay down the conditions for acquisition and loss of nationality, a Member State is entitled to start from the premiss that nationality is the expression of a genuine link between it and its nationals.

54.      Next, I consider that it is not unreasonable for a national legislature to choose, from among the various factors that may reflect the loss of such a genuine link, the habitual residence of its nationals in the territory of a third country for a sufficiently long period.

55.      In that regard, it should be noted that such a choice is accepted at international level. Article 7(4) of the Convention on the Reduction of Statelessness provides for loss of nationality on account of a person’s residence abroad for a long period, provided such loss does not render him stateless. Similarly, Article 7(1)(e) of the European Convention on Nationality provides that nationality may be lost ex lege where there is a lack of a genuine link between the State and a national residing abroad. The Explanatory Report to that convention states that that provision seeks to allow a State, which so wishes, to prevent its nationals who have lived abroad for a long time from retaining the nationality of that State where a link with the latter no longer exists or has been replaced by a link with another country, on the understanding that, as in the present case, these are persons with dual nationality and there is therefore no risk of statelessness. (14)

56.      In addition, Article 15(1)(c) of the Law on Netherlands nationality is based solely on a criterion for removal from the territory of the European Union, regardless of the other nationality held by Netherlands nationals. As the Netherlands Government confirmed at the hearing, both Netherlands nationals having the dual nationality of a third country and those having the dual nationality of another Member State are covered by the loss by operation of law provided for in Article 15(1)(c) of the Law on Netherlands nationality, when they meet the criterion of uninterrupted residence in the territory of a third country for a period of 10 years.

57.      Lastly, as the referring court pointed out, there is nothing in the case file to show that deprivation of nationality under Article 15(1)(c) of the Law on Netherlands nationality constitutes an arbitrary act.

58.      Without, at this stage of the reasoning, going into more detailed consideration of the proportionality of depriving a dual-nationality Netherlands national of that nationality on the grounds that he has resided in a third country for a period of more than 10 years, that period does not appear to be excessively short. None of the parties concerned has challenged the length of this period. Moreover, irrespective of the shortage of prior information which the applicants in the main proceedings complained of with regard to that legislation, it should be noted that the law amending the Law on Netherlands nationality was adopted in 2000 and did not enter into force until three years later. Accordingly, I consider that it was sufficiently foreseeable. Moreover, the present proceedings satisfactorily show that the deprivation of nationality provided for by Article 15(1)(c) of the Law on Netherlands nationality is subject to judicial review.

59.      Consequently, I consider that the deprivation of nationality provided for in Article 15(1)(c) of the Law on Netherlands nationality pursues a legitimate objective.

2.      The proportionality of Article 15(1)(c) of the Law on Netherlands nationality

60.      It is apparent from the request for a preliminary ruling that the referring court is uncertain, in essence, whether it is allowed simply to determine whether the conditions for the application of Article 15(1)(c) of the Law on Netherlands nationality are met or whether, according to the principle of proportionality as interpreted by the Court in Rottmann (C‑135/08, EU:C:2010:104, paragraphs 55 to 58), it is also required to take into consideration the individual circumstances in each case that are capable of demonstrating that a genuine link has been maintained with the Member State concerned, as claimed by the applicants in the main proceedings.

61.      In other words, the applicants in the main proceedings seem to take the view that the judgment in Rottmann (C‑135/08, EU:C:2010:104) requires, in a general way, that, irrespective of the connecting factor chosen by the legislature of a Member State in order to grant or withdraw the nationality of that Member State, national courts should examine all the individual circumstances in each case that will show that a genuine link has been maintained with that Member State, such as to enable the person concerned to retain the nationality of that State.

62.      I do not share that view.

63.      Above all, at the level of principles, I do not see anything to preclude, following a review of proportionality in the light of EU law, a provision of a law of a Member State of a general nature proving to be consistent with the principle of proportionality.

64.      In that regard and without claiming to be exhaustive, I shall merely mention the judgment of 6 October 2015, Delvigne (C‑650/13, EU:C:2015:648), which concerned the application of national law which had the effect of automatically depriving a citizen of the Union convicted of a criminal offence of his right to vote in elections to the European Parliament.

65.      After finding that the situation in that case fell within the scope of EU law, the Court agreed to review whether or not the deprivation of the right to vote was consistent with the right conferred by Article 39(2) of the Charter, and, in particular, with the principle of proportionality laid down in Article 52(1) of the Charter.

66.      In the context of examining the proportionality of the limitation on the right to vote, the Court held, first, that that limitation was proportionate in so far as it took into account the nature and gravity of the criminal offence committed and the duration of the penalty, noting that the deprivation of the right to vote was applicable, under the national legislation concerned, only to persons convicted of an offence punishable by a custodial sentence of between five years and life imprisonment. Secondly, the Court pointed out that the national law expressly provided for the possibility of convicted individuals applying for, and obtaining, the lifting of the penalty of loss of civic rights leading to the deprivation of the right to vote. The Court therefore concluded from this that the national legislation in question was not contrary to the principle of proportionality and held that Article 39(2) of the Charter did not preclude such legislation, which excluded, by operation of law, the category of citizens of the Union to which Mr Thierry Delvigne belonged from those entitled to vote in elections to the European Parliament.

67.      It may therefore be inferred from that case that the proportionality of a national legislation does not need to be examined in the light of individual circumstances in each case that would make it possible to disapply the limitation provided for by that legislation. In that regard, the Court merely pointed out that Mr Delvigne fulfilled the conditions for the application of the national legislation, namely that he had been convicted of an offence punishable by a custodial sentence of between five years and life imprisonment, without examining further whether the limitation of the right to vote was appropriate in relation to the individual sentence (12 years) which had been imposed on Mr Delvigne or a fortiori taking into consideration any mitigating circumstances relating to the situation of that individual.

68.      The review of observance of the principle of proportionality carried out in Rottmann (C‑135/08, EU:C:2010:104), despite undeniable ambiguities regarding its scope, does not appear to me to invalidate that approach.

69.      First of all, none of the grounds in Rottmann (C‑135/08, EU:C:2010:104) mentions that all the circumstances in each case are to be taken into consideration in order to determine whether a decision withdrawing naturalisation like the one at issue in that case is proportionate.

70.      On three occasions, in paragraphs 54, 55 and 56, first sentence, of that judgment, the Court made reference to the consequences that decision entailed for the person concerned.

71.      It is not particularly easy to grasp the relationship between those three paragraphs of the judgment in Rottmann (C‑135/08, EU:C:2010:104).

72.      Whilst paragraph 54 of that judgment sets out the immediate consequence of withdrawal of nationality for the person concerned, namely loss of citizenship of the Union, which seems understandable and logical, paragraphs 55 and 56, first sentence, of that judgment, by contrast, appear to envisage other types of more indirect — indeed ‘any possible’ — consequences apart from loss of citizenship of the Union, with regard to which the national court must carry out a review of the proportionality of the decision withdrawing naturalisation and also in the light not only of Article 20 TFEU but of EU law in general.

73.      In that regard, unless I am mistaken, in Rottmann (C‑135/08, EU:C:2010:104), besides the loss of citizenship of the Union, the only other direct consequence of the withdrawal of naturalisation which lay at the heart of the questions referred by the national court and which was plainly far from hypothetical was the risk that the person concerned would become stateless.

74.      As regards those two direct consequences of the decision withdrawing naturalisation in Rottmann (C‑135/08, EU:C:2010:104), the Court gave no indication to suggest that the decision might be disproportionate. Indeed, in paragraph 57 of the judgment in Rottmann (C‑135/08, EU:C:2010:104), the Court accepted that a Member State whose nationality had been acquired by deception was not bound, pursuant to Article 20 TFEU, to refrain from withdrawing naturalisation merely because the person concerned had not recovered the nationality of his Member State of origin and therefore citizenship of the Union. Moreover, in paragraph 58 of the judgment, somewhat curiously, the Court entrusted to the national court the task of determining itself the scope of the principle of proportionality, stating that it was for the latter to determine ‘whether before a decision withdrawing naturalisation takes effect, … observance of the principle of proportionality requires the person concerned to be afforded a reasonable period of time in order to try to recover the nationality of his Member State of origin’. (15)

75.      It is therefore difficult to see what other consequence(s) for the situation of the person concerned the national court was required to take into consideration when examining the proportionality of the decision withdrawing naturalisation at issue in Rottmann (C‑135/08, EU:C:2010:104), if even the direct consequences of that decision could not lead the German authorities to refrain from adopting that decision.

76.      It is perfectly possible to imagine that a decision withdrawing naturalisation that entails loss of citizenship of the Union might lead to a number of consequences for the situation of the person concerned or for the members of his family, as the Court stated in paragraph 56, first sentence, of the judgment in Rottmann (C‑135/08, EU:C:2010:104). For example, it could be envisaged that the loss of citizenship of the Union might lead to interruption or loss of payment of social benefits to the person concerned. Similarly, loss of citizenship of the Union might mean that the person concerned could no longer claim the right to reside in the territory of the Member State concerned, or even, in some situations, in the territory of the European Union. If that person has children who are nationals of that Member State, and has sole custody of them, the children might then find themselves in a situation similar to that considered in Ruiz Zambrano (C‑34/09, EU:C:2011:124).

77.      However, those consequences are a result not of the decision withdrawing the naturalisation of the person concerned but of subsequent administrative decisions which may or may not be adopted and which, in any event, are amenable to judicial remedies and, where appropriate, to review of proportionality, including in the light of EU law.

78.      Accordingly, I find it difficult to see why, when examining the proportionality of the decision withdrawing nationality in the light of EU law, the national court concerned should have to take into consideration such indirect, even hypothetical, consequences if they cannot, in any event, cause it to annul that decision or to find that the national authorities should not have adopted that decision.

79.      Thus, to take one of the examples mentioned earlier, if the person concerned, who is likely to lose his citizenship of the Union, and the members of his family, who are themselves citizens of the Union, were in a situation similar to that considered in Ruiz Zambrano (C‑34/09, EU:C:2011:124), that would not mean that the Member State concerned would have to refrain, in respect of the person concerned, from adopting the decision withdrawing his nationality, but rather that it would have to ensure that the person concerned can continue to reside in the territory of the European Union as a member of the family of citizens of the Union.

80.      Accordingly, there are two alternatives: either the adoption of a decision withdrawing nationality can be ‘neutralised’ because of the loss of citizenship of the Union it entails — an action which, of course, raises a number of difficulties in the light of the complementary nature of that status in relation to nationality of the Member States, as provided for in Article 9 TEU and Article 20(1) TFEU, (16) but which, in my view, is not impossible (17) — or the adoption of such a decision cannot be ‘neutralised’ by the loss of citizenship of the Union — but then I find it difficult to see why, as a result of indirect consequences that are subsidiary or even hypothetical with regard to the situation of the person concerned, and less serious than the loss of that fundamental status and of the rights attaching thereto, the decision withdrawing nationality cannot be adopted.

81.      I trust the Court will not misinterpret what I am saying. It is not my intention to exempt Member States from a review of the proportionality of a decision withdrawing nationality or of a measure, such as those at issue in the main proceedings, establishing the loss of nationality of nationals of a Member State, which entail the loss of citizenship of the Union.

82.      However, that review must, in my view and according to case-law, be limited to determining whether the national measure in question, which has as a direct consequence the loss of citizenship of the Union, is suitable for attaining the public-interest objective it pursues and whether that objective cannot be attained by less restrictive measures, that is to say, whether the measure at issue does not go further than is necessary in order to attain that public-interest objective. (18)

83.      Paragraph 59 and the operative part of the judgment in Rottmann (C‑135/08, EU:C:2010:104), which, in general terms, make compatibility with EU law, inter alia with Article 17 EC (now Article 20 TFEU), of a decision withdrawing naturalisation subject to the ‘principle of proportionality’, support that interpretation.

84.      In any event, the review of proportionality which the Court called on the national court to undertake in Rottmann (C‑135/08, EU:C:2010:104) does not, in my view, include examination of all the circumstances specific to each individual situation which, despite fulfilment of the conditions for the application of the national legislation that lead to the withdrawal of nationality, are capable of demonstrating that a genuine link has been maintained with the Member State concerned.

85.      In that regard, if at this stage we look solely at the factors expressly listed in the second sentence of paragraph 56 of the judgment in Rottmann (C‑135/08, EU:C:2010:104), I note that the Court called on the national court to determine, in particular, whether the loss of the rights enjoyed by every citizen of the Union ‘is justified in relation to the gravity of the offence committed by that person, to the lapse of time between the naturalisation decision and the withdrawal decision and to whether it is possible for that person to recover his original nationality.’

86.      Clearly, although the second sentence of paragraph 56 of the judgment in Rottmann (C‑135/08, EU:C:2010:104) is worded in general terms, the factors that the Court identified as requiring to be examined by the national court are not necessarily capable of being applied to all situations in which loss of the nationality of a Member State and of citizenship of the Union are at issue. In particular, the review of proportionality must be carried out on the basis of the grounds for the withdrawal of nationality and of citizenship of the Union.

87.      That said, examination of the three factors mentioned in the second sentence of paragraph 56 of the judgment in Rottmann (C‑135/08, EU:C:2010:104) does not, to my mind, support the argument put forward by the applicants in the main proceedings that all the circumstances of each case must be taken into consideration in the examination of the proportionality of a national measure withdrawing the nationality of a Member State from an individual.

88.      That is clearly the case as regards the request to the national court to determine whether the loss of rights attaching to the status of citizen of the Union was ‘justified in relation to the gravity of the offence committed’. Examination of that factor, pertaining to the ground (deception) for the decision withdrawing naturalisation in Rottmann (C‑135/08, EU:C:2010:104), merely requires that a correlation be established between the loss of rights attaching to the status of citizen of the Union and the sufficiently serious nature of the offence committed by the person concerned, which may be carried out perfectly well in abstracto and does not therefore involve an examination in concreto. (19) Thus, in an extreme — and I hope purely hypothetical — case, where the legislation of a Member State provides for withdrawal of an individual’s naturalisation entailing loss of citizenship of the Union as a result of a road traffic offence, the disproportionate nature of that measure would be clear because of the disparity between the low degree of gravity of the offence and the dramatic consequence of losing citizenship of the Union. Such a review would by no means require the individual situation of the person to be taken into consideration.

89.      That is also undoubtedly so where the national court examines whether it is possible for the person concerned, who is deprived of the nationality of a Member State, ‘to recover his original nationality’. That examination may perfectly well be carried out solely in the light of the possibilities provided for by the relevant national provisions, regardless of whether the circumstances specific to the individual are examined. Moreover, it is interesting to note that, although that passage from the judgment in Rottmann (C‑135/08, EU:C:2010:104) appears in a paragraph which recalls the importance which primary law attaches to the status of citizen of the Union, the Court does not focus on either the need for the person concerned to retain that status (20) or the fact that the person concerned may actually recover his original — in that case Austrian — nationality, which in Rottmann (C‑135/08, EU:C:2010:104) would have enabled the applicant to recover citizenship of the Union also. (21)

90.      That, in my view, is also the case for the examination, called for by the Court in the second sentence of paragraph 56 of the judgment in Rottmann (C‑135/08, EU:C:2010:104), of the ‘lapse of time between the naturalisation decision and the withdrawal decision’, although, I must admit, that is more doubtful. The examination that the national court is requested to carry out raises doubts as to the consequences which the court should infer from the lapse of time. It is not clear whether the lapse of time might have prevented the actual adoption of the decision withdrawing nationality or might possibly, in view of the specific circumstances in Rottmann (C‑135/08, EU:C:2010:104), only have had an influence on whether or not that decision was to have retroactive effect. In Rottmann (C‑135/08, EU:C:2010:104), the lapse of time between the naturalisation decision and the withdrawal decision was approximately a year and a half. Moreover, the relevant German law provided that an administrative act obtained by fraud was, in principle, to be withdrawn with retroactive effect, (22) which gave the national court concerned discretion to take into consideration certain factors relating to the conduct of the person concerned and of the administration during the lapse of time, including the latter’s lack of diligence in establishing deception. The Court did not, however, give clear guidance suggesting that the lapse of time could ‘neutralise’ the acquisition of nationality by deception and, consequently, adoption of the retroactive decision withdrawing naturalisation. In other words, it is by no means clear from Rottmann (C‑135/08, EU:C:2010:104) that the national court was being called on to determine whether, despite deception on the part of the person concerned, the latter had, in view of the specific circumstances, established during the lapse of time between the naturalisation decision and the decision withdrawing naturalisation, a sufficiently strong link with the Federal Republic of Germany so as to preclude the withdrawal of naturalisation.

91.      Consequently, in view of both Delvigne (C‑650/13, EU:C:2015:648) and Rottmann (C‑135/08, EU:C:2010:104), I take the view that, in the main proceedings, review of the proportionality of Article 15(1)(c) of the Law on Netherlands nationality should be carried out in abstracto and, in any event, regardless of the consequences and individual circumstances that would have the effect of disapplying the conditions for loss of nationality chosen by the Netherlands legislature.

92.      I now come to the examination of the proportionality of Article 15(1)(c) of the Law on Netherlands nationality.

93.      In that regard, it should be noted, first, that application of that article does not necessarily lead to loss of citizenship of the Union. As I pointed out above, the loss of Netherlands nationality laid down in that article equally applies to nationals of the Kingdom of the Netherlands who are also nationals of another Member State and who reside in a third country. Despite the loss of Netherlands nationality, those persons retain citizenship of the Union.

94.      Secondly, as the referring court noted, Article 15(4) of the Law on Netherlands nationality provides several possibilities for interrupting the 10‑year period of uninterrupted residence in a third country, by means of simple steps. That period is interrupted, and hence a new 10-year period starts to run for the person concerned, where the latter has obtained either a declaration regarding the possession of Netherlands nationality or a travel document (passport) or a Netherlands identity card.

95.      By being issued one of those documents the person concerned may, on his own initiative, avoid the loss of Netherlands nationality and, where relevant, the loss of citizenship of the Union.

96.      Irrespective even of the loss of nationality, it would seem to be far from unreasonable or disproportionate to require a national of a Member State to renew, from the date of expiry of his passport or national identity card, one of those documents. (23)

97.      That point is all the more valid where the person resides for a significant period of time in a third country and the link with the Member State of origin may have weakened. It is in everyone’s interests to have valid identity/travel documents, especially since the issuing of one of those documents enables the person concerned to retain his nationality and, where relevant, citizenship of the Union.

98.      Where a Netherlands national, within the 10-year period of uninterrupted residence in a third country, applies for one of the three documents mentioned in Article 15(4) of the Law on Netherlands nationality to be issued, the Netherlands legislature presumed that that person wishes to maintain a genuine link with the Netherlands.

99.      By contrast, where the person concerned fails to take steps to obtain one of those documents during the 10-year period of uninterrupted residence in a third country provided for in Article 15(1)(c) of that law, the Netherlands legislature presumed that that link has been lost. (24)

100. Such presumptions do not appear to go further than is necessary in order to attain the objective pursued by the Netherlands legislature.

101. Thirdly, the loss, by operation of law, of Netherlands nationality and, where relevant, of citizenship of the Union is not irreversible. Under Article 6(1)(f) of the Law on Netherlands nationality, where a person has lost his Netherlands nationality, he is able to acquire it anew under more favourable conditions than a national who has never held Netherlands nationality. As the Court stated in the second sentence of paragraph 56 of the judgment in Rottmann (C‑135/08, EU:C:2010:104) and as with the review of observance of the principle of proportionality which it carried out in the judgment of 6 October 2015, Delvigne (C‑650/13, EU:C:2015:648), I consider that the possibility of recovering the rights attaching to the status of citizen of the Union contributes to the proportionality of the national legislation at issue in the present case.

102. In the present case, none of the three adult applicants challenges the fact that they meet the conditions for the application of Article 15(1)(c) of the Law on Netherlands nationality and that, consequently, they must lose their Netherlands nationality and, since they are not nationals of another Member State, their citizenship of the Union. (25)

103. According to the information supplied by the referring court, the applicants in the main proceedings, astonishingly, waited between six and 10 years before applying for renewal of their passports, all of them having submitted their applications for renewal in the course of 2014, although, under Article 15(1)(c) of the Law on Netherlands nationality, they had all lost their Netherlands nationality from the spring of 2013.

104. As I stated above, the applicants in the main proceedings complain that the Law on Netherlands nationality precludes national courts from taking into consideration individual circumstances which demonstrate that they have maintained a genuine link with the Netherlands, despite the criterion adopted by the Netherlands legislature in Article 15(1)(c) of the Law on Netherlands nationality. In other words, they consider that the principle of proportionality requires the national court to take into account not only the individual circumstances that are involved in establishing that the conditions for the application of Article 15(1)(c) of the Law on Netherlands nationality are met, but also, and especially, the individual circumstances that relate to other connecting factors which show that a purported genuine link has been maintained with the Netherlands, such as the ability to speak the Dutch language, the maintenance of family and/or emotional links in that Member State, and the exercise of the right to vote in Netherlands elections.

105. However tempting it may appear, and beyond the discussion about the scope of the judgments in Rottmann (C‑135/08, EU:C:2010:104) and Delvigne (C‑650/13, EU:C:2015:648), that argument, to my mind, has particularly dangerous consequences, inter alia as regards the allocation of competences between the Member States and the European Union.

106. Under the pretext of requesting an examination of observance of the principle of proportionality in EU law, that argument ultimately amounts to seeking to require the national court to dismiss the ground for loss of nationality chosen by the national legislature, in accordance with international law and without conflicting with EU law, in favour of criteria showing a connection with the Member State concerned, which although totally possible from a theoretical point of view or from the point of view of another Member State, are not ones which the national legislature adopted as being relevant in order to show that a genuine link with the Member State concerned has been maintained.

107. According to case-law, Member States have the competence to lay down the conditions for acquisition and loss of nationality and, under Article 9 TEU and Article 20(1) TFEU, citizenship of the Union is additional to and does not replace national citizenship. Support for the arguments of the applicants in the main proceedings would also lead the European Union to infringe the duty, laid down in Article 4(2) TEU, to respect the national identities of the Member States, of which the composition of the national body politic is clearly an essential element. (26)

108. As I pointed out above, the judgment in Rottmann (C‑135/08, EU:C:2010:104) does not support the line of argument put forward by the applicants in the main proceedings either. That judgment cannot in my view be interpreted as requiring the national court, when examining observance of the principle of proportionality, to determine whether the adoption of a decision withdrawing the nationality of a Member State, based on a public-interest objective pursued by national rules, can be excluded due to the existence of circumstances specific to the person concerned which demonstrate that a genuine link has been maintained with the Member State concerned, irrespective of the ground on which that decision was taken.

109. Moreover, and as a corollary, I would point out that the need for, and proportionality of, a national measure that pursues a public-interest objective are not excluded merely because one Member State has chosen a system of protection different from that adopted by another Member State (27) or because there are other conceivable measures which could attain that objective but which the national legislature, for one reason or another, has decided were not appropriate for so doing.

110. In addition, acceptance of the line of argument put forward by the applicants in the main proceedings in the present case would mean that the national court would have to establish, without any specific guidance on the part of the national legislature, the relevant criteria showing a connection with the Member State concerned, their scope and their relative importance.

111. For example, if the ability to use the Dutch language were adopted as a relevant criterion, in what way would the national court have to take account of the fact that Ms Tjebbes states in her written observations that she does not speak Dutch fluently and, if appropriate, weight that criterion against the number of journeys she has made between Canada and the Netherlands over the last few years or, where relevant, any family ties, the closeness of which is not specified, she maintains in that Member State?

112. Likewise, in Ms Koopman’s situation, who claims a perfect command of both written and spoken Dutch, and who appears to travel regularly to the Netherlands: should the national court also take into account — and, if so, to what extent — the fact that, according to Ms Koopman’s observations, her son, who became an adult before the spring of 2013 has taken steps, unlike Ms Koopman herself, to retain Netherlands nationality?

113. Requiring national courts to do this would expose individuals to situations of legal uncertainty. In any event, I take the view that if, contrary to what I propose, the Court were to support the argument put forward by the applicants in the main proceedings, the Court itself would have to determine the scope of the principle of proportionality and, accordingly, indicate to the referring court the relevant criteria showing a connection with the Member State concerned which the referring court would have to take into consideration, and the latter would be responsible for determining whether they are met in each of the situations in the main proceedings.

114. I would not encourage the Court to go in that direction since it would encroach too far on the competence of the Member States to lay down the conditions for loss of nationality.

115. For all those reasons, in my view, Article 15(1)(c) of the Law on Netherlands nationality does not infringe the principle of proportionality, as protected under EU law.

116. Lastly, that conclusion is not affected by the need to ensure the right of every person to respect for his or her private and family life under Article 7 of the Charter.

117. The application of Article 15(1)(c) of the Law on Netherlands nationality by no means deprives Netherlands nationals who have lost their Netherlands nationality and, where relevant, citizenship of the Union, of enjoyment of their private and family life. In particular, they still enjoy the right to reside in the territory of the third country whose nationality they hold, continue to travel and move around freely by virtue of the travel documents issued by that third country and are, within the limits of the rules governing the entry of foreign nationals, allowed into the territory of any other country, including Member States of the European Union. Such individuals also continue to have full enjoyment of their family life, without the risk of having to leave the territory of the third country in which they reside. This holds true in all cases. In other words, it does not require an examination in concreto of the impact of the loss of nationality, and where relevant, the loss of citizenship of the Union on the individual situation of each person concerned.

118. Accordingly, I propose that the answer to the first part of the question from the referring court should be that Article 20 TFEU and Article 7 of the Charter do not preclude a legislative provision such as Article 15(1)(c) and (4) of the Law on Netherlands nationality, which provides that an adult, who is also a national of a third country, loses, by operation of law, the nationality of a Member State, and consequently loses citizenship of the Union, on the ground that, for an uninterrupted period of 10 years, that person had his or her principal residence abroad and outside the European Union.

C.      Compatibility with Article 20 TFEU, and Article 24 of the Charter, of the loss of nationality by Netherlands nationals who are minors, as provided for in Article 16(1)(d) of the Law on Netherlands nationality

119. The second part of the question from the referring court relates to the loss of nationality by Netherlands nationals who are minors, as provided for in Article 16(1)(d) of the Law on Netherlands nationality and, in the main proceedings, concerns only the situation of Ms Koopman’s daughter, Ms Duboux. As with the examination of Article 15(1)(c) of that law, it is necessary to determine whether the loss of nationality laid down in Article 16(1)(d) of that law pursues a public-interest objective and does not go further than is necessary in order to attain of that objective.

1.      The public-interest objective pursued by Article 16(1)(d) of the Law on Netherlands nationality

120. Under Article 16(1)(d) of the Law on Netherlands nationality, a minor loses his Netherlands nationality if one of his parents loses that nationality pursuant to Article 15(1)(c) of that law and provided, according to the referring court, the minor does not become stateless. (28)

121. With regard to the public-interest objective pursued by Article 16(1)(d) of the Law on Netherlands nationality, the referring court states that it follows from the legislative history of the article that it was intended to restore unity of nationality within the family.

122. In that regard, it should be noted that Article 16(1)(d) of the Law on Netherlands nationality draws on Article 7(2) of the European Convention on Nationality, which states that a State Party to that convention may provide for the loss of its nationality by children, one of whose parents loses that nationality. (29) In addition, the Second Protocol amending the (European) Convention on the Reduction of Cases of Multiple Nationality and Military Obligations in Cases of Multiple Nationality, signed at Strasbourg on 2 February 1993, (30) mentions, in its third recital, encouragement of unity of nationality within the same family.

123. It is true that, even at international level, doubts have been cast on the legitimacy of such an objective, because of the need to recognise autonomous procedural and substantive rights for minors in relation to their parents. (31)

124. Without going so far as to recognise the existence of such rights, the Netherlands Government stated several times in the observations it submitted in the present case that the objective of unity of nationality within the family must include taking into consideration the (best) interests of the child, as recognised in the context of the application of Article 7(2) of the European Convention on Nationality. (32) The Netherlands Government adds that the best interests of the child, enshrined in Article 24(2) of the Charter, (33) were moreover taken into account by the national legislature when it provided, in Article 16(2) of the Law on Netherlands nationality, for a number of exceptions to loss of nationality in the case of minors.

125. I share the position of the Netherlands Government that the objective of unity of nationality within the family must necessarily involve taking into consideration the best interests of the child. Taking that principle into consideration is all the more important where, by losing his Netherlands nationality, the minor also risks being deprived of citizenship of the Union.

126. In the light of those considerations, the objective of ensuring or restoring unity of nationality within the family, whilst also taking into account the best interests of the child, constitutes to my mind a legitimate objective which may in principle justify the loss by a minor of the nationality of a Member State, a loss that may in turn entail loss of citizenship of the Union.

127. It is appropriate, however, to determine whether the measure whereby the Netherlands legislature provided for attaining that objective is consistent with the principle of proportionality.

2.      The proportionality of Article 16(1)(d) of the Law on Netherlands nationality

128. According to the Netherlands Government, taking into consideration the best interests of a child who is a citizen of the Union does not mean that the loss of Netherlands nationality, entailing the loss of citizenship of the Union, may never happen. It adds, in essence, that where a parent has lost a genuine link with the Netherlands, it may reasonably be presumed that in principle the child no longer has a genuine link with that Member State. That argument would explain why loss of nationality by minors is in principle automatic, unless it comes within the exceptions provided for in Article 16(2) of the Law on Netherlands nationality.

129. I do not find this argument convincing.

130. It is not a question of disputing that the best interests of a child who is a citizen of the Union may preclude in principle loss of the nationality of a Member State and consequently loss of citizenship of the Union.

131. However, first, the Netherlands legislature started from the presumption that unity of nationality within the family is always in the best interests of the child, save in the exceptional cases which the legislature itself allowed.

132. Secondly, the Netherlands legislature does not appear to have taken any account of the fact that citizens of the Union who are minors enjoy that status autonomously. It is clear however that the status of citizen of the Union is not reserved for adults and that minors are not second-class citizens of the Union. (34) Minors, essentially, enjoy the same rights deriving from that status, irrespective of the fact that exercise of those rights is dependent generally on the persons who have parental authority over them. Minors do not therefore possess citizenship of the Union derived from that of their parents, where the latter are themselves citizens of the Union, but they enjoy the status of citizen of the Union autonomously.

133. In my view, the autonomy of the citizenship of the Union enjoyed by minors and the need to take into consideration the best interests of the child mean that, in the application of legislation of a Member State which entails, for nationals of that State who are minors, loss of nationality and loss of citizenship of the Union, such minors must be able to enjoy the same procedural and substantive rights as are granted to adults.

134. However, as the referring court pointed out, children who are citizens of the Union, unlike adults, do not have the possibility of avoiding loss of nationality by applying for the documents provided for by Article 15(4) of the Law on Netherlands nationality.

135. A parent who is a Netherlands national may take such steps.

136. Nevertheless, those steps taken on behalf of the child are invariably dependent upon the parent taking parallel steps on his own behalf. Otherwise, loss of nationality for the parent automatically entails loss of nationality for the child.

137. Thus, a parent being a citizen of the Union, who applied for and obtained the renewal of a passport solely for his child, a citizen of the Union, in 2012, that is to say, before 1 April 2013, but who lost Netherlands nationality after that date, would find that his child had also automatically lost both that nationality and citizenship of the Union with effect from that date, although, formally, that child holds a passport issued by the Netherlands authorities for five years, until 2017, which might also mean that that child could enjoy the effects of the act interrupting the 10-year period provided for in Article 15(4) of the Law on Netherlands nationality, that is to say until 2022 and, consequently, retain Netherlands nationality and citizenship of the Union, at least until that date.

138. It is certainly not inconceivable that such a situation might arise.

139. It is in fact perfectly conceivable that, before the expiry of the 10-year period, the parent of Netherlands nationality of a Netherlands minor who is a citizen of the Union, where appropriate with the latter’s agreement, might consider that it is in the best interests of the child to retain Netherlands nationality and hence citizenship of the Union, before the parent concerned is himself obliged to renew his passport or identity card in order to retain his own Netherlands nationality.

140. Moreover, it is also possible that, for a variety of reasons, the minor lives separately from his parent within the European Union or indeed the Netherlands.

141. In the first place, the Law on Netherlands nationality contains no provision excluding in such cases the minor’s automatic loss of Netherlands nationality due to the parent’s loss of nationality, although that would be in the best interests of the child who is a citizen of the Union.

142. As the referring court stated and I reiterate, Article 15(3) and (4) of the Law on Netherlands nationality, which allows interruption of the 10-year period of residence in a third country, applies only in the case of adults. In addition, whilst the Netherlands legislature recognised that the objective of unity of nationality within the family may permit exceptions, none of the exceptional circumstances provided for by Article 16(2) of the Law on Netherlands nationality apply in the cases described above.

143. Secondly, by not taking into account that type of situation the Netherlands legislature presupposes that a minor’s citizenship of the Union is invariably dependent upon that of an adult, save in some of the exceptional situations provided for in Article 16(2) of the Law on Netherlands nationality.

144. Measures that would be less damaging to the best interests of the child and the latter’s status as citizen of the Union would to my mind be, inter alia, a general clause enabling the national court to take into account those interests and that status in all cases in which the relevant provisions of the Law on Netherlands nationality apply, and/or an option for Netherlands nationals to take steps to interrupt the 10-year period solely for their children of Netherlands nationality who are citizens of the Union.

145. What is more, the fact that upon becoming an adult a child may recover Netherlands nationality on certain conditions cannot, on its own, make up for the fact that while a minor that person would not have had to lose the nationality in question if the best interests of the child and his status of citizen of the Union had been duly taken into consideration.

146. Consequently, I consider that, by failing to provide that the best interests of a child who is a citizen of the Union should be taken into consideration in any decision that might lead to that child losing his citizenship of the Union, save in the few exceptional cases provided for by Article 16(2) of the Law on Netherlands nationality, the Netherlands legislature went beyond what is necessary in order to attain the objective of unity of nationality within the family whilst taking into account the best interests of the child.

147. That conclusion, which is consistent with the national legislature’s competence in principle to lay down the conditions for loss of nationality, clearly does not conflict with the conclusion I propose to adopt in respect of adults. It is not a matter here of dismissing the criterion for loss of the nationality of the Member State concerned chosen by the national legislature in favour of a substitute criterion that was not adopted by that legislature, but merely of reviewing whether or not the measures adopted by that legislature in order to attain the objective it wishes to pursue go further than is necessary in order to attain it.

148. In other words, in carrying out that review there is no need to take into consideration either individual circumstances which show that the person concerned maintains a link with the Member State concerned based on a criterion not adopted by the national legislature — allowing for the criterion chosen by the national legislature in the context of its competence to lay down the conditions for loss of nationality to be disapplied — or any specific and individual consequences that loss of citizenship of the Union would entail. (35)

149. In the light of those considerations, I propose that the answer to the second part of the question from the referring court should be that Article 20 TFEU and Article 24 of the Charter preclude a legislative provision such as Article 16(1)(d) and (2) of the Law on Netherlands nationality, under which, save in exceptional cases, a minor loses, by operation of law, the nationality of his or her Member State and consequently loses citizenship of the Union, as a result of the loss of nationality by his or her parent.

D.      Limitation of the temporal effects of the judgment of the Court

150. At the hearing, the Netherlands Government requested the limitation of the temporal effects of the judgment to be delivered in the event that the Court were to find Articles 15(1)(c) and 16(1)(d) of the Law on Netherlands nationality to be disproportionate.

151. That request cannot be successful, in my view, even if the Court were to make such a finding.

152. It should be noted that two essential criteria must be fulfilled before such a limitation can be imposed, namely that those concerned should have acted in good faith and that there should be a risk of serious difficulties. (36)

153. More specifically, it is clear from the case-law of the Court that the financial consequences which might ensue for a Member State from a preliminary ruling do not in themselves justify limiting the temporal effects of the ruling.

154. The Court has taken that step only in very specific circumstances, notably where there was a risk of serious economic repercussions owing in particular to the large number of legal relationships entered into in good faith on the basis of rules considered to be validly in force and where it appeared that individuals and national authorities had been led to adopt practices which did not comply with EU law by reason of objective, significant uncertainty regarding the implications of EU-law provisions, to which the conduct of other Member States or the Commission may even have contributed. (37)

155. In support of its application, the Netherlands Government has not supplied any evidence of possible serious difficulties or serious economic repercussions that would be likely to lead to acknowledgement by the Court of the incompatibility with EU law of the legislative provisions at issue in the main proceedings. In particular, the Netherlands Government merely stated briefly that there were many Netherlands citizens who had lost Netherlands nationality over a number of years, without providing any evidence to show the number of persons concerned or what might be the difficulties and possible economic consequences the Netherlands might face as a result of the recovery of Netherlands nationality by the individuals concerned.

156. I therefore propose that in any case the Netherlands Government’s request for the Court to limit the temporal effects of the judgment to be delivered should be rejected.

IV.    Conclusion

157. For all the above considerations, I propose that the request for a preliminary ruling from the Raad van State (Council of State, Netherlands) should be answered as follows:

(1)      Article 20 TFEU and Article 7 of the Charter of Fundamental Rights of the European Union must be interpreted as not precluding a legislative provision such as Article 15(1)(c) and (4) of the Rijkswet op het Nederlanderschap (Law on Netherlands nationality), which provides that an adult, who is also a national of a third country, loses, by operation of law, the nationality of a Member State and consequently loses citizenship of the Union,on the ground that, for an uninterrupted period of 10 years, that person had his or her principal residence abroad and outside the European Union.

(2)      Article 20 TFEU and Article 24 of the Charter of Fundamental Rights must be interpreted as precluding a legislative provision such as Article 16(1)(d) and (2) of the Law on Netherlands nationality, which provides that, save in exceptional cases, a minor, who is also a national of a third country, loses, by operation of law, the nationality of his or her Member State and consequently loses citizenship of the Union, as a consequence of the loss of nationality of his or her parent.

1      Original language: French.

2      That expression refers in particular to the territories of the Netherlands Antilles.

3      Treaty Series, Vol. 989, p. 175. The Kingdom of the Netherlands ratified the Convention on the Reduction of Statelessness on 13 May 1985.

4      ETS No166. The Kingdom of the Netherlands ratified the convention on 21 March 2001 and it entered into force in the territory of that Member State on 1 July 2001.

5      See judgments of 20 September 2001, Grzelczyk (C‑184/99, EU:C:2001:458, paragraph 31); of 17 September 2002, Baumbast and R (C‑413/99, EU:C:2002:493, paragraph 82); of 19 October 2004, Zhu and Chen (C‑200/02, EU:C:2004:639, paragraph 25); of 2 March 2010, Rottmann (C‑135/08, EU:C:2010:104, paragraph 43); of 8 March 2011, Ruiz Zambrano (C‑34/09, EU:C:2011:124, paragraph 41); and of 13 September 2016, Rendón Marín (C‑165/14, EU:C:2016:675, paragraph 69).

6      See point 13 of the Opinion of Advocate General Poiares Maduro in Rottmann (C‑135/08, EU:C:2009:588).

7      Provided, of course, that the law of the other Member State is not strictly identical to the Law on Netherlands nationality, in which case, there would be a risk of those persons becoming stateless. That risk does not appear likely, however.

8      See, to that effect, judgment of 2 March 2010, Rottmann (C‑135/08, EU:C:2010:104, paragraphs 39 and 45).

9      That also seems to follow from Rottmann (C‑135/08, EU:C:2010:104), in which the Court only interpreted Article 17 EC (now Article 20 TFEU) although it had been asked about the interpretation of ‘Community law’ generally, which might have led it to include Article 18 EC (now Article 21 TFEU) in its answer.

10      See, in particular, point 89 of my Opinion in X and X (C‑638/16 PPU, EU:C:2017:93).

11      Rottmann (C‑135/08, EU:C:2010:104, paragraph 55) (italics added).

12      Rottmann (C‑135/08, EU:C:2010:104, paragraph 56) (italics added).

13      See, to that effect, judgment of 2 March 2010, Rottmann (C‑135/08, EU:C:2010:104, paragraphs 51 to 54).

14      See paragraphs 69 and 70 of the Explanatory Report to the European Convention on Nationality. That report is available in English at: https://rm.coe.int/16800ccde7

15      Italics added. For the Court, the principle of proportionality therefore does not require either that a procedure designed to prevent loss of citizenship of the Union should be put in place or that the procedure for deprivation of naturalisation should be suspended until the person concerned has actually recovered his original nationality, enabling him to retain citizenship of the Union.

16      It will be recalled that the last sentence of Article 9 TEU and Article 20(1) TFEU both provide that ‘citizenship of the Union shall be additional to and not replace national citizenship’.

17      Whether for a reason that is regarded as unlawful in the light of EU law or because of the disproportionate nature of the national measure, as I propose should be found with regard to the application of Article 16(1)(d) of the Law on Netherlands nationality to minors: see points 128 to 149 of this Opinion.

18      See, to that effect, judgments of 22 December 2010, Sayn-Wittgenstein (C‑208/09, EU:C:2010:806, paragraphs 90 and 93), and of 2 June 2016, Bogendorff von Wolffersdorff (C‑438/14, EU:C:2016:401, paragraphs 72 and 74).

19      Like the review carried out by the Court in the judgment of 6 October 2015, Delvigne (C‑650/13, EU:C:2015:648).

20      Or the need to avoid the person concerned becoming stateless: see, inter alia, to that effect, Marinai, S., Perdita della cittadinanza e diritti fondamentali: profili internazionalistici ed europei, Giuffrè, Milano, 2017, p. 162.

21      Which, as I mentioned above, is confirmed in paragraphs 57 and 58 of the judgment in Rottmann (C‑135/08, EU:C:2010:104).

22      See Rottmann (C‑135/08, EU:C:2010:104, paragraph 8).

23      The same applies with regard to the issuing of a declaration regarding possession of Netherlands nationality, which may be applied for, without the person concerned needing to go anywhere, by means of a form available on the Netherlands Government website.

24      I would point out that paragraph 71 of the Explanatory Report to the European Convention on Nationality also states that possible evidence of the lack of a genuine link with a State Party may be the omission, inter alia, of an application for identity or travel documents or of a declaration expressing the desire to conserve the nationality of the State Party.

25      That means, of course that the national court was satisfied, in the light of the circumstances specific to each of the three applicants in the main proceedings, that the conditions for the application of Article 15(1)(c) of the Law on Netherlands nationality were met. In that regard, there is no doubt in my mind that if the Minister had, for example, omitted in a particular case to take into consideration an act interrupting the 10-year period the national court would have had to annul the decision not to issue the passport requested on the ground that the criteria laid down in Article 15(1)(c) of the Law on Netherlands nationality were not met. Similarly, if an individual states that it has been impossible for him to apply for renewal of his passport within a reasonable period following expiry of his old passport, or to apply for one of the two other documents to be issued that allow the 10-year period laid down in Article 15(1)(c) of the Law on Netherlands nationality to be interrupted, that situation must be examined by the national court. Since no-one is required to do the impossible, the national court must ensure, in the light of the evidence supplied by the person concerned, that the contention that it was impossible for him to obtain the documents mentioned in Article 15(1)(c) of the Law on Netherlands nationality is well founded.

26      See, to that effect, Opinion of Advocate General Poiares Maduro in Rottmann (C‑135/08, EU:C:2009:588, point 25).

27      See, to that effect, judgment of 2 June 2016, Bogendorff von Wolffersdorff (C‑438/14, EU:C:2016:401, paragraph 73 and the case-law cited).

28      According to Article 14(6) of the Law on Netherlands nationality.

29      It should also be noted that Article 6 of the Convention on the Reduction of Statelessness does not preclude this ground for loss of nationality by minors.

30      ETS No 149. That protocol was ratified by only two States, namely the Italian Republic and the Kingdom of the Netherlands.

31      See, inter alia, the report prepared by Waltraud Fuchs-Mair and Michaela Staudigl, entitled ‘European Convention on Nationality — Best Practices for Children’, Third European Conference on Nationality, held in Strasbourg on 11 and 12 October 2004 [doc. CJ-S-NAT (2008) 2].

32      See paragraph 75 of the Explanatory Report to the European Convention on Nationality, which states that ‘when applying [Article 7(2) of that convention], States Parties should in any case be guided by the best interests of the child’.

33      It will be recalled that Article 24(2) of the Charter provides that in all actions relating to children, whether taken by public authorities or private institutions, the child’s best interests must be a primary consideration. The Court has held on several occasions that it is ensuring observance of the obligation to take into consideration the best interests of the child as recognised by Article 24(2) of the Charter: see, inter alia, judgments of 13 September 2016, Rendón Marín (C‑165/14, EU:C:2016:675, paragraphs 76 to 78), and of 10 May 2017, Chavez-Vilchez and Others (C‑133/15, EU:C:2017:354, paragraph 60).

34      The case-law resulting, inter alia, from the judgment of 8 March 2011, Ruiz Zambrano (C‑34/09, EU:C:2011:124) provides a particularly clear illustration of this.

35      Thus, irrespective of the merits of her claim, the fact that Ms Duboux contends that the loss of Netherlands nationality and of citizenship of the Union would prevent her from going to study in the European Union since Swiss nationals are not entitled to an Erasmus scholarship is of no relevance, in my view, in the context of an examination of the proportionality of Article 16(1)(d) of the Law on Netherlands nationality.

36      See judgment of 19 October 2017, Paper Consult (C-101/16, EU:C:2017:775, paragraph 65 and the case-law cited).

37      See, to that effect, judgment of 19 October 2017, Paper Consult (C-101/16, EU:C:2017:775, paragraph 66 and the case-law cited).