The Shifting Parameters of Nationality 283 reason why settler states opted for ius soli.99 Ius sanguinis systems see citizenry rather as a community of descent, which builds on the assumption that kinship guarantees commitment, allegiance and loyalty.100 Whereas ius sanguinis is the system that is most widely used throughout the world,101 increasingly it is complemented by ius soli elements, so as to attempt to include migrants in national community.102 In regard to the naturalisation requirements, the question is always whether the requirements are high enough, so as to make sure that persons acquiring nationality have the requisite attachment and loyalty, without being too high. In the latter regard, political theory about the just society emphasize that long-term residents should have the opportunity to become full members of the polity.103 It has been noted that there is a pendulum back and forth in terms of requirements for migrant naturalisation, a movement to facilitate naturalisation is followed by sharpening requirements again, more particularly because of concerns about failing integration and cohesion.104 The question of dual nationality also comes up here as states can require as precondition for naturalisation that one relinquishes one’s existing nationality.105 4.2 Rights and Obligations Contingent on Nationality This part will mainly discuss the developments that have taken place in terms of rights that are contingent on nationality. While important shifts have taken place in this respect, in that more and more rights have been detached from nationality, the following analysis will demonstrate that the rights that are key to membership in the state are still reserved for nationals. This speaks to the on-going importance of having a nationality and a right to nationality as well as the fight against statelessness. Underscoring the centrality of equality among citizens, and the intrinsic link between citizenship and equal rights, is the case law of international courts that become ever more critical about differentiations in terms of rights between birth right and naturalized citizens.106 It is in any event important to contrast the promise of equal rights that citizenship holds with the reality of often deep-seated discrimination and marginalisation of particular groups of citizens.107 99 Saffran (1997), p. 314. Brubaker (1992), p. 123. 101 For further information see Honohan and Rougier (2018) in this special issue. 102 De Schutter and Ypi (2015), p. 240. However, the increasing integration concerns with third and fourth generation of migrants does lead to more demanding civic integration and related naturalization requirements: Joppke (2007), pp. 39-41. 103 De Schutter and Ypi (2015), p. 238. 104 Joppke (2007), pp. 43-44; Baldi and Goodman (2015), pp. 1154–1155. 105 See Wautelet (2018) in this special issue. 106 Inter alia, European Court of Human Rights (ECtHR) Biao v. Denmark, Application no. 38,590/10, 24 May 2016; ACHPR, Modise v. Botswana, Communications 97/93, 6 November 2000; ACHPR, Open Society Justice initiative v. Cote d’Ivoire, Communications 318/06, 27 May 2016, paras. 99-104. 107 The Roma are a prime example in this respect: Vermeersch (2014), pp. 481–482. 100 123