Jules Lepoutre The 1997 European Convention on Nationality notably reduces the scope of authorised grounds. The articles 7(1)(c) and (d) only allow revocation (ex lege or at the initiative of the State) in case of “voluntary service in a foreign military force” or a “conduct seriously prejudicial to the vital interests of the State Party.” In both cases, according to article 7(3), revocation cannot lead to statelessness. This is a very strong constraint on state power, especially when considering the Explanatory Report to the Convention which states that the standard of “vital interest” (shared with the 1961 Convention on the Reduction of Statelessness) “notably includes treason and other activities directed against the vital interests of the State concerned (for example work for a foreign secret service) but would not include criminal offences of a general nature, however serious they might be.” As a consequence, only disloyalty, when properly established, is a ground for deprivation in the 1997 Convention. States are not allowed to protect the ‘merit’ of the status of citizenship by revoking the nationality of a common criminal, for instance. In the K2 v. the United Kingdom case, the European Court of Human Rights ruled in 2017 that an “arbitrary” revocation of citizenship might, “in certain circumstances,” interfere with the “individual’s right to respect for family and private life” (which was an extension of the Ramadan case ruled in 2016, see below 3.2.4.[a]).74 The court, therefore, raised two general questions: one about the “arbitrary” nature of the revocation and the other about the “consequences” of revocation for the applicant. First, the court assessed the arbitrary nature of this deprivation by considering three issues: whether it was carried out in accordance with the law, the diligent and swift action of the authorities and the inclusion of procedural safeguards. Second, as for the consequences of the measure, the court examined the proportionality of the decision, taking into account the applicant’s potential statelessness and private and family life, especially his capacity to live with his wife and children. The court finally did not find any violation of article 8 of the European Convention of Human Rights. Moreover, the complaint under article 14 of the Convention – the principle of non-discrimination – was rejected because it was not raised during the British judicial review proceeding. Questions of discrimination between single and dual nationals, on the one hand, and naturalised and birthright citizens, on the other hand, remain unsettled in European case law. Pending cases involving Belgium, Denmark and France should create new opportunities to rule on this issue in the foreseeable future.75 (2) Legislation Regarding Military or Other Services to a Foreign Country (L03 and L04) The first of these two modes of loss of nationality relies on the citizen’s disloyalty due to enrolment in the military or civil service of a foreign state. Nationality is effectively frequently considered as implying a certain degree of fidelity to the state (and, to a lesser extent, to the government) which could be considered incompatible with services rendered to a foreign nation. This mode of loss originates in ancient continental law, and is based on the premise that, in periods of frequent war, serving two kings implies betraying one of them. Twelve Member States have legislation implementing this principle and forbidding their citizens to serve a foreign country, either as in the military or as a civil servant. First, joining the army (L03) is the most frequent operative event, as 11 Member States provide for the loss of nationality in this situation.76 In the vast majority of countries, the loss affects all citizens, irrespective of the way their acquired nationality. Only Cyprus, Estonia and Spain limit nationality loss in this situation to citizens by naturalisation. Serving in the military forces of a foreign state is frequently sufficient, irrespective of the country where this service is carried out. Some Member States, however, limit the range of countries targeted by this provision, such as Cyprus which limits revocation to countries with which it is at war. Cyprus extends this first case to countries with which it has broken 74 K2 v. The United Kingdom, ECLI:CE:ECHR:2017:0207DEC004238713. 75 El Aroud v. Belgium, No. 25491/18; Soughir v. Belgium, No. 27629/18; Ghoumid v. France, No. 52273/16; Charouali v. France, No. 52285/16; Turk v. France, No. 52290/16; Aberbri v. France, No. 52294/16; Ait El Haj v. France, No. 52302/16; Adam Johansen v. Denmark, No. 27801/19. 76 Austria, Cyprus, Estonia, Germany, France, Italy, Latvia, Lithuania, Netherlands, Romania and Spain. 18 Robert Schuman Centre for Advanced Studies Working Papers